Approved by

Order of the Federal

Environmental, Industrial

and Nuclear Supervision Service

dated March 19, 2018 No. 113

FEDERAL RULES AND REGULATIONS

IN THE AREA OF ATOMIC ENERGY USE "RULES FOR ARRANGEMENT

AND SAFE OPERATION OF STEAM AND HOT WATER BOILERS

FOR NUCLEAR FACILITIES"

(NP-046-18)

I. General

Purpose and scope

1. These Federal Rules and Regulations in the area of atomic energy use "Rules for arrangement and safe operation of steam and hot water boilers for nuclear facilities" (NP-046-18) (hereinafter referred to as the Rules) are developed in accordance with Federal Law No. 170-FZ dated November, 21, 1995 "On atomic energy use", Provisions for development and approval of federal regulations and rules in the area of atomic energy use approved by Decree of the Government of the Russian Federation No. 1511 dated December 1, 1997 (Collected Acts of the Russian Federation, 1997, N 49, art. 5600; 2012, N 51, art. 7203).

2. These Rules establish the requirements for development, manufacturing, installation, adjustment, repair, refurbishment (retrofitting) and operation of steam and hot water boilers, self-contained superheaters and economizers (hereinafter referred to as boilers) specifically designed for application in the area of atomic energy use and used in operation of nuclear facilities (hereinafter - NF).

3. These Rules shall be applicable to:

1) steam boilers including water heating boilers as well as self-contained superheaters and economizers with the working gauge pressure (hereinafter - the working pressure) of more than 0,07 MPa regardless of hydrostatic pressure;

2) hot water boilers and self-contained economizers with the water temperature exceeding 115 °C;

3) industrial power steam and hot water boilers;

4) waste heat boilers (steam and hot water ones);

5) steam and hot water pipelines within the boiler.

4. These Rules shall not be applicable to:

1) boilers, self-contained superheaters and economizers installed on sea and river vessels and other watercraft (except for dredgers) and underwater facilities;

2) boilers of mobile and transportable plants and power trains;

3) heating boilers of railway carriages and other boilers of mobile boiler plants;

4) electric-heated boilers;

5) boilers with water and steam space volume of 0.001 m³ (1 l) and less and the product of the working pressure (MPa) and volume (m³) not exceeding 0.002 (20);

6) superheaters of tube furnaces at oil refining and petrochemical facilities;

7) soda recovery boilers;

8) boilers operating with high-temperature organic heat transfer media;

9) boilers and their components intended for use at hazardous industrial facilities subject to the requirements of federal regulations and rules in the area of industrial safety "Safety rules for hazardous industrial facilities using pressurized equipment" approved by Order of Rostechnadzor No. 116 dated March 25, 2014 (registered by the Russian Ministry of Justice on May 19, 2014, registration No. 32326, Bulletin of Federal Agency Regulations 2014, N 38).

5. The terms and definitions used in these Rules are given in appendix 1.

Documentation development

6. Development of the engineering documentation for boilers and their components (including spare parts thereof), design documentation for installation, repair and refurbishment of boilers (hereinafter - design and engineering documentation), process control documentation for manufacturing and repair of boilers (hereinafter - the PCD) as well as operation documentation shall be carried out in accordance with these Rules and also with any other regulations and regulatory documents of the operating organization (including standardization documents regulating the requirements for design, arrangement, manufacturing, refurbishment (retrofitting), adjustment, installation, repair, technical diagnostics and operation of boilers) (hereinafter - the RD).

Design and engineering documentation and the PCD for boilers and their components manufactured prior to entry of these Rules into effect or being manufactured as of entry of these Rules into effect shall not be subject to any amendment.

II. Design of boilers

General

7. Design of a boiler and its main parts shall assure safety and reliability of its operation with design parameters within the specified service life of the boiler (component) stated in the boiler certificate as well as the possibility of technical examination, cleaning, flushing, repair and in-service inspection of metal.

Internal devices in the steam and water sections of the boiler drums preventing from examination of the drum surfaces as well as from flaw detection shall be removable.

It is permitted to arrange welded components inside the drum in order to fasten internal devices. The manufacturing organization shall specify the procedure for removal and installation of the above-mentioned devices in the installation and operation manual.

8. Any changes in the design of the boiler and its components necessary in the course of manufacturing, installation, adjustment, repair, refurbishment (retrofitting) and operation of the boiler shall be approved by the developing organization. In the absence of the above-mentioned organization the design changes may be approved by the parent design organization of the nuclear facility or the developer of similar equipment.

9. Design and hydraulic diagram of a boiler, a superheater and an economizer shall provide reliable cooling of walls for the pressurized components.

Temperature of the walls of boiler, superheater and economizer components shall not exceed the value assumed for strength calculations.

10. Configuration of pipes located in gas ducts for removal of the working medium from the economizer shall eliminate the possibility for any steam pocket and clog formation.

11. Design of the boiler shall provide for uniform heating of its components in the course of start-up and under normal operation conditions as well as for the possibility of free thermal expansion for individual boiler components.

Travel indicators (benchmarks) shall be installed at the relevant points in order to monitor movements of boiler components due to thermal expansion. Benchmark installation points shall be specified in the boiler design.

In case it is impossible to provide for free thermal expansion the relevant additional stresses shall be taken into account in strength calculations. In this case installation of benchmarks is not required.

12. A water heater integrated into natural circulation of the boiler (located outside the drum) shall be installed on suspensions (supports) providing for free thermal expansion of the pipes connecting it to the boiler and designed to compensate hydraulic shocks in the boiler.

13. Sections of the boiler components and pipelines with increased surface temperature that can come into direct contact with the operating personnel shall be covered with heat insulation providing the outer surface temperature of not more than 55 °C at the ambient temperature not exceeding 25 °C.

14. Design of the boiler shall provide for air removal from all pressurized components where air plugs can be formed in the course of the boiler filling with water.

15. Devices for feedwater supply, supply of chemicals to the boiler and connection of recirculation pipes as well as feedwater distribution in the drum shall not cause local cooling of the boiler component walls; protective devices shall be provided for this purpose.

16. Arrangement of gas ducts shall eliminate the possibility for any explosion-hazardous gas accumulation and also provide the required conditions to clean gas ducts from depositions of combustion products.

17. The possibility for short-term pressure increase due to "puffs" shall be taken into account in the design of boilers. The possibility for short-term pressure drop after a "puff" shall be taken into account in the boiler design for arrangement of exhausters. Design values of pressure increase and pressure drop shall be selected by the designer.

18. Strength calculations for the pressurized components shall be performed in accordance with the strength calculation standards for stationary boilers and steam and hot water pipelines agreed and approved in accordance with the procedure established by the operating organization.

Water level

19. The lowest permissible water level in gas-tube (shell-type) boilers shall be at least 100 mm higher than the top point of the boiler heating surface.

The lowest permissible water level in the drums of water-tube boilers shall be established by the boiler developing organization.

20. The highest permissible water level in steam boilers shall be established by the boiler developing organization.

Manholes, access doors, covers and fire doors

21. Manholes and apertures (access doors) corresponding to the following requirements shall be provided for drums and headers:

1) manholes in the drums shall be round, elliptical or oval: diameter of a round manhole shall be at least 400 mm and the size of axes for an elliptical or oval manhole shall be at least 300x400 mm;

2) a manhole cover with the weight of more than 30 kg shall be equipped with the device intended to facilitate opening and closing;

3) elliptical or round apertures (access doors) with the minimal diameter of at least 80 mm shall be provided in the headers with the inner diameter of more than 150 mm for the purpose of inspection and internal surface cleaning.

Welded nozzles of circular section plugged with welded end plates to be cut off for inspection (cleaning) may be used instead of above-mentioned access doors. Number and location of the nozzles shall be determined in the course of the boiler designing.

It is permitted not to provide access doors and nozzles in case any pipes with the outer diameter of at least 50 mm are connected to the headers and located in such a way so that access for inspection of the header internals is possible after cutting them off.

22. Manholes and inspection windows shall be arranged in the walls of the furnace and gas ducts in order to monitor the burning process and state of heating surfaces, refractory lining as well as insulation of the heated drum and header sections.

The size of rectangular manholes shall be at least 400x450 mm, the diameter of round ones shall be at least 450 mm; they shall provide the possibility to get into the boiler for surface inspection of its components (except for heat- and gas-tube boilers).

Fire doors and ports of burner units may be used as manholes provided that their size is at least equal to the values specified in this paragraph.

23. Doors and covers of manholes, access holes and inspection windows shall be strong and tight-fitting and shall prevent any possibility for self-opening.

Access doors in the gas ducts of boilers with excessive gas pressure in the furnace shall be equipped with devices to prevent furnace puffs in case of opening.

Safety devices of furnaces and gas ducts

24. Boilers with in-chamber combustion of fuel (powdery, gaseous or liquid) or with a shaft-type furnace for combustion of peat, saw dust, chips or any other fine production wastes with the steam capacity of up to 60 t/h (inclusive) shall be equipped with rupture protection devices. Rupture protection devices shall be located and arranged in such a way so that to prevent any damage to people.

Boilers with in-chamber combustion of any fuel and the steam capacity exceeding 60 t/h shall not be equipped with rupture protection devices. Reliable operation of these boilers shall be assured by the automatic system of protections and interlocks in all operation modes.

25. Design, number, location and flow area of the rupture protection devices shall be defined in accordance with the boiler design.

26. A tripping device shall be installed between the waste heat boiler and the process unit in order to ensure the unit operation without the waste heat boiler.

It is permitted not to install the tripping device provided that the process unit operation mode enables to shut the boiler down and fulfill the requirements of these Rules for technical examination or repair of boilers.

Cast-iron economizers

27. Connection schemes for cast-iron economizers shall comply with the requirements of the installation and operation manual.

28. Water temperature at the cast-iron economizer outlet shall be at least 20 °C below the saturated steam temperature in a steam boiler drum or the vaporization temperature at the existing working water pressure in a hot water boiler.

End plates and tube sheets

29. Boiler end plates shall be dished, hemispherical or elliptical.

Usage of torospherical end plates with raised edge or flat end plates with or without raised edge is permitted for heat- and gas-tube boilers. Flat end plates shall be fixed with longitudinal and (or) angle braces.

Usage of flat end plates with the inner diameter not exceeding 600 mm is permitted for headers of water-tube boilers. Usage of flat end plates with the inner diameter exceeding 600 mm is permitted for headers of water-tube boilers provided that the header operation life is substantiated by the checking strength calculation and recommendations of the boiler developing organization for the in-service inspection of these end plates are available.

30. End plates shall be made of one sheet. It is permitted to make end plates of two sheets provided that the sheets have been welded prior to pressing and the weld joint has been subjected to radiographic control or ultrasonic control (hereinafter - USC) along the entire length subsequent to the end plate manufacturing.

31. It is permitted to make tube sheets of two and more sheets provided that the distance between the adjacent weld joints is at least equal to fivefold wall thickness and weld joints are subjected to USC or radiographic control along their entire length.

32. Flat end plates with grooves on their inner surface or with a cylindrical section made by mechanical boring shall be manufactured from a forged piece checked for uniformity by USC.

It is permitted to use flat steel at the working pressure of up to 4 MPa and the medium temperature of up to 450 °C subject to complete USC of the blank or the manufactured end plate or complete inspection through the use of any other method approved by the operating organization.

33. Elliptical, torospherical and flat edge-raised end plates shall have cylindrical edges.

34. Flat and dished end plates with the outer diameter of not more than 80 mm may be manufactured from a round rolled billet by mechanical processing.

Weld joints

35. Weld joints shall be butt ones with full penetration.

Use of corner welds is permitted subject to complete USC or radiographic control. It is permitted to use corner welds with a structural gap without any USC or radiographic control in order to weld pipes and nozzles with the inner diameter not exceeding 100 mm as well as flat flanges (regardless of their diameter) and aperture reinforcement elements to headers and drums of water-tube boilers and shells of gas-tube boilers.

Quality control for the above-mentioned weld joints shall be arranged in accordance with these Rules and the design and engineering documentation.

It is permitted to use overlap joints for welding of the external pipe couplings with the nominal size of less than 16 mm as well as for welding of cover plates and casings.

36. Smooth transition from one part to another by gradual thinning of the more thick-walled part with inclination angle of each transition surface not exceeding 15° shall be arranged for butt weld joints between parts with different nominal thickness.

Inclination angle of the transition surfaces may be increased to 30° provided that reliability of the joint is substantiated by strength calculations with determination of the specified operation life.

In case the difference in the nominal wall thickness of the welded elements is below 30% of the wall thickness of the thinner element but does not exceed 5 mm it is permitted to arrange the above-mentioned smooth transition at the beveling side due to inclination of the seam surface.

The requirements for butt joints between the elements with different thickness and different strength properties shall be defined in accordance with the PCD.

37. Design and location of weld joints shall provide:

1) the possibility to arrange weld joints in compliance with all requirements specified in the PCD;

2) free placement of heating devices in case of any local thermal treatment;

3) the possibility to perform quality control for weld joints using the prescribed methods;

4) the possibility for repair of weld joints with subsequent thermal treatment and control in case these are prescribed in the PCD.

38. Intersection of butt weld joints is not allowed. Displacement of weld joint axes coming to the weld joint boundary in parallel or angle-wise shall be at least equal to threefold thickness of the thickest sheet and not less than 100 mm.

Above-mentioned requirements are not mandatory for butt weld joints between the parts with the nominal wall thickness of up to 30 mm inclusive as well as for prefabricated assembly units made of parts with different nominal thickness subject to simultaneous fulfillment of the following conditions:

1) weld joints shall be made by automatic welding;

2) intersection points of weld joints shall be subject to USC and radiographic control.

39. In case any apertures are located near weld joints the distance between the intersection point of the weld joint axes and the nearest aperture edge shall be at least  where D_m and S are the mean diameter and the thickness of the element with apertures (mm).

Measurements shall be performed on the inner surface for the drums and on the outer surface for other components.

40. The minimal distance between the seam exes of any adjacent non-coupled butt weld joints (particularly cross-sectional, longitudinal, meridional, chordal and circular) shall be at least equal to the nominal thickness of welded parts but not less than 100 mm for the wall thickness exceeding 8 mm and not less than 50 mm for the wall thickness of 8 mm and less.

41. Length of the cylindrical edge from the butt weld joint axis to the beginning of the dished end plate curve or any other edge-raised component shall provide for the possibility of USC for the end plate welding joint from the end plate side.

42. Weld joints of boilers shall not come in contact with supports. If supports are located above (under) weld joints the distance from the support to the weld seam shall be sufficient to perform the required weld joint monitoring in the course of operation.

Supports may overlap cross-sectional weld joints of cylindrical shells of boilers operated in horizontal position provided that the overlapped sections of weld joints with the allowance of at least  but not less that 100 mm per side have been subjected to complete radiographic control or USC.

Weld joint intersection and adjoining points shall not be overlapped with supports.

43. The distance from the butt weld joint seam edge to the axis of apertures for pipe expanding or welding shall be at least equal to 0,9 of the aperture diameter. Apertures for welding of pipes or nozzles may be located on butt weld joints and at the distance of less than 0,9 of the aperture diameter from them provided that the following conditions are fulfilled:

1) prior to boring weld joints shall be subject to radiographic control or USC at the aperture section with the allowance of at least  and not less than 100 mm per each side of the weld seam;

2) the specified operation life shall be substantiated by the checking strength calculations.

It is permitted not to perform calculations if the distance between the edges of apertures located in a longitudinal joint is not less than  and for apertures in a circular (cross-sectional) joint - not less than .

Apertures for pipe expanding may be located in butt weld joints in accordance with the PCD requirements.

44. The distance between the centers of two adjacent apertures in shells and dished end plates on the outer surface shall be at least equal to 1.4 of the aperture diameter or 1.4 of the semi-sum of aperture diameters in case the diameters are different.

The above-mentioned distance may be reduced to 1,3 of the diameter if the apertures are located in a single transverse or longitudinal row. The distance between the apertures in such a row may be reduced to 1,2 of the aperture diameter in case the pipes of a gas-tight membrane panel are installed in it with welding on the pipe header surface and spacers (or fins) between them along the entire length of the panel attached to the header.

Curved elements

45. Design of elbows and curved headers shall comply with the regulatory documentation.

46. Pressed and welded elbows may be used with one cross-sectional weld joint or one or two longitudinal weld joints of diametrical arrangement provided that radiographic control or USC is performed along the entire length of weld seams.

47. Wall thickness at the external and internal side as well as out-of-roundness of the elbow cross-section shall not exceed the permissible values specified in the design and engineering documentation.

48. It is not permitted to use elbows curved due to creases (corrugation) inside the elbow.

49. Usage of sector elbows is permitted under the working pressure not exceeding 4 MPa provided that the angle between cross-sections of sectors does not exceed  22°30'  and the distance between adjacent weld joints on the inner surface of the elbow ensures control of these joints from both sides on the outer surface.

Expanded joints

50. Expanded joints arranged through the use of manual or mechanical expansion as well as by blasting inside the expanded pipe shall be used for pipes with the outer diameter not exceeding 108 mm and with the pipe wall temperature at the expansion point not exceeding 400 °C under operation conditions.

Subject to the above-mentioned limitations it is permitted to use expanded joints with pipe seal welding prior or after expanding.

51. Nominal wall thickness for the shell or tube sheet in case of expanded joints shall be at least 13 mm.

52. Design of the expanded joint (with one or several grooves made by boring or knurling and also without any grooves with or without the "bell" flaring) shall comply with the design and engineering documentation.

53. The permissible out-of-roundness for the aperture, height of the protruding pipe part or depth value, the angle of "bell" flaring shall comply with the design and engineering documentation.

54. No cracks and ruptures on the "bell" edge are permitted.

Blowdown, emptying and drainage systems

55. Each boiler shall have the following pipelines:

1) feedwater or delivery water supply;

2) boiler blowdown and water drainage in case of the boiler shutdown;

3) air removal from the boiler in the course of filling with water and start-up;

4) superheater and steam line blowdown;

5) water and steam sampling;

6) injection of any corrective reagents to boiler feedwater in the course of operation and detergents for chemical cleanup of the boiler;

7) water and steam removal in the course of start-up and shutdown;

8) drum heating in the course of start-up.

The possibility to combine the above-mentioned pipelines or their absence shall be specified in the design and engineering documentation.

56. Number of blowdown, discharge, drainage and air pipelines and points of their connections to the boiler components shall be selected by the boiler developing organization so that to provide removal of water, condensate and residue from the lowest sections of the boiler and air removal from the top ones. In case removal of the working medium cannot be arranged by gravity forced removal shall be provided.

57. The blowdown pipeline shall discharge water to a non-pressurized tank. A pressurized tank may be used subject to confirmation of blowdown efficiency and reliability with the relevant calculations.

58. Drains providing condensate removal shall be arranged at all steam pipeline sections that may be isolated with shut-off valves.

59. Design and layout solutions of the blowdown, emptying, drainage and reagent injection systems adopted by the developing and designing organizations for particular equipment shall provide reliable operation of the boiler in all modes (including emergencies) as well as its reliable preservation in case of any down time.

Burner units

60. Burner units shall assure safe operation of boilers.

61. Burner units shall be manufactured in accordance with the process control documentation. Safety requirements shall be established and instructions for operation and repair of burner units shall be presented in the regulatory documents of the operating organization.

62. Newly manufactured and imported burner units shall be authorized for operation on the basis of conformity assessment performed for the burner units and testing of the operational availability of burner units.

63. Burner units shall have certificates of the manufacturing organization with indication of the basic information (including name and address of the manufacturer, serial number, date of manufacture, engineering solutions, basic dimensions, working media parameters, type, capacity, adjustment range and the main technical characteristics). The certificate format shall be established by the manufacturer. All burner units are subject to acceptance, qualification and type tests.

64. The boiler shall be equipped with:

1) a set of main and backup atomizers; number of backup atomizers and atomizers for burners of coal-dust boilers using liquid fuel for start-up shall be defined in the design and engineering documentation;

2) ignition safety devices controlling the ignition and the main flame; places for installation of ignition safety devices and flame control means shall be defined in the design and engineering documentation;

3) a set of valves providing automatic remote or manual control of burner units.

65. Burner units developed and supplied together with the boiler by the same manufacturing organization shall pass acceptance testing within this boiler (in the boiler prototypes concurrently with general testing of the boiler).

66. Burner units shall provide reliable ignition and stable burning of fuel without any flame lift-off and flashbacks within the prescribed range of operation modes, prevent from liquid fuel drop deposition on the furnace floor and walls as well as coal dust separation (in case no special-purpose measures for its afterburning in the furnace volume are taken).

67. Aerodynamic characteristics of the burners and their location on the furnace walls shall provide uniform flame distribution in the furnace without any impingements and eliminate any dead and poorly ventilated zones within the furnace volume.

69. Residual fuel oil or natural gas shall be used as start-up fuel for start-up devices of coal-dust burners.

Usage of other liquid fuel types with the flash point of at least 61°C is permitted.

It is not permitted to use highly flammable fuel types as start-up fuel.

69. The fuel oil atomizer shall be located in the burner in such a way so that to prevent contact of the fuel oil atomizer spray unit (head) with high-temperature combustion products.

70. Fuel supply to the burners, the requirements for shutoff and control valves and isolating (safety) valves, the list of necessary protections and interlocks as well as the requirements for fuel preparation and supply shall be defined for each fuel type in accordance with the requirements of design and engineering documentation and fire safety regulations.

71. Uniform distribution of loads on the boiler suspensions and state of the suspension system elements shall be controlled in the course of the boiler operation. Tension of the suspensions after installation and in the course of operation shall be adjusted in accordance with the manuals of the boiler manufacturing organization.

III. Materials and semi-finished products

General

72. Any materials and semi-finished products used in manufacturing of boilers shall assure safe operational parameters determined by their mechanical properties, chemical composition, manufacturing technology, testing and quality control methods and scope, the warranted level of design and process characteristics and shall comply with the requirements of the design and engineering documentation and regulatory documents for the materials.

73. It is permitted to use other materials provided that quality and properties of the materials shall be at least equal to the requirements of the design and engineering documentation and subject to presence of the relevant substantiated technical solution for material replacement approved by the boiler manufacturing organization and the opinion of the main material research organization. A copy of the above-mentioned solution (opinion) shall be attached to the boiler certificate.

74. Supply of semi-finished products for manufacturing, installation, repair and refurbishment (retrofitting) of boilers shall be arranged in accordance with the design and engineering documentation and documentation of the boiler manufacturing organization.

75. Incoming control of the main and welding materials and semi-finished products in accordance with the PCD shall be performed prior to manufacturing, installation, adjustment, repair and refurbishment (retrofitting) of a boiler.

76. Impact of low temperatures in the course of the boiler storage, installation, adjustment, repair, refurbishment (retrofitting) and operation shall be taken into account apart from the operating parameters in selection of the materials for boilers supplied to any cold regions.

Administrative and technical measures and the method for consideration of low temperature impacts shall be specified in the boiler installation and operation manual.

77. Each semi-finished product used for the boiler manufacturing, installation, adjustment, repair or refurbishment (retrofitting) shall have the labeling containing the manufacturing organization designation, steel grade and its manufacturing standard or technical specifications (hereinafter - TS).

The labeling method shall be established by the manufacturer's documentation for the semi-finished product; in this case any unacceptable modification of the semi-finished product metal properties shall be prevented and integrity of the labeling within the entire period of its operation shall be assured where practicable.

78. Labelling of pipes with the diameter of 25 mm and more and wall thickness of 3 mm and more shall include the trademark of the manufacturing organization, steel grade and batch number. It is permitted to label pipes with the diameter of less than 25 mm and any thickness and the diameter of more than 25 mm and thickness of less than 3 mm through the use of tags tied to tube bundles; the following information shall be specified in the labelling: trademark of the manufacturing organization, pipe size, steel grade, batch number, number of the regulatory documentation for manufacturing.

Steel semi-finished products

General requirements

79. The manufacturing organization of semi-finished products shall control chemical composition of the material. Accompanying documents for the semi-finished product shall contain the results of chemical analysis obtained directly for the semi-finished product or the blank (except for castings) used for its manufacturing.

80. Semi-finished products shall be supplied after heat-treatment. Heat treatment regime shall be specified in the accompanying documentation of the semi-finished product manufacturing organization.

It is permitted to supply semi-finished products without heat treatment in the following cases:

1) mechanical and processing characteristics of metal specified in the RD for metal are assured by the semi-finished product manufacturing technology;

2) the semi-finished product is subjected to hot forming with concurrent or subsequent heat treatment in the course of the boiler manufacturing, repair or refurbishment (retrofitting).

In the above-mentioned cases the supplier shall control the properties of semi-finished products through the use of heat-treated samples.

In any other cases acceptability of semi-finished products without heat treatment shall be confirmed by the opinion of the main material research organization.

81. The manufacturing organization of semi-finished products shall control mechanical properties of metal by tensile strength testing at 20 °C with determination of breaking stress and 0.2 or 1% proof stress or yield point, relative elongation and relative reduction of area (in case cylindrical samples are tested). If only relative area reduction values are regulated control of relative elongation is not mandatory.

82. In accordance with the requirements of these Rules semi-finished products with the sheet, forging (casting) or pipe wall thickness of 12 mm and more and the round bar (forged piece) diameter of 16 mm and more shall be subject to impact testing.

83. Metal of the parts for flanged connections of pipelines laid under the open sky, in the ground, in channels or in unheated rooms where metal temperature can be below 0°C as well as other parts specified in the design and engineering documentation shall be subject to impact testing at the temperature of  0°C.

84. Impact tests for the samples with U-type concentrator shall be performed at -20 °C and in any cases stipulated in par. 83 of these Rules - at one of the temperature values specified in Table No. 1 of these Rules.

Table No. 1

Impact tests for samples with V-type concentrator shall be performed in accordance with the RD for semi-finished products at 20 °C and -20 °C.

Impact viscosity at the above-mentioned test temperatures shall be at least  KCU = 30 J/cm²; KCV = 25 J/cm². The arithmetic mean for three testing results with the bottom value deviation from the standard for an individual sample not exceeding 10 J/cm² but at least equal to the above-mentioned values shall be defined to assess impact viscosity.

KCU or KCV impact viscosity criterion shall be selected by the boiler developing organization and specified in the design and engineering documentation.

85. Material of sheet and rolled products for  attach hardware made of carbon, low-alloyed manganese and silico-manganese steels subject to cold forming without subsequent tempering in the course of manufacturing and intended for operation at the temperature of 200 - 350 °C shall be subjected to impact testing after mechanical ageing. Standard values of impact viscosity after mechanical ageing shall comply with the requirements of par. 84 of these Rules.

86. Standard values of yield point at elevated temperatures shall be specified in the regulatory documentation for semi-finished products intended for the parts operated under the design temperature exceeding 150 °C: for carbon and low-alloyed manganese and silico-manganese steels - up to 400 °C, for chromium-molybdenum and chromium-molybdenum-vanadium steels - up to 450 °C and for high-chromium and austenitic steels - up to 525 °C. Maintenance of yield point values at the level required by the RD shall be assured by adherence to the production technology and regular control of the products. Surveillance tensile strength tests at elevated temperatures prescribed by the RD and also performed in the course of new material assimilation shall be carried out at one of the temperature values within the above-mentioned range divisible by 10 °C or 25 °C. In this case 0,2 or 1% proof stress shall be standardized as an acceptance characteristic and breaking point, relative area reduction or elongation shall be determined as reference data.

87. Material of semi-finished products intended for operation at the design temperature exceeding the values specified in par. 86 of these Rules shall have creep-rupture strength at least equal to the RD requirements for the material.

Warranted creep-rupture strength limits with the operation life of 10⁴, 10⁵ and 2·10⁵ h shall be substantiated by statistical processing of the test data, regular control of products and confirmed by the positive opinion of the main material research organization.

88. The list of mechanical characteristics control types may be reduced in comparison with the RD for the material subject to the relevant warranties provided by the semi-finished product manufacturing organization. Warranties shall be assured by application of statistical processing methods for the data of the manufacturing organization certificates, testing results (including tensile strength tests) and regular control of the products. Application of these methods shall be prescribed in the design and engineering documentation. Warranties shall be confirmed by the positive opinion of the main material research organization.

Sheet steel

89. Conditions for use of sheet steel and steel strips of various grades and types of mandatory testing and control shall comply with the RD for sheet steel.

Steel pipes

90. Conditions for use of pipes made of various steel grades and types of mandatory testing and control shall comply with the RD for pipes.

91. Seamless pipes shall be manufactured of rolled, forged, continuously cast and centrifugal-cast blanks.

92. Usage of electric-welded pipes with longitudinal or spiral joints is permitted subject to radiographic control or USC of the weld seam along the entire length.

93. Each seamless or welded pipe shall be subject to hydraulic testing under the test pressure indicated in the RD for pipes.

It is permitted not to carry out hydraulic testing of seamless pipes in the following cases:

1) the pipe is subjected to radiographic control or USC across the entire surface;

2) for pipes with the working pressure of 5 MPa and less if the pipe manufacturing organization guarantees positive results of hydraulic testing.

94. Usage of expanded pipes made of any material not checked for impact viscosity after mechanical ageing without subsequent heat treatment for the temperatures exceeding 150 °C is permitted for straight sections provided that plastic deformation in the course of expanding does not exceed 3%.

95. Welded pipes for parameters and conditions not specified in the RD for pipes shall be permitted for use based on the positive opinion of the main material research organization subsequent to the results of studies confirming their strength and reliability.

Steel forged, pressed and rolled pieces

96. Conditions for use of forged, pressed and rolled pieces made of various steel grades and types of mandatory testing and control shall comply with the RD for forged pieces.

97. Round bars with the outer diameter of up to 80 mm may be used for manufacturing of parts by cold mechanical processing. Round bars with the outer diameter not exceeding 160 mm may be used for hollow-bored round parts with the wall thickness of not more than 40 mm and the length up to 200 mm. Rolled products are subject to radiographic control or USC within the entire volume in the rolled product manufacturing organization or in the boiler manufacturing organization.

Non-destructive control of finished parts or after preliminary mechanical processing is permitted.

98. Conditions for use, types of mandatory testing and control for forged, pressed and rolled pieces shall comply with the requirements of the RD for forged pieces.

Cast steel

99. Conditions for use of cast pieces made of various steel grades and types of mandatory testing and control shall comply with the RD for cast pieces.

100. The minimal wall thickness of cast pieces after mechanical processing shall be at least equal to the design thickness but at least 6 mm.

101. Cast pieces made of carbon steels with the carbon content not exceeding 0.28% may be welded without any preheating.

102. Each hollow-bored cast piece shall be subject to hydraulic testing under the test pressure specified in the RD for cast pieces.

Hydraulic testing of cast pieces subjected to complete radiographic control or USC in the manufacturing organization may be combined with hydraulic testing of the boiler components under the test pressure specified in the RD.

Attach hardware

103. Conditions for use of various steel grades for attach hardware and types of mandatory testing and control shall comply with the RD for attach hardware.

104. Materials of fasteners shall be selected with the linear expansion coefficient close to the similar coefficient of the material for flanges; in this case the difference between the linear expansion coefficients shall not exceed 10%. Steels with different linear expansion coefficients (more than 10%) may be used in cases justified by strength calculations or experimental studies and also in cases when the design temperature of attach hardware does not exceed 50 °C.

105. In case fasteners are manufactured by cold forming they shall be subject to heat treatment - tempering (except for the parts made of carbon steel and operated at the temperature up to 200 °C).

If threading is arranged by knurling no further heat treatment of the fasteners is required.

106. Nuts and pins (bolts) shall be made of different steel grades; in case they are made of the same steel grade steel hardness shall be different. In this case the nut hardness shall be less than the pin (bolt) hardness. Length of pins (bolts) shall exceed the threaded section above the nut by at least 2-3 turns and comply with the requirements of the RD for attach hardware.

Iron castings

107. Conditions for use of cast pieces made of various cast-iron grades and types of mandatory testing and control shall comply with the RD for iron castings.

108. Wall thickness of iron castings after mechanical processing shall be not less than 4 mm and not more than 50 mm.

109. Cast pieces made of high-strength cast iron shall be used after heat treatment.

110. Each hollow-bored cast piece shall be subject to hydraulic testing under the test pressure specified in the RD for cast pieces but at least 0,3 MPa.

111. It is not permitted to use iron castings for boiler components and valves subjected to dynamic loads and thermal shocks.

112. Cast pieces made of annealed or high-strength cast iron shall be used for manufacturing of shut-off elements, blowdown, discharge and drainage lines.

Non-ferrous metals and alloys

113. Bronze and brass may be used to manufacture parts of valves and instrumentation operated at the temperature not exceeding 250 °C.

114. Hydraulic testing of valve casings shall be performed in accordance with the RD for pipeline valves.

New steel grades

115. Usage of materials and semi-finished products made of new steel grades shall be permitted subject to the relevant substantiated technical solution for material replacement approved by the boiler developing and (or) manufacturing organization and in case of their absence - based on the opinion of the main material research organization developed with due regard for the data on the basic mechanical, physical and processing properties of the materials after basic and additional heat treatment.

A copy of the above-mentioned solution (opinion) shall be attached to the boiler certificate.

116. Mechanical properties (breaking point, 1% proof stress for austenitic and chromium-nickel steels and 0.2% proof stress for other steel grades) shall be investigated within the range from 20 °C to the temperature exceeding the maximum recommended value by at least 50 °C.

Testing temperature shall be selected in order to obtain clear dependency between changes of steel strength properties and temperature. Temperature intervals shall not exceed 50°C.

For sheets and pipes the ration between standard values of yield point and breaking point at the temperature of 20 °C shall not exceed 0.6 for carbon steel and 0.7 for alloyed steel. For attach hardware the above-mentioned ratio shall not exceed 0.8.

117. Experience-based data shall be presented for the materials intended for operation under high temperatures causing creep in order to determine the creep-rupture strength values for 10⁴, 10⁵ and 2 · 10⁵ h and conventional creep limit.

The number of performed short-term and long-term tests and their duration shall be sufficient to define steel strength characteristics and to assess scattering of the above-mentioned characteristics with due regard for the semi-finished product size (wall thickness) and any deviations of mechanical properties (with minimal and maximal values) and chemical composition (metal from the casts with the least favorable content of alloying elements in relation to high-temperature strength shall be studied) as specified in the TS.

118. In case steel is prone to structural changes in the course of operation data characterizing these changes and their impact on the steel performance shall be presented.

119. Susceptibility of steel to work hardening shall be assessed on the basis of any changes in its creep-rupture strength and stress-rupture ductility by comparative testing of work-hardened and mild materials.

Material of semi-finished products subject to cold deformation in the course of processing shall be checked for absence of any susceptibility to mechanical ageing.

120. The possibility for steel usage shall be confirmed by the data on its resistance to brittle failures obtained through impact testing or by any other method selected in accordance with the material operation conditions within the product.

121. Welding characteristics of steel shall be confirmed by testing of weld joints performed in accordance with the recommended technique with application of the relevant welding fillers. Testing results for the weld joints shall confirm their operability and define the effect of welding techniques and heat treatment regime on the weld joint properties.

Data on creep-rupture strength of weld joints and resistance to local failures in the weld-affected zone during long-term operation shall be presented for heat-resistant materials.

122. When developing new materials it is necessary to take into consideration their operation conditions causing the need to broaden the requirements for assessment of the relevant properties of steel and weld joints:

1) for operation under sub-zero temperatures - cold resistance assessment;

2) in case of cyclic loads - cyclic strength assessment;

3) under active impact of media - assessment of corrosion resistance and mechanical strength.

123. The following data on physical properties shall be presented for any new steel grade:

1) modulus of elasticity at various temperatures;

2) linear expansion coefficient within the relevant temperature range;

3) thermal conductivity coefficient at the relevant temperatures.

124. The possibility to make semi-finished products of the recommended steel grade shall be justified by the semi-finished product manufacturing organization or the main material research organization.

IV. Manufacturing, installation, adjustment, repair and refurbishment

(retrofitting) of boilers

General

125. Manufacturing, installation, adjustment, repair and refurbishment (retrofitting) of boilers shall be carried out by organizations having any equipment and trained personnel required to perform the works properly.

126. Manufacturing, installation, adjustment, repair and refurbishment (retrofitting) of boilers shall be performed in accordance with the requirements of the design and engineering documentation and these Rules.

127. Manufacturing, installation, adjustment, repair and refurbishment (retrofitting) of boilers and their separate components shall be performed in accordance with the procedure developed by the organization performing the works prior to their commencement.

128. The quality control system (incoming, in-process and acceptance control) assuring performance of the works in accordance with the requirements of these Rules, design and engineering documentation shall be applied in the course of manufacturing, installation, adjustment, repair and refurbishment (retrofitting) of boilers.

Cutting and forming of semi-finished products

129. Cutting of sheets, pipes and other semi-finished products as well as cutting of apertures may be performed through the use of any method (mechanical, gas-flame, arc, plasma-based). The thermal cutting technique for materials sensitive to local heating and cooling shall prevent from formation of any edge cracks and deterioration of properties in the heat-affected zone and also shall provide for preheating and subsequent mechanical processing of edges in any cases prescribed by the PCD in order to remove the metal layer with the properties deteriorated in the course of cutting.

The particular cutting method and technique shall be defined in the process control documentation depending on steel classes (material characteristics).

130. Expanding and pressing of shells and end plates as well as upsetting of collars and processing of flat end plates shall be carried out by machining. End plates may be manufactured by machine forging with subsequent mechanical processing. Flattening of sheets with a hammer with local heating or without any heating is not allowed.

131. Pipes may be bent through the use of any method (with or without pipe heating) which ensures bending in compliance with the PCD requirements.

132. Boring, flaring or crimping of the pipe ends is permitted to provide proper match of the pipe cross-sectional joints. Acceptable boring value, flaring or crimping deformation shall be taken in accordance with the regulatory documents.

133. Labelling of the manufacturing organization shall be preserved on sheets, rolled products and forged pieces intended for manufacture of the pressurized parts as well as on the pipes with the outer diameter exceeding 76 mm.

If the above-mentioned semi-finished products are to be cut into pieces labelling shall be relocated on the separate parts.

134. When manufacturing welded dished end plates pressing shall be carried out subsequent to welding of sheets and mechanical flush finishing. The above-mentioned requirement shall not be applicable to spherical end plates welded of pressed elements.

Welding

135. Operable plants, equipment and devices ensuring compliance with the requirements of the design and engineering documentation shall be used for welding.

136. Welding operators with licenses issued in accordance with the procedure established by the operating organization shall be admitted to perform welding works.

Welding operators may be admitted only to the types of welding works specified in their licenses.

137. Any welding operator in the organization who commences welding of pressurized items for the first time regardless of the license availability shall pass verification by welding and control of a test weld joint prior to work authorization. Design of test weld joints as well as quality control methods and scope for these weld joints shall be established by the welding work supervisor.

138. Supervision over the works for assembly and welding of boilers and weld joint quality control shall be assigned to specialists checked for knowledge of these Rules.

139. All weld joints of pressurized components shall be subject to labelling (stamping) enabling to define the surname of the welding operator who has performed welding. In case any weld joint is performed by several welding operators stamps of all welding operators engaged in arrangement of this weld joint shall be applied.

The labelling system shall be specified in the process control documentation. The labelling technique shall eliminate work hardening, additional heating or unacceptable metal thinning and ensure integrity of the labelling within the entire service life of the item. The stamp shall be applied at the distance of 20-50 mm from the weld joint edge on the exterior side. In case the joint is welded by different welding operators from the exterior and interior side stamps shall be applied only on the exterior side with a slash: in the numerator - the stamp of the welding operator who has performed the weld joint from the exterior side and in the denominator - the stamp of the welding operator who has performed the weld joint from the interior side.

For longitudinal joints the stamp shall be applied in the beginning and in the end of the weld seam at the distance of 95-105 mm from the circular joint. Only one stamp may be applied to a shell with a longitudinal joint shorter than 400 mm. For a circular joint the stamps shall be placed at the point of intersection between the circular and the longitudinal joint and every 2 m further; in this case at least two stamps shall be applied to each joint. Longitudinal and circular joints with the wall thickness of less than 4 mm may be stamped through the use of an electric etcher or indelible paint (except for the boiler components made of austenitic steels where data may be inscribed by mechanical engraving).

The stamping area shall be enclosed in a clearly visible box and specified on the drawing in the boiler certificate.

140. Welding materials used for welding of boilers shall comply with the requirements of the design and engineering documentation.

141. Grades, assortment, storage conditions and preparation of the welding materials for use shall comply with the PCD requirements.

142. In addition to inspection of the welding materials according to par. 75 of these Rules the following shall be checked:

1) each pair of electrodes:

for welding and processing properties;

for compliance of the alloying element content in the weld metal arranged with the use of alloyed electrodes (E-09H1М, E-09H1МF types, austenitic) with the standard composition through chemical composition control by positive material identification test or any other spectrum analysis method used for chemical composition control;

2) each batch of flux cored wire - for welding and processing properties;

3) each bunch (bundle, coil) of alloyed welding wire - for presence of the main alloying elements by positive material identification test or any other spectrum analysis method confirming presence of alloying elements in metal.

143. Preparation of edges and surfaces for welding shall be performed by mechanical processing or by thermal cutting or gouging (oxygen, air arc or plasma arc) with subsequent mechanical processing. Depth of mechanical processing after thermal cutting (gouging) shall be specified in the process control documentation depending on the particular steel grade susceptibility to the thermal cycle of cutting (gouging).

144. In the assembly of butt joints of pipes without backing rings with single-side edge preparation and pipes welded without any root backing displacement (misalignment) of the inside edges shall not exceed the values specified in the process control documentation.

145. Edges of parts to be welded and adjacent areas shall be cleaned from any slag, paint, oil and other contaminants in accordance with the PCD requirements.

146. Welding and removal of auxiliary elements (assembly devices, temporary bracing) shall be performed in accordance with the drawings and the PCD through the use of the technique preventing formation of cracks and tempered zones in the metal of pressurized equipment.

147. Tack weld of the components assembled for welding shall be arranged with the use of the same welding materials as used or permitted for use in welding of this joint.

148. Techniques shall be permitted for use in manufacturing, installation, adjustment, repair and refurbishment (retrofitting) of boilers after confirmation of their performance on physical items, verification of the entire set of the required properties of weld joints and assimilation of efficient quality control methods.

149. It is not permitted to use gas welding for any parts made of austenitic and high-chromium steels of martensitic and martensitic-ferritic classes.

150. Pressurized components shall be welded at positive temperature of the ambient air. It is permitted to perform welding works at sub-zero temperatures subject to compliance with the PCD requirements and arrangement of the required conditions for protection of the welding site and the welding operator against wind and precipitation.

In case of negative temperatures of the ambient air metal in the weld joint area shall be dried and heated prior to welding in order to achieve positive temperature values.

151. Necessity and regime of preliminary and concurrent heating of the welded parts shall be defined by the welding technique and specified in the process control documentation. In case of sub-zero temperature of the ambient air heating shall be arranged in the same cases as for positive one but the heating temperature shall be higher by 50°C.

152. Subsequent to welding the joint and adjacent areas shall be cleaned from any slag, metal splash and other contaminants.

Inner burr on the pipe joints arranged by electrical resistance welding shall be removed in order to ensure the prescribed flow area.

Heat treatment

153. Heat treatment of boiler components shall be performed in order to assure compliance of metal and weld joint properties with the parameters specified in the design and engineering documentation and also to reduce residual stresses caused by processing operations (including welding, bending and pressing).

Semi-finished products, assembly units and whole items shall be subject to heat treatment as prescribed in the process control documentation with due regard for recommendations of the boiler manufacturing organization specified in the boiler operation manual.

154. There may be two types of heat treatment:

1) basic one including annealing, annealing with tempering, hardening, temper hardening, austenite conditioning and multi-stage heat treatment with heating up to hardening or austenitization temperatures;

2) additional one in the form of tempering.

Types of the basic and additional heat treatment and its regimes (particularly heating rate, holding temperature and time, cooling rate and the cooling medium type) shall be adopted in accordance with the PCD and these Rules.

Heat treatment operators having passed theoretical and practical training and possessing licenses for performance of the relevant works shall be admitted to carry out heat treatment works.

155. Items are subject to basic heat treatment in the following cases:

1) if semi-finished products (sheets, pipes, cast and forged pieces) have not been subjected to heat treatment according to the regimes ensuring the material properties and specified in the RD for metal;

2) if any forming operations (bending, expansing, pressing) have been performed with heating up to the temperature above the tempering temperature;

3) after slag welding;

4) after bending of pipes made of austenitic steel (regardless of the pipe outer diameter and the bending radius);

5) when basic heat treatment is prescribed in the manufacturing and welding documentation.

156. Basic heat treatment is not mandatory when forming operations (bending, expansing, pressing) have been performed:

1) for parts and semi-finished products made of carbon and manganese and silico-manganese steels with heating up to the annealing temperature not less than 700 °C in the end;

2) for pipes made of austenitic steels in the course of bending on the machines with high-frequency heating up to austenitization temperature with spray cooling;

3) for parts and semi-finished products made of austenitic chromium-nickel steels at the temperature of at least 850°C.

157. Items are subject to additional heat treatment (tempering) in the following cases:

1) after expanding and pressing of parts made of carbon, manganese and silico-manganese steels without any heating or with heating below 700 °C if the wall thickness is more than 36 mm (regardless of the bending radius) and also in case the wall thickness exceeds 5% of the inner diameter of the shell, the minimal inner curvature radius of end plates, the inner radius of a nozzle (branch) for pressed tee fittings or the mean curvature radius of elbows;

2) after bending without heating:

for pipes made of carbon, manganese and silico-manganese steels with the wall thickness exceeding 36 mm (regardless of the bending radius) or with the wall thickness of 10 to 36 mm and the mean bending radius less than three-fold outer diameter of the pipe in case out-of-roundness of the bend cross-section exceeds 5%;

for pipes made of 12H1МF and 15HМ1F steel grades with the nominal outer diameter exceeding 108 mm (regardless of the wall thickness) or with the diameter of 108 mm and less and the wall thickness of 12 mm and more;

for pipes made of other alloyed steels in accordance with the PCD;

for pipes having bends with the cross-sectional out-of-roundness exceeding 5%;

3) after welding of parts and assembly units of boilers:

made of carbon, manganese and silico-manganese steels with the wall thickness exceeding 36 mm and with the wall thickness of more than 40 mm in case of concurrent heating up to the temperature of at least 100 °C;

made of other alloyed steel grades in accordance with the PCD;

4) after welding of nozzles and any non-pressurized parts to drums, casings, end plates, headers and pipelines with the basic part wall thickness exceeding the wall thickness specified in subparagraph 3 of this paragraph; welding without heat treatment is permitted subject to use of the special technique approved by the main material research organization;

5) in case additional heat treatment or replacement of the basic heat treatment with additional one is prescribed in the manufacturing and welding documentation as well as in accordance with the requirements of the design and engineering documentation.

158. Conditions for the item within the time period from completion of welding to commencement of tempering (holding time, permissible cooling temperature) shall be determined in the process control documentation. Tempering temperature of a welded item shall not exceed tempering temperature of a semi-finished product.

159. If the prescribed level of mechanical properties for the manufactured component (except for pipe bend) is confirmed by testing the necessity for additional heat treatment as specified in par. 157 of these Rules shall be determined by the boiler developing organization.

160. The necessity for heat treatment and its regime for the components welded of different steel grades shall be defined in the process control documentation.

161. During basic heat treatment of all parts and components as well as additional heat treatment of longitudinal weld joints of shells and pipes and meridional weld joints of elliptical end plates the items shall be heated as a whole. Tempering of items in parts shall be permitted subject to assurance of the required structure and mechanical properties along the entire item length as well as absence of any warpage.

162. Local heat treatment is permitted for austenite conditioning of austenitic steel bends and tempering of bends made of carbon, low-alloyed manganese and silico-manganese steels. Simultaneous heating of the entire bend section and the adjacent straight sections with the length at least equal to three-fold pipe wall thickness but not less than 100 mm at each side of the bend shall be provided in the course of local heat treatment for pipe bends.

163. Tempering of cross-sectional weld joints, shells, headers, pipelines and pipes of boiler heating surfaces as well as weld joints for welding of nozzles, support elements, fasteners and other parts to drums, headers, pipelines and heating surface pipes may be performed by local heating with portable heating devices. Uniform heating along the entire ring perimeter shall be provided in the course of heat treatment for cross-sectional (circular) weld joints. The heating zone width with the weld joint located in the middle of the heated section shall be defined in the process control documentation.

Shell or pipeline sections located near the ring heated in the course of heat treatment shall be covered with insulation in order to assure smooth temperature changes along the entire length.

164. Heat treatment shall be performed in such a way so that to provide uniform heating of metal for the items, its free thermal expansion and absence of any plastic deformations. Heating, holding and cooling regimes in the course of heat treatment for the items with the wall thickness exceeding 20 mm and temperatures exceeding 300 °C shall be registered with self-recording devices.

Control of items and weld joints

165. The following types of control shall be applied in the course of manufacturing, installation, adjustment, repair and refurbishment (retrofitting) of boilers:

1) personnel qualification control;

2) control of assembly and welding, thermal and monitoring equipment, devices, instrumentation and tools;

3) quality control for the basic materials;

4) in-process control of welding techniques;

5) non-destructive quality control for weld joints;

6) destructive quality control for weld joints;

7) defects remedy control.

The above-mentioned types of control shall provide for detection of any unacceptable defects, high quality of products and operational reliability.

Types of control shall be defined by the boiler developing organization in the design and engineering documentation according to the requirements of these Rules and the RD for non-destructive control.

166. The non-destructive control methods for metal and weld joints include:

1) visual and measuring control;

2) radiographic control (radiography);

3) ultrasonic control (USC);

4) liquid penetrant or magnetic powder control;

5) atomic emission spectral analysis (positive material identification test);

6) hardness measurement;

7) metal ball running;

8) hydraulic testing;

9) acoustic emission;

10) eddy current testing.

167. Testing of the mechanical properties, metallographic studies and testing for inter-crystalline corrosion resistance shall be performed within the scope of destructive control.

168. Acceptance control of items, assembly units and weld joints shall be performed after completion of all processing operations associated with the item heating above 450 °C, heat treatment, metal deforming and work-hardening.

Sequence of control by individual methods shall comply with the requirements of the design and engineering documentation. Visual and measuring control and also positive material identification test shall precede any other methods of control.

169. Specialists having passed special theoretical and practical training and proficiency verification and duly admitted to perform the works shall carry out control of weld joints.

170. In the course of works personnel of the organization performing the above-mentioned works shall arrange in-process control of the preparation and assembly of parts for welding, welding and heat treatment of weld joints, elimination of defects in weld joints.

Adherence of the workers to the requirements of these Rules and the design and engineering documentation shall be checked in the course of in-process control. The scope of in-process control in the course of preparation, assembly, welding, heat treatment and elimination of defects shall be specified in the design and engineering documentation.

171. Results for each type of control (including in-process one) and point of control shall be registered in the reporting documents (log sheets, data collection sheets, protocols, certificates).

172. Measuring instruments are subject to metrological calibration.

173. Each batch of defectoscopy materials (penetrants, powders, suspensions, radiographic film, chemical reagents) shall be subject to incoming control prior to use.

174. Control methods and scope for weld joints of weld-on parts not intended for operation under internal pressure shall be specified in the process control documentation.

175. The item shall be deemed suitable in case no internal and surface defects exceeding the acceptable limits according to the quality assessment standards for weld joints stipulated in these Rules and the design and engineering documentation are revealed by any type of control.

Visual and measuring control

176. Visual and measuring control shall be applied to each item and all its weld joints in order to reveal any unacceptable external defects including:

1) any deviations of physical dimensions and mutual alignment of the components;

2) surface cracks of all types and directions;

3) defects on the surface of basic metal and weld joints (particularly dents, splits, cavities, rolls, undercuts, arc strikes, air holes, unfilled craters, lack of penetration, pores and inclusions).

177. Prior to visual control surfaces of the item and weld joints shall be cleaned from any contaminants and slag. The surface of the joint and the adjacent sections of basic metal with the width of at least 20 mm on both sides of the joint (or with the width of at least 100 mm in case of slag welding) shall be cleaned for control of weld joints.

178. Visual and measuring control of items and weld joints shall be performed on the exterior and interior side along the entire length according to the RD for non-destructive control.

In case the inner surface of items and weld joints is not accessible for visual and measuring control it shall be performed only on the exterior side.

179. Any surface defects revealed in the course of visual and measuring control shall be eliminated prior to control by any other non-destructive methods.

180. Allowances for physical dimensions of finished items shall not exceed the values specified in the design and engineering documentation and established in these Rules.

The method and quantity of check measurements and location of the controlled areas shall be defined in the process control documentation.

181. The following deviations are allowed in cylindrical, conical or spherical components made of welded sheets or forged pieces:

1) for the diameter - not more than 1% of the nominal outer or inner diameter;

2) for cross-sectional out-of-roundness - not more than 1%; out-of-roundness shall be calculated in accordance with the following formula:

,

where D_max, D_min are the maximal and the minimal outer or inner diameters measured in the same cross-section;

3) from the generatrix alignment - not exceeding the values specified in the design and engineering documentation for the boiler components.

No local thinnings reducing the wall thickness below the permissible value are allowed.

Depth of dents and any other local shape deviations exceeding the values specified in the design and engineering documentation shall be substantiated by strength calculations.

Cross-sectional out-of-roundness regulated in this paragraph may be increased to 1.5% for the boilers with steam capacity not exceeding 2,5 t/h subject to confirmation by strength calculations.

182. The following dimensional deviations are permitted for dished end plates of boilers:

1) for deviation from the defined shape of the convex section controlled with a templet - not more than 1.25% of the inner end plate diameter in case the inner diameter exceeds 500 mm and not more than 5 mm if the inner diameter is 500 mm or less;

2) for wall thinning caused by stretching in the course of pressing - not more than 10% of the nominal wall thickness unless permissibility of greater thinning is ensured by strength calculations;

3) for the outer or inner diameter - 1% of the nominal diameter from the difference between the maximum and the minimum diameter measured in the same cross-section of the cylindrical edge;

4) for cross-sectional out-of-roundness of the end plate cylindrical edge - not more than 1%.

183. Deviations of the diameter and cross-sectional out-of-roundness for the parts made of pipes shall not exceed the values specified in the design and engineering documentation.

Deflection of horizontal items after completion of all processing operations shall not exceed 6 mm per 1 m of length and 30 mm along the entire length of the item.

184. Wall thickness of bent pipe sections shall be controlled through the use of an ultrasonic thickness gauge or by measurement after cutting performed selectively for a batch of bent sections with the same dimensions. The method, procedure and scope of wall thickness control for bent sections of pipes shall be specified in the process control documentation.

185. Displacement (misalignment) of the edges of welded components (parts) on the exterior side of the joint in butt weld joints of the equipment components and pipelines with the same nominal wall thickness shall not exceed the values specified in Table 2 of these Rules.

Table 2

--------------------------------

<*> Values given in brackets may be permissible only in cases specified on detailed drawings.

Note. In butt weld joints performed by double-sided arc welding as well as by slag welding the above-mentioned displacement of edges shall not be exceeded on both exterior and interior side of the joint.

186. Displacement (misalignment) of edges of components (parts) in butt weld joints with single-side edge preparation on the interior side of the joint (on the weld root side) shall not exceed the norms established by the PCD.

187. The requirements specified in par. 185 and 186 of these Rules shall not be mandatory for weld joints of components (parts) with different actual wall thickness provided that smooth transition from one cross-section to another is arranged by inclination of the coupling surface in accordance with the requirements of par. 36 of these Rules.

In case edges of welded components (parts) are displaced within the limits specified in par. 185 and 186 of these Rules the seam surface shall provide smooth transition from one edge to another.

Radiographic and ultrasonic control

188. Radiographic and ultrasonic control methods shall be used to detect any internal defects of weld joints (cracks, lack of penetration, pores, slag inclusions).

189. Radiographic control and USC of weld joint quality shall be performed in accordance with the process control documentation.

190. The following joints on the items made of pearlitic and martensitic-ferritic steels shall be subject to mandatory USC:

1) all butt joints of drums with the wall thickness of 30 mm and more - along the entire length of joints;

2) all butt weld joints of headers and pipelines with the wall thickness of 15 mm and more - along the entire length of joints;

3) any other weld joints subject to USC in accordance with the PCD requirements.

Only full-penetration joints (without any constructive lack of penetration) shall be subject to USC.

191. The following joints on the items made of pearlitic and martensitic-ferritic steels shall be subject to USC or radiographic control:

1) all butt weld joints of drums with the wall thickness of less than 30 mm - along the entire length of joints;

2) all butt weld joints of headers with the wall thickness of less than 15 mm - along the entire length of joints;

3) all butt weld joints of pipelines with the outer diameter of 200 mm and more and the wall thickness of less than 15 mm - along the entire length of joints;

4) butt weld joints performed by arc or gas welding on the boiler pipelines with the outer diameter of less than 200 mm and the wall thickness of less than 15 mm within the following scope:

for boilers with the working pressure exceeding 4 MPa - at least 20% (but not less than five butt joints) of the total number of similar butt joints on each boiler performed by each welding operator, along the entire length of joints;

for boilers with the working pressure of 4 MPa and less - at least 10% (but not less than five butt joints) of the total number of similar butt joints on each boiler performed by each welding operator, along the entire length of joints;

5) all butt weld joints performed by arc or gas welding on the heating surface tubes with the working pressure of 10 MPa and more - along the entire length of joints, and in case the butt joint is partially inaccessible for control - along the length of at least 50% of the joint perimeter;

6) butt weld joints performed by arc or gas welding on the heating surface tubes with the working pressure of less than 10 MPa - at least 5% (but not less than five butt joints) of the total number of similar butt joints on each boiler (superheater, economizer) performed by each welding operator at the length of at least 50% of each controlled joint perimeter;

7) all weld joints of drums and headers with nozzles with the inner diameter of 100 mm and more regardless of the wall thickness - along the entire length of joints;

8) butt weld joints of cast elements, pipes with cast parts as well as any other weld joints (including corner and T-shaped ones) not specified in subparagraphs 1-7 of this paragraph - at least 3% (but not less than two butt joints) of the total number of similar butt joints on each boiler performed by each welding operator along the length of at least 30% of each controlled joint perimeter.

The control method (USC or radiographic control) for the weld joints specified in this paragraph shall be selected on the basis of the possibility to assure more complete and accurate detection of defects with due regard for peculiar physical properties of metal as well as familiarization and excellence of the control method for this type of weld joints on particular items.

192. All coupling sites of longitudinal and cross-sectional butt weld joints on drums and headers subjected to USC in accordance with par. 190 of these Rules shall be subject to mandatory radiographic control.

193. The following joints on the items made of austenitic steels as well as at the coupling sites between components made of austenitic steels and components made of pearlitic or martensitic-ferritic steels shall be subject to mandatory radiographic control:

1) all butt weld joints of drums and headers - along the entire length of joints;

2) all butt weld joints of pipelines except for the ones performed by resistance butt welding - along the entire length of joints;

3) butt weld joints performed by arc welding on the heating surface tubes - at least 10% (but not less than ten  butt joints) of the total number of similar butt joints on each boiler (superheater, economizer) performed by each welding operator along the entire length of joints, and in case the butt joint is partially inaccessible for control - along the length of at least 50% of the joint perimeter;

4) all butt weld joints of cast components as well as pipes with cast elements - along the entire length of joints;

5) all weld joints of drums and headers with nozzles with the inner diameter of 100 mm and more regardless of the wall thickness - along the entire length of joints;

6) weld joints (including corner and T-shaped ones) not specified in subparagraphs 1-5 of this paragraph - at least 3% (but not less than two butt joints) of the total number of similar butt joints on each boiler (superheater, economizer) performed by each welding operator along the length of at least 30% of each controlled joint perimeter.

194. Butt weld joints subjected to repair re-welding shall be checked by radiographic control or USC along the entire length of weld joints. Areas repaired through the use of gouge welding shall be checked by radiographic control or USC across the entire sections including heat-affected zone in the basic metal. The surface of the section shall be also checked by magnetic powder or liquid penetrant inspection. In case of seal welding across the entire wall thickness surface shall be controlled from both sides except for the cases when the interior side is inaccessible for control.

195. USC of a butt weld joint shall be performed on both sides of the weld joint except for weld-on joints of flat end plates, valves and other joints accessible for control only from one side of the weld joint.

196. In case it is impossible to perform USC or radiographic control due to inaccessibility of individual weld joints or the above-mentioned control methods are inefficient (particularly for weld-on joints of nozzles and pipes with the diameter of less than 100 mm) quality control for these weld joints shall be performed by layer-by-layer visual control in the course of welding with registration of the control results in a special-purpose log and complete layer-by-layer liquid penetrant or magnetic powder control of the finished weld joint.

197. In case of selective control (with the control scope of less than 100%) at least three sections of each weld joint shall be checked.

It is permitted to define the scope of selective control for cross-sectional butt joints and corner joints of pipes or nozzles with the nominal size of 250 mm and less for the entire length of similar weld joints performed by each welding operator at each boiler or pipeline. In this case the number of controlled joints shall be not less than five; each joint shall be checked along the entire length.

In case of selective control choice of controlled weld joints or sections out of the most difficult or doubtful subsequent to the results of visual and measuring control shall be performed by the technical control department of the organization.

198. In case any defects are detected in the course of selective control of the weld joints performed by any welding operator all similar weld joints performed by this welding operator on the item (boiler or pipeline) within the period that has passed from the previous control of the item weld joints by the same method shall be subject to control along the entire length.

199. The possibility to replace radiographic control and USC with any equivalent control methods shall be approved by the boiler developing organization and the main material research organization.

Liquid penetrant and magnetic powder control

200. Liquid penetrant and magnetic powder control of weld joints and items is an additional method of control established in the process control documentation in order to detect any surface or sub-surface defects.

201. Liquid penetrant and magnetic powder control shall be performed in accordance with the control methods approved for application by the boiler developing organization and the main material research organization.

202. Class and sensitivity level of liquid penetrant and magnetic powder control shall be specified in the design and engineering documentation.

Positive material identification test

203. Positive material identification test shall be performed in order to confirm compliance of metal alloying for weld joints and components of pressurized equipment with the requirements of drawings and process control documentation.

204. The following elements shall be subject to positive material identification testing:

1) all welded parts (structural elements) to be made of alloyed steel in accordance with the design and engineering documentation;

2) weld metal of all weld joints to be performed with the use of alloyed filler in accordance with the design and engineering documentation;

3) welding materials specified in par. 142 of these Rules.

205. Positive material identification testing shall be performed in accordance with the RD requirements.

Hardness measurement

206. Weld joint metal hardness measurement is performed in order to check quality of heat treatment for weld joints.

207. Weld metal of weld joints made of alloyed heat-resistant steels of pearlitic and martensitic-ferritic classes shall be subject to hardness measurement through the use of methods and within the scope specified in the process control documentation.

Metal ball running control

208. Metal ball running control shall be performed in order to check for burr removal completeness or absence of excessive reinforcement of the joint from the inside and assurance of the required flow area in weld joints of the heating surface tubes.

209. Weld joints of heating surfaces shall be subject to metal ball running control in any cases prescribed in the design and engineering documentation.

210. Diameter of the control ball shall be specified in the process control documentation.

Mechanical testing, metallographic studies

and inter-crystalline corrosion resistance tests

211. Mechanical tests shall be performed in order to check compliance of the mechanical characteristics and quality of weld joints with the requirements of design and engineering documentation and the PCD.

Metallographic studies shall be performed in order to detect any potential internal defects (cracks, lack of penetration, pores, slag and non-metal inclusions) and also sections with metal structure deteriorating the properties of weld joints.

Inter-crystalline corrosion resistance tests shall be performed in any cases prescribed by the process control documentation in order to confirm corrosion resistance of weld joints on the parts made of austenitic steels.

Mechanical testing, metallographic studies and inter-crystalline corrosion resistance tests shall be performed in accordance with the regulatory documentation.

212. Mechanical testing shall be performed:

1) for the welding technique validation;

2) to control the manufacturing butt weld joints of: elements of shells, end plates and tube sheets with longitudinal and cross-sectional weld joints; elements of pipes with cross-sectional weld joints performed by gas and resistance welding;

3) during incoming control of welding materials used for flux and slag welding.

213. Metallographic studies shall be performed:

1) for the welding technique validation;

2) to control the manufacturing butt weld joints of: elements of shells, end plates and tube sheets with longitudinal and cross-sectional weld joints; elements of pipes with cross-sectional weld joints performed by gas and resistance welding; parts made of steels with different structural classes;

3) to control manufacturing corner and T-shaped weld joints particularly joints between pipes (nozzles) and shells, drums, headers, pipelines as well as tee joints.

214. The main types of mechanical tests include static tension tests, static bending tests or flattening and impact bending tests.

Static tension tests are not mandatory for manufacturing cross-sectional weld joints subject to complete radiographic control or USC of these joints.

Impact viscosity tests are not mandatory for manufacturing weld joints of the parts operated under the pressure of less than 8 MPa and the design wall temperature not exceeding 450 °C as well as for all weld joints of the parts with the wall thickness of less than 12 mm.

215. Metallographic studies are not mandatory for the following weld joints:

1) on the parts made of pearlitic steel subject to complete radiographic control or USC of these joints;

2) on the surface heating tubes and pipelines performed by resistance welding with the use of special-purpose machines for resistance butt welding of boiler tubes with automated operation cycle subject to the machine adjustment quality check on a shift basis through reference sample testing.

216. Mechanical testing, metallographic studies and inter-crystalline corrosion resistance tests shall be performed on the samples made of manufacturing weld joints cut out of the items or reference weld joints (see Appendix 2 to these Rules).

217. Reference weld joints shall be identical to controlled manufacturing joints and performed in full compliance with the process applied for welding of manufacturing joints or production validation of the technique. Heat treatment of the reference joints shall be performed together with the item (for common heat treatment in the furnace) and in case it is impossible - separately through the use of heating and cooling methods and temperature regimes specified in the process control documentation for manufacturing joints. In case controlled weld joints are subjected to repeated heat treatment the reference joint shall be subjected to the same number of heat treatments under the same regimes. In case a manufacturing joint is subjected to repeated high-temperature tempering the reference joint may be subjected to single tempering with the holding time of at least 80% of the total holding time in the course of all high-temperature temperings of the manufacturing joint.

218. Reference weld joints shall be arranged as:

1) butt joints of plates - to control joints of shells, dished and flat end plates and tube sheets;

2) butt joints of two pipe sections - to control joints of pipelines and boiler heating surface tubes;

3) corner or T-shaped joints between sheets and pipes - to control welding of nozzles to shells and end plates;

4) corner or T-shaped joints between nozzles (pipe sections) and the main pipes - to control welding of nozzles to pipelines or headers and also for tee joints.

219. The reference weld joint shall be completely controlled by the same non-destructive control methods as provided for manufacturing weld joints. In case the control results are unsatisfactory the reference joints shall be manufactured again in double quantity. In case the results of repeated non-destructive control are unsatisfactory the general result shall be also deemed unsatisfactory. In this case quality of materials, equipment and qualification of the welding operator shall be subject to additional check.

220. At least one reference weld joint for all similar manufacturing joints performed by each welding operator within six months (particularly for different orders) shall be made for control of manufacturing butt weld joints in accordance with subparagraph 2, par. 212 and subparagraph 2, par. 213 of these Rules unless increased number of reference joints is prescribed in the design and engineering documentation. In case of any off-the-job period for any welding operator exceeding three months a new reference weld joint shall be made and checked.

When controlling cross-sectional joints of pipes performed by resistance welding at least two reference joints shall be tested for all identical manufacturing joints welded on each welding machine with automated operation cycle within a shift and in case of the machine readjustment during a shift - within the period between readjustments.

When controlling cross-sectional joints of pipes with the nominal size of less than 100 mm and the wall thickness of less than 12 mm performed on special-purpose machines for resistance welding of boiler tubes with automated operation cycle and the machine adjustment quality check on a shift basis through accelerated reference sample testing it is permitted to test at least two reference weld joints for the products manufactured within the period not exceeding three days provided that pipes with the same dimensions and the same steel grades are welded under constant conditions with identical end preparation.

221. Dimensions and quantity of reference joints shall be sufficient to manufacture a set of samples for testing. The minimal number of samples for each type of testing shall be the following:

1) two samples for static tension testing;

2) two samples for static bending testing;

3) three samples for impact bending testing;

4) one sample (thin section) for metallographic studies to control weld joints made of carbon and low-alloyed steel and at least two - to control weld joints made of high-alloyed steel in cases prescribed by the process control documentation;

5) two samples for inter-crystalline corrosion resistance testing.

Static bending testing of reference joints on pipes with the outer diameter not exceeding 108 mm may be replaced with flattening testing. Flattening tests shall be performed in the cases prescribed in the design and engineering documentation.

222. If the results of any mechanical test are unsatisfactory the test can be repeated for a double number of samples cut from the same reference weld joints for the type of testing which has given unsatisfactory results.

In case parameters not complying with the established standards are obtained for at least one of the samples in the course of repeated testing the general results of this testing type shall be deemed unsatisfactory.

In case it is impossible to cut samples out of the first reference joint (set) the second reference joint (set) may be welded in accordance with the above-mentioned requirements.

Quality assessment norms

223. The quality control system for the performed works shall be applied in the course of manufacturing, installation, adjustment, repair or refurbishment (retrofitting) of boilers in order to eliminate any defects deteriorating reliability and safety of the boiler operation.

224. Allowances for dimensions of the finished items shall comply with the requirements of the design and engineering documentation.

225. Quality of weld joints shall comply with the quality assessment standards for weld joints stated in these Rules and the design and engineering documentation.

Hydraulic testing

226. Hydraulic testing shall be performed in order to check strength of the boiler, superheater and economizer components as well as leak-tightness of all welds and other joints.

All boilers, superheaters, economizers and their components shall be subject to hydraulic testing under test pressure after their manufacturing and after repair and refurbishment (retrofitting) involving any welding works.

The operating organization shall carry out hydraulic testing under working pressure each time after opening of the drum or header or repair of the boiler provided that the nature and scope of repair does not necessitate unscheduled examination.

Boilers with manufacturing completed at the installation site transported to the installation site in separate parts, components or units shall be subject to hydraulic testing at the installation site.

The boiler shall be presented for hydraulic testing with all valves installed.

The following boiler components are subject to hydraulic testing:

1) all tubular, welded, cast, shaped and other components and parts as well as valves unless they have been subjected to hydraulic testing at their manufacturing plants (hydraulic testing of the above-mentioned components and parts is not mandatory provided that they are subjected to complete USC or any other equivalent non-destructive control);

2) assembled boiler components (drums and headers with weld-on nozzles or tubes, heating surface and pipeline assemblies) (hydraulic testing of headers and pipeline assemblies is not mandatory provided that all constituent elements thereof have been subjected to hydraulic testing or complete USC or radiographic control and all weld joints performed during manufacturing of the prefabricated components have been checked by the above-mentioned control methods along the entire length);

3) boilers, superheaters, economizers after their manufacturing, installation, adjustment, repair or refurbishment (retrofitting) involving any welding works.

Hydraulic testing of individual and assembled components together with the boiler is permitted in case it is impossible to test them separately under the conditions of manufacturing, repair or refurbishment (retrofitting) of the boiler.

227. The minimum test pressure P_h for hydraulic testing of boilers as well as pipelines within boilers shall be assumed as follows:

1) at the working pressure P not exceeding 0,5 MPa:

P_h=1.5P, but not less than 0,2 MPa;

2) at the working pressure P exceeding 0,5 MPa:

P_h = 1.25P, but not less than P+0.3 MPa.

In case of the working pressure reduction subsequent to the results of the previous technical inspection the test pressure for hydraulic testing shall be determined on the basis of the permitted pressure.

In the course of hydraulic testing of drum boilers as well as their superheaters and economizers the pressure in the boiler drum shall be assumed as the working pressure and for drumless and direct-flow forced-circulation boilers - the feedwater pressure at the boiler inlet specified in the design and engineering documentation.

The maximum test pressure shall be defined by strength calculations with due regard for hydrostatic pressure.

The test pressure value shall be defined by the boiler developing organization within the specified limits and shall provide the maximal detectability of defects in the component subjected to hydraulic testing.

228. Hydraulic testing of the boiler, its components and separate items shall be performed subsequent to heat treatment and all types of control as well as elimination of the revealed defects.

229. The boiler developing organization shall specify the minimum wall temperature during hydraulic testing in the course of the boiler operation in the boiler installation and operation manual according to the conditions for brittle failure prevention.

Hydraulic testing shall be performed using water with the temperature of not less than 5 °C and not more than 40 °C. The upper water temperature limit may be increased to 80 °C in accordance with the decision of the boiler developing organization in case it is necessary due to characteristics of metal.

Temperature difference between metal and the ambient air shall not cause any moisture condensation on the boiler surface. Water used for hydraulic testing shall be subjected to pre-boiler treatment and shall not contaminate the boiler or cause intensive corrosion.

It is prohibited to use raw (service) water for hydraulic testing.

230. In the course of the boiler filling with water air shall be removed from inner cavities. Pressure should be gradually increased up to the test value.

The total pressure increase time shall be specified in the boiler installation and operation manual. In case no pressure increase time is specified in the manual it shall be at least 10 minutes.

The holding time under the test pressure shall be at least 10 minutes.

Subsequent to holding under the test pressure pressure shall be reduced to the working value and inspection of all welded, expanded, riveted and detachable joints shall be performed.

Water pressure in the course of testing shall be controlled with two calibrated pressure gauges of the same type, measurement range, grade of accuracy (not less than 1.5) and scale interval installed on different boiler components. It is not permitted to use compressed air or any other gas to raise pressure.

231. The item shall be deemed to pass the test if none of the following defects are detected:

1) leaks, cracks, seepage in weld joints and basic metal;

2) leaks in expanded and detachable joints;

3) any visible residual deformations;

4) gauge pressure drop.

Appearance of separate drops not increasing in size with the lapse of time is permitted for expanded and detachable joints.

232. Water removal shall be arranged subsequent to completion of hydraulic testing.

233. Hydraulic testing may be performed simultaneously for several components of the boiler, superheater or economizer or for the entire item subject to compliance with the following conditions:

1) the test pressure in each of the combined components shall be at least equal to the value specified in par. 227 of these Rules;

2) complete non-destructive control of basic metal and weld joints of the components where the test pressure is assumed to be below the values specified in par. 227 of these Rules shall be provided.

Elimination of defects in weld joints

234. Any defects revealed in the course of manufacturing, installation, adjustment, testing and operation of the boiler shall be eliminated with subsequent control of the repaired areas.

235. Defect elimination techniques and the control procedure shall be specified in the process control documentation.

236. Defects shall be eliminated mechanically with arrangement of smooth transition at the weld defect elimination sites. Maximum size and shape of gouges to be welded shall be established in the process control documentation.

Thermal cutting (gouging) techniques may be used for removal of internal defects with subsequent mechanical processing of the weld defect elimination surface.

Completeness of defect elimination shall be checked visually and by non-destructive control methods (liquid penetrant or magnetic powder control or etching).

237. Elimination of defects without any weld-up of the defect elimination sites is permitted subject to maintenance of the minimum permissible wall thickness at the maximum gouging depth point.

238. In case any defects are revealed during control of the repaired section repeated elimination of defects may be performed in accordance with the same procedure as the first one.

Elimination of defects at the same section of a weld joint may be performed not more than three times.

Joints cut along the weld seam with removal of weld metal from the heat-affected zone shall not be considered as repeatedly repaired.

In case a defective weld joint of pipes is cut out and then an insert in the form of a pipe section is welded in the two newly performed weld joint shall not be considered as repaired.

Certificate and labelling

239. Each boiler, self-contained superheater and economizer shall be supplied by the manufacturing organization with a certificate and an operation manual. The requirements for contents of the boiler certificate are given in Appendix 3 to these Rules.

Boiler components (particularly drums, headers, pipe bends) shall be supplied by the manufacturing organization with a manufacturing quality certificate containing information in accordance with the requirements of the relevant sections of the certificate.

240. The following data shall be inscribed by stamping on the drum end plates or boiler casings as well as on headers (with due regard for the requirements of par. 139 of these Rules):

1) name or trademark of the manufacturing organization;

2) serial number of the item;

3) year of manufacture;

4) design pressure in MPa;

5) design wall temperature in °C and steel grade (only for superheater headers).

Particular places for application of the above-mentioned data shall be selected by the manufacturing organization and specified in the boiler installation and operation manual.

241. A nameplate with the nominal data inscribed by impact method shall be attached to each boiler, self-contained superheater and economizer. Labelling by mechanical, electrographic or electrochemical method ensuring image legibility and durability equivalent to the impact method is permitted.

242. The following data shall be indicated on the steam boiler nameplate:

1) name and trademark of the manufacturing organization;

2) boiler designation in accordance with the national standards;

3) boiler number in accordance with the numbering system of the manufacturing organization;

4) year of manufacture;

5) rated capacity, t/h;

6) working pressure at the outlet, MPa;

7) rated steam temperature at the outlet, °C.

243. The following data shall be indicated on the hot water boiler nameplate:

1) name and trademark of the manufacturing organization;

2) boiler designation in accordance with the national standards;

3) boiler number in accordance with the numbering system of the manufacturing organization;

4) year of manufacture;

5) rated heating capacity, GJ/h (Gcal/h);

6) working pressure at the outlet, MPa;

7) rated water temperature at the outlet, °C.

244. The following data shall be indicated on the self-contained superheater nameplate:

1) name and trademark of the manufacturing organization;

2) superheater number in accordance with the numbering system of the manufacturing organization;

3) year of manufacture;

4) rated steam capacity, t/h;

5) working pressure at the outlet, MPa;

6) steam temperature at the outlet, °C.

245. The following data shall be indicated on the self-contained economizer nameplate:

1) name and trademark of the manufacturing organization;

2) economizer number in accordance with the numbering system of the manufacturing organization;

3) year of manufacture;

4) maximum working pressure in the economizer, MPa.

V. Valve, instrumentation and feeding devices

5.1. General

246. Boilers shall be equipped with the following devices for control of operation and assurance of safe conditions and design operation modes:

1) devices for protection against overpressure (protection devices);

2) water level indicators;

3) working medium pressure measuring devices;

4) medium temperature measuring devices;

5) shutoff and control valves;

6) safety devices;

7) feeding devices.

247. The required quantity of valves, measuring and automation devices and protections to ensure adjustment of operation modes, monitoring of parameters, boiler shutdown, reliable operation, safe maintenance and repair shall be provided in the design and engineering documentation.

248. Equipment of the boiler with instrumentation shall be defined in the design and engineering documentation.

Protection devices

249. Each boiler component with the internal volume limited by shutoff devices shall be protected with protection devices automatically preventing pressure increase above the permissible value by release of the working medium to the atmosphere or to the disposal system.

250. The necessity, quantity and dimensions of safety valves for the first section of direct-flow steam boilers where the first (along the water flow) section of the heating surface is isolated from the rest of the heating surface by shutoff devices in the course of the boiler start-up or shutdown shall be defined by the boiler manufacturing organization.

251. The following devices may be used as protection ones:

1) direct-action dead-weight safety valves;

2) direct-action spring-loaded safety valves;

3) pilot-operated relief valves (hereinafter - PORV) consisting of a pilot operated valve (hereinafter - POV) and a main safety valve (hereinafter - MSV).

Use of any other protection devices shall be permitted subject to approval of the boiler developing organization and the operating organization.

252. Only pilot operated safety valves shall be installed on steam boilers with the pressure exceeding 4 MPa (except for mobile boilers and boilers with the steam capacity below 35 t/h); spring-loaded safety valves shall be installed on mobile boilers and boilers with the steam capacity below 35 t/h.

The inside diameter (nominal) of dead-weight and spring-loaded valves shall be at least 20 mm.

The nominal inside diameter of valves may be reduced to 15 mm for boilers with the steam capacity below 0.2 t/h and pressure of less than 0.8 MPa subject to installation of two valves.

253. At least two protection devices shall be installed on each steam and hot water boiler and the superheater isolated along the working medium line.

It is permitted not to install safety valves and PORVs on hot water boilers with in-chamber combustion of fuel equipped with automatic devices in accordance with par. 324 of these Rules.

254. The nominal inside diameter of tubes connecting the POV with the PORV MSV shall be at least 15 mm.

255. The aggregate flow capacity of protection devices installed on a steam boiler shall be at least equal to the rated steam capacity of the boiler.

Flow capacity of protection devices shall be checked by the relevant calculations.

256. Flow capacity of safety valves shall be confirmed by the relevant type testing for this valve design performed by the valve manufacturing organization and specified in the valve certificate.

257. Protection devices shall be installed:

1) in steam boilers with natural circulation without a superheater - on the upper drum or steam dome;

2) in direct-flow steam boilers as well as in forced-circulation boilers - on the outlet header or output steam pipeline;

3) in hot water boilers - on the outlet headers or on the drum;

4) in intermediate superheaters - all superheater protection devices may be installed on the steam inlet side;

5) in economizers isolated along the water line - at least one protection devices at the water inlet and outlet.

258. In case the boiler is equipped with a non-isolable superheater some safety valves with the flow capacity of at least 50% of the rated boiler capacity shall be installed on the outlet header of the superheater.

259. Indirect-action POVs shall be installed in steam boilers with the working pressure exceeding 4 MPa on the outlet header of the non-isolable superheater or on the steam pipeline upstream of the main shutoff device; in this case in drum boilers pulse steam extraction for 50% of valves by aggregate flow capacity shall be arranged from the boiler drum.

In case of odd quantity of identical valves it is permitted to arrange pulse steam extraction from the drum for at least 1/3 and not more than 1/2 of the valves installed on the boiler.

On unit plants it is permitted to use superheated steam for pulses of all valves if the valves are installed on the steam pipeline immediately near the turbines; in this case additional electric impulse shall be supplied for 50% of valves from a contact pressure gauge connected to the boiler drum.

In case of odd quantity of identical valves it is permitted to supply additional electric impulse from a contact pressure gauge connected to the boiler drum for at least 1/3 and not more than 1/2 of the valves installed on the boiler.

260. Safety valves with the flow capacity at least equal to the maximum amount of steam supplied to the intermediate superheater shall be installed at power units with steam reheating after the high pressure cylinder of the turbine (hereinafter - the HPC). In case of any shutoff valves downstream of the HPC additional safety valves shall be installed. The above-mentioned valves shall be designed with due regard for both aggregate flow capacity of the pipelines connecting the intermediate superheater system with the higher pressure sources not protected by their own safety valves at the reheating system inlet and any potential steam leakages that may be caused by any damage of high-pressure pipes of steam and gas-steam heat exchangers for steam temperature control.

261. Places for installation of safety valves in isolable economizers, the method for their adjustment and opening pressure values shall be specified by the manufacturing organization in the economizer certificate.

262. The adjustment method and frequency for safety valves in boilers, superheaters and economizers as well as their initial opening pressure shall be specified by the manufacturing organization in the boiler installation and operation manual.

The minimal design pressure for low-temperature components of the reheating system shall be assumed as the design pressure to determine opening initiation for safety valves installed on the cold reheat steam pipelines.

263. Safety valves shall protect boilers, superheaters and economizers against overpressure exceeding 10% of the design (permitted) value.

Overpressure exceeding 10% of the design value with complete opening of safety valves may be allowed only in case when it is provided in the strength calculation of the boiler, superheater and economizer.

264. Extraction of medium from any nozzle or pipeline connecting a protection device with the protected component is prohibited.

265. Protection devices shall be installed on nozzles or pipelines connected directly to the protected item.

266. Installation of shutoff devices on the steam supply lines to valves and on the pipelines between POVs and PORV MSVs is prohibited.

267. Design of dead-weight or spring-loaded valves shall provide for the device to check operability of the valve in the course of the boiler operation by its forced opening.

PORVs shall be equipped with the device enabling remote forced opening of valves from the control panel.

268. Design of spring-loaded valves shall eliminate the possibility for the spring tensioning in excess of the specified value. Valve springs shall be protected against direct impact of exhausted steam jets.

269. Safety valves shall have discharge pipelines protecting the personnel against burns upon actuation of the valves. These pipelines shall be protected from freezing and equipped with drains for discharge of accumulated condensate. Installation of shutoff devices on drains is not permitted.

270. The water discharge pipe from safety valves of the hot water boiler, economizer shall be connected to the free water drain line. Installation of shutoff devices on the water discharge pipe and the drain line is not permitted. Arrangement of the water discharge system and the free drain lines shall eliminate any possibility of burns for people.

271. Safety valves shall be supplied to the customer together with the certificates including characteristics of their flow capacity.

Water level indicators

272. At least two direct-action water level indicators shall be installed on each steam boiler except for direct-flow ones. Indirect-action water level indicators may be additionally installed as redundant ones. Number and places of installation of water level indicators in the boilers particularly the ones with step evaporation in drums or an outside-mounted separator shall be determined by the boiler developing organization.

272. Each water level indicator shall have independent connection to the boiler drum. Two water level indicators may be installed on the connection pipe (stand-pipe) with the diameter of at least 70 mm.

In case water level indicators are connected to the boiler through the use of pipes with the length of up to 500 mm their inner diameter shall be at least 25 mm and with the length exceeding 500 mm - at least 50 mm. Installation of any intermediate flanges and shutoff devices (except for liquid level alarms) on these pipes is not permitted. This requirement shall not be applicable to flanges of shutoff devices forming a part of the water level indicator.

274. Connection of any other instrumentation to direct-action level indicators and their connecting pipes or nozzles is not permitted except for a water level alarm sensor provided that operation of the level indicator is not impaired.

275. Configuration of the pipes connecting water level indicators with the boiler shall eliminate formation of any water pockets inside them and provide for the possibility to clean the pipes. Connecting pipes shall be protected against thermal heating with fuel combustion products and against freezing.

276. Only clear flat plates shall be used in direct-action level indicators for steam boilers. Usage of corrugated plates as well as plates with smooth surface on both sides is permitted for boilers with the working pressure below 4 MPa. Smooth plates with mica spacers protecting the plates against direct impact of water and steam or sets of mica plates shall be applied for boilers with the working pressure exceeding 4 MPa. Usage of sight plates without mica protection is permitted in case their material is resistant to corrosive impacts of water and steam under the relevant temperature and pressure.

In case of outdoor installation of waste heat boilers and industrial power boilers mica plates or glass plates protected with mica plates on both sides shall be used in direct-action water level indicators. Application of glass plates is permitted only subject to level indicators installation in heated cabinets.

277. Direct-action water level indicators shall be installed vertically or with forward pitch not exceeding 30° and shall be located and lighted so that the water level could be seen clearly from the boiler operator workplace.

278. Direct-action level indicators on boilers with the pressure exceeding 4 MPa shall be equipped with casings in order to protect the personnel against breakage of clear plates.

279. Width of the vision port for a water level indicator shall be at least:

1) 8 mm - in case clear glass plates are used;

2) 5 mm - in case mica plates are used.

280. Water level indicators shall be equipped with shutoff devices (cocks or valves) in order to isolate them from the boiler for blowdown.

Opening and closing directions shall be clearly indicated (cast, stamped or painted) on the shutoff valves and position of the port shall be indicated on the cock. The inner flow diameter of shutoff valves shall be at least 8 mm.

Funnels with protective devices and the free draining discharge pipe shall be provided for water drainage during blowdown of water level indicators.

281. In case pressure in the drum exceeds 4,5 MPa water level indicators shall be equipped with two shutoff devices installed in series for their isolation from the boiler.

A cock with a taper plug may be used as a shutoff device for boilers with the working pressure below 1,3 MPa.

282. A test cock installed in the top section of the boiler drum and in the absence of any drum - at the water outlet from the boiler to the main pipeline upstream of the shutoff devices shall be arranged on hot water boilers.

283. Height of the clear element of a water level indicator shall exceed the permissible water level limits by at least 25 mm on each side.

The permissible upper and lower levels shall be indicated on each direct- and indirect-action water level indicator.

284. In case water level indicators consisting of several individual water-gauge plates are installed the latter shall be located in such a way so that to show water level in the boiler continuously.

285. In case the distance from the site where observation of water level in a steam boiler is arranged to direct-action water level indicators exceeds 6 m and the instrument readings are poorly visible two remote water level indicators shall be installed. In this case one direct-action water level indicator may be installed on the boiler drums.

Remote level indicators shall be connected to the boiler drum with individual nozzles independent from any other water level indicators and shall be equipped with damping devices.

For waste heat boilers and industry power boilers remote level indicators shall be installed on the boiler control panel.

Working medium pressure measuring devices

286. A steam pressure monitoring device shall be installed on each steam boiler: direct-action devices with in-situ indication (pressure gauges, sensors) or secondary hardware for remote transmission, processing and presentation of pressure data.

In case pressure gauges are used as pressure monitoring devices on steam boilers with the steam capacity exceeding 10 t/h and hot water boilers with heating capacity of more than 21 GJ/h (5 Gcal/h) installation of a sensor with information output to the recording device shall be mandatory.

Pressure monitoring devices shall be installed on the boiler drum and in case the boiler is equipped with a superheater - downstream of the superheater and upstream of the main gate valve.

For direct-flow boilers pressure monitoring devices shall be installed downstream of the superheater and upstream of the shutoff device.

Installation of pressure monitoring devices on superheaters of shell-type and vertical boilers is not mandatory.

287. A pressure monitoring device shall be installed for each steam boiler on the feeding line upstream of the boiler feedwater supply controlling device.

In case several boilers with the steam capacity of less than 2,5 t/h each are installed in the boiler house one pressure monitoring device may be installed on the common feeding line.

288. In case the water supply system is used instead of the second feeding pump  a pressure monitoring device shall be installed on this water supply system in the nearest vicinity of the boiler.

289. For economizers isolated along the water supply line pressure monitoring devices shall be installed at the water inlet and outlet upstream of the shutoff device and the safety valve.

In case any pressure monitoring devices are available on the common feeding lines upstream of economizers their installation at the water inlet of each economizer is not mandatory.

290. Pressure monitoring devices for hot water boilers shall be installed at the water inlet and at the hot water outlet upstream of the shutoff device, on the suction and discharge lines of circulation pumps with location at the same elevation as well as on the boiler feeding lines or the heating system makeup lines.

291. In case pressure gauges are used as pressure monitoring devices their grade of accuracy shall be at least:

1) 2.5 - for the working pressure of up to 2.5 MPa;

2) 1.5 - for the working pressure exceeding 2.5 MPa and up to 14 MPa;

3) 1.0 - for the working pressure exceeding 14 MPa.

292. A pressure gauge shall be selected with such measurement range so that the working pressure measurement limit is in the second third part of the range (scale).

293. A red line shall be marked on the pressure gauge scale (at the graduation line corresponding to the working pressure for this component with due regard for additional pressure from liquid column weight). Instead of the red line a plate painted with red and tightly fitted on the pressure gauge glass (or self-adhesive film covering the pressure gauge casing in order to prevent the glass displacement) may be attached to the pressure gauge casing.

294. The installation diagram for the pressure gauges shall ensure the possibility of their operability check, maintenance, repair and replacement as well as the possibility for the operating personnel to see their readings clearly.

The nominal diameter of pressure gauges installed at the height of up to 2 m from the pressure gauge service platform level shall be at least 100 mm: at the height of 2 to 5 m - at least 160 mm, at the height of more than 5 m - at least 250 mm.

In case a pressure gauge is installed at the height exceeding 5 m a redundant pressure gauge shall be installed at the height ensuring clear visibility of the pressure gauge readings.

295. A three-way cock or any other similar device shall be installed upstream of each pressure gauge for the purpose of the pressure gauge blowdown, inspection and isolation. A siphon pipe with the nominal diameter of at least 10 mm shall be also installed upstream of any pressure gauge intended for steam pressure measurement.

Valves enabling to isolate the pressure gauge from the boiler, connect it to the atmosphere and carry out the siphon pipe blowdown shall be installed on boilers with the pressure of 4 MPa and more instead of three-way cocks.

296. Pressure gauges shall not be permitted for use in the following cases:

1) there is no seal or stamp with the calibration record on the pressure gauge;

2) the pressure gauge calibration term has expired;

3) the pressure gauge hand will not return to the zero scale mark when it is turned off by more than half of the permissible error for this pressure gauge;

4) glass is broken or there are any other damages of the pressure gauge capable of affecting correctness of its readings.

297. Calibration of pressure gauges with their sealing and stamping shall be performed at least once per 12 months.

Additional verification of the operating pressure gauges through the use of a reference pressure gauge shall be performed at least once per six months with registration of the results in the verification inspection log sheet. If no reference pressure gauge is available additional verification may be performed through the use of a calibrated operating pressure gauge with the same measurement range and accuracy grade as the device being verified.

The procedure and time limits for inspection of the pressure gauge operability by the operating personnel in the course of the boiler operation shall be specified in the manual approved by the operating organization management.

Verification of pressure gauges through the use of a reference pressure gauge may be replaced with calibration once per six months.

Temperature measurement devices

298. For boilers with superheaters a device for superheated steam temperature measurement shall be installed on each steam pipeline upstream of the main gate valve. For boilers with steam reheating temperature measurement devices shall be installed at the steam inlet and outlet.

299. Devices with continuous superheated steam temperature recording shall be installed on natural-circulation boilers, boilers with steam superheating and steam capacity exceeding 20 t/h and direct-flow boilers with steam capacity exceeding 1 t/h apart from the indication devices.

300. For superheaters with several parallel sections instrumentation for regular steam temperature measurement shall be installed at the outlet of each section apart from steam temperature measurement devices installed on the common superheated steam pipelines; and for boilers with the steam temperature exceeding 500 °C at the outlet section of superheater coils a thermocouple (sensor) shall be installed per each meter of the gas duct width.

Devices for measurement of steam temperature at the outlet section of superheater coils of the boilers with steam capacity exceeding 400 t/h shall be continuously-operated and equipped with recorders.

301. In case the boiler is equipped with a steam cooler for steam superheating temperature control steam temperature measuring devices shall be installed upstream and downstream of the steam cooler.

302. Feedwater temperature measuring devices shall be installed at the water inlet and outlet of the economizer as well as on feeding pipelines of steam boilers without economizers.

303. For hot water boilers water temperature measuring devices shall be installed at the water inlet and outlet.

The permissible hot water temperature shall be marked with a red line on the thermometer scale.

For boilers with the heating capacity exceeding 4,19 GJ/h (1 Gcal/h) the temperature measuring device at the boiler outlet shall be a recording one.

304. In case boilers are operated with liquid fuel a thermometer for fuel temperature measurement upstream of the atomizers shall be installed on the fuel pipeline in the nearest vicinity of the boiler.

Remote control of this temperature with installation of the secondary instrument on the boiler control panel is permitted.

305. Wall temperature measuring devices shall be provided for the boiler components (drums, tube sheets) in order to monitor metal temperature and prevent its increase above the permissible values in the course of the boiler start-up, shutdown and load following modes. The necessity for installation of these devices, their number and location shall be defined by the boiler developing organization.

Shutoff and control valves

306. Valves installed on the boiler or its pipelines shall have clear labelling on their casings with indication of the following:

1) name or trademark of the manufacturing organization;

2) nominal size;

3) nominal medium pressure and temperature (working pressure and permissible temperature may be indicated);

4) medium flow direction (in case of any design necessity).

The working pressure may be indicated instead of the nominal one in case valves are manufactured in accordance with special technical specifications.

307. Compliance of the valves with the nominal size of 50 mm and more with the requirements of the design and engineering documentation shall be confirmed by the manufacturing organization certificate which should include the data on chemical composition, mechanical properties of metal as well as heat treatment regimes and non-destructive control (in case these were prescribed by the technical specifications). The above-mentioned data shall refer to the main parts of the valve (casing, cover, stem, gate and fasteners).

308. Hand-wheels of valves shall be painted with red, and direction of rotation for the valve opening and closing shall be indicated on them.

309. Type, quantity and places for installation of valves shall be selected by the boiler developing organization in order to provide reliable isolation of the boiler and its components as per the design and engineering documentation.

The main shutoff device shall be installed at the boiler outlet upstream of its connection to the steam receiver of the boiler house. For power units it is permitted not to install shutoff devices at the boiler outlet unless their necessity is determined by the start-up and shutdown pattern.

310. For power units it is permitted not to install a shutoff device upstream of the boiler subject to installation of a shutoff device downstream of the high pressure heater and its bypass.

311. A check valve preventing water discharge from the boiler and a shutoff device shall be installed at the boiler feedwater inlet. In case the boiler is equipped with the economizer not isolated along the water supply line the check valve and the shutoff device shall be installed upstream of the economizer. For the economizer isolated along the water supply line the check valve and the shutoff device shall be also installed downstream of the economizer.

312. For hot water boilers the shutoff device shall be installed at the water inlet and outlet.

313. In boilers with the pressure exceeding 0,8 MPa at least two shutoff devices or a shutoff and a control device shall be installed on each blowdown and drainage pipeline as well as on the water (steam) sampling pipeline.  Throttle orifices may be also installed on the above-mentioned pipelines for boilers with the pressure exceeding 10 MPa. One shutoff device may be installed for blowdown of superheater chambers. The nominal size of the blowdown pipelines and any valves installed on them shall be at least 20 mm for boilers with the pressure below 14 MPa and at least 10 mm for boilers with the pressure of 14 MPa and more.

314. In case the medium is discharged from the boiler to a collection tank (separator, expander) with the pressure below the pressure in the boiler the collection tank shall be protected against overpressure above the design value.

The protection method as well as number and places for installation of valves, instrumentation and safety devices shall be selected by the boiler developing organization.

315. Valves on all pipelines of boilers, superheaters and economizers shall be connected by butt welding or through the use of flanges. For boilers with the steam capacity not exceeding 1 t/h threaded connections of valves are permitted with the nominal size of not more than 25 mm and the saturated steam pressure of not more than 0.8 MPa.

316. Valves shall be located as close to the boiler as possible with due regard for their  convenient operation.

Main steam isolation devices of steam boilers with the steam capacity exceeding 4 t/h shall be equipped with remote actuators with control output to the boiler operator's workplace (the control room shall be considered as the boiler operator's workplace subject to availability of the central control panel and in absence thereof - the boiler front).

317. Control valves shall be installed on the feeding lines of each boiler.

In case of automatic boiler feeding adjustment a remote actuator shall be provided to operate the feeding control valves from the boiler operator's workplace.

318. It is permitted not to install control valves on the feeding lines of steam boilers with the steam capacity of 2,5 t/h and less in case of automatic positional control of water level by the pump switching on/off.

319. If several feeding pumps with common suction and discharge pipelines are installed each pump shall have shutoff devices on the suction side and on the pressure side. A check valve shall be installed on the pressure side of each centrifugal pump upstream of the shutoff device.

Safety devices

320. Safety devices ensuring timely and reliable automatic shutdown of the boiler or its components in case of any unacceptable deviations from the prescribed operation conditions shall be provided for each boiler.

321. Steam boilers with in-chamber fuel combustion shall be equipped with automatic devices to cut off fuel supply to the burners in case of water level drop below the permissible value and for direct-flow boilers - in case of water flow increase above the permissible value.

For boilers with fuel-bed firing automatic devices shall switch off the draft systems and fuel supply mechanisms of the furnace in the above-mentioned cases.

322. Hot water boilers with multiple circulation and in-chamber fuel combustion shall be equipped with the devices automatically cutting off fuel supply to the burners and boilers with fuel-bed firing - with the devices switching off draft systems in case of water pressure reduction in the system up to the value when the risk of hydraulic shocks arises and in case of water temperature increase above the established limit.

323. Hot water boilers with in-chamber fuel combustion shall be equipped with automatic devices cutting off fuel supply to the boiler furnace and boilers with fuel-bed firing shall be equipped with automatic devices switching off the draft systems and fuel supply mechanisms of the furnace in the following cases:

1) water pressure increase in the outlet header of the boiler by more than 5% of the design or permitted value;

2) water pressure drop in the outlet header of the boiler up to the value corresponding to the saturation pressure with the maximum water temperature at the boiler outlet;

3) water temperature increase at the boiler outlet to the value specified by the manufacturing organization in the installation and operation manual; in the absence of such specification this temperature shall be assumed to be 20 °C below the saturation temperature under the working pressure in the outlet header;

4) water flow reduction in the boiler to the minimum permissible values determined by the manufacturing organization or in accordance with the following formula is these values are not specified by the manufacturing organization:

, kg/h,

where:

G_min is the minimum permissible water flow in the boiler, kg/h;

Q_max is the maximum heating capacity of the boiler, MW (kcal/h);

t_s is the water boiling temperature under the assumed working pressure at the boiler outlet, °C;

h is the water temperature at the boiler inlet, °C;

c is specific heat capacitance, kJ/kg·°C (kcal/kg·°C).

324. Automatic sound and light alarms of the upper and lower water level limits shall be installed on the boilers.

A similar alarm system shall be arranged for all parameters used for the automatic safety controls (safety devices) actuation to shut the boiler down.

325. Steam and hot water boilers with in-chamber fuel combustion shall be equipped with automatic devices cutting off fuel supply to the furnace in the following cases:

1) flame failure in the furnace;

2) switch-off of all exhausters;

3) switch-off of all blower fans.

326. Boilers with burners equipped with individual fans shall have protection to cut off fuel supply to the burner in case of the fan shutdown.

327. The necessity for installation of any additional safety devices on the boilers shall be defined by the boiler developing organization.

328. A water heating boiler operating with liquid or gaseous fuel shall be equipped with automatic devices cutting off fuel supply to the furnace in case water circulation in the boiler is stopped.

329. Safety devices shall be protected against any actions (switch-off, changes of settings) of the persons not related to their maintenance and repair and shall have the means for their operability verification.

330. Steam boilers shall be equipped with automatic feed control units regardless of their type and steam capacity. This requirement shall not be applied to water heating boilers with external steam extraction (apart from the boiler) not exceeding 2 t/h.

331. Steam boilers with the steam temperature at the main or intermediate superheater outlet exceeding 400 °C shall be equipped with automatic steam temperature control devices.

Feeding devices

332. Feeding of boilers may be collective with a common feeding pipeline for all connected boilers or individual for one boiler only.

Connection of boilers to the same feeding group is permitted provided that difference between working pressure values in different boilers shall not exceed 15%.

Feeding pumps connected to the common main pipeline shall have characteristics enabling parallel operation of the pumps.

333. The following equipment may be used for supply of feedwater to boilers:

1) power-driven centrifugal and piston pumps;

2) steam-driven centrifugal and piston pumps;

3) steam injectors;

4) hand-operated pumps;

5) water supply system.

The water supply system may be used only as the back-up boiler feeding source provided that the minimum water pressure in the water supply line upstream of the boiler feed control device exceeds the design or permitted pressure in the boiler by at least 0,15 MPa.

A steam-jet injector shall be treated as a steam-driven pump.

334. A nameplate with indication of the following data shall be attached to the casing of each feeding pump or injector:

1) name or trademark of the manufacturing organization;

2) serial number;

3) rated feed at the nominal water temperature;

4) number of revolutions per minute for centrifugal pumps or number of strokes per minute for piston pumps;

5) nominal water temperature upstream of the pump;

6) maximum discharge at the rated feed.

Subsequent to each major repair the pump shall be tested in order to determine its feed and discharge. Testing results shall be registered in the report which is to be filed in the boiler certificate.

335. Discharge generated by the pump shall ensure water feeding to the boiler at the working pressure downstream of the boiler with due regard for hydrostatic head and pressure losses in the boiler circuit, control devices and feedwater circuit.

The pump shall also provide for prevention of any boiler feeding interruptions upon actuation of safety valves with due regard for the maximum pressure increase in case of their complete opening.

In case of collective feeding of boilers the pump discharge shall be selected with due regard for the above-mentioned requirements as well as on the basis of feeding assurance for the boiler with the highest working pressure or the highest pressure losses in the feeding pipeline.

336. Feed rate of the feeding devices shall be determined on the basis of the nominal steam capacity of boilers taking into account the water flow for continuous or periodic blowdown, steam cooling, reducing and cooling and cooling devices and also with due regard for possible water or steam losses.

337. Type, characteristics, number and connection diagram for the feeding devices shall be selected by the boiler house developing organization in order to provide reliable and safe operation of the boiler in all modes including emergency shutdown. Operation of boilers with the steam capacity not exceeding 1 t/h with one feeding pump and an electric drive is permitted provided that the boilers are equipped with automatic safety controls eliminating the possibility for water level drop and pressure increase above the permissible value.

338. A safety valve shall be installed on the feeding pipeline between the shutoff device and the piston pump without any safety valves and with the generated discharge exceeding the design pressure in the pipeline.

VI. Boiler rooms

General

339. Stationary boilers shall be installed in buildings and rooms complying with the requirements of construction standards and rules.

Outdoor installation of boilers is permitted provided that the boiler is designed for operation under the specified climatic conditions.

340. Arrangement of rooms and attic floors above the boilers is not permitted. This requirement shall not be applicable to boilers installed in production rooms according to par. 342 of these Rules.

341. The following boilers may be installed in production rooms:

1) direct-flow boilers with the steam capacity of not more than 4 t/h each;

2) boilers complying with the condition (t - 100) · V  100 (for each boiler) where t is the saturated steam temperature at the working pressure, °C, and V is the water volume of the boiler, m³;

3) drumless hot water boilers with the heating capacity of not more than 10,5 GJ/h (2.5 Gcal/h) each;

4) waste heat boilers - without any limitations.

342. The place for installation of boilers inside the production rooms shall be separated from the rest of the room with fire-resistant partitions (with arrangement of doors in them) along the entire height of the boiler but not lower than 2 m.

Location of exits and door opening directions shall be defined by the design organization on the basis of the local conditions.

Waste heat boilers may be separated from the rest of the production room together with any furnaces or plants connected to them for the production process.

343. Arrangement of any utility and service rooms not intended for the boiler house personnel as well as any workshops not intended for repair of the boiler house equipment in the boiler house buildings is prohibited.

344. The lower storey floor level of the boiler room shall not be below the grade elevation of the area adjacent to the boiler house building.

No sumps shall be arranged in boiler houses. Sumps may be arranged in individual cases justified by the engineering necessity and according to the decision of the design organization for installation of shot-blasting equipment, heating mains entry and output units.

345. Exit doors from the boiler room shall be opened outwards. Doors from utility, service and also auxiliary production rooms to the boiler house shall be equipped with springs and opened towards the boiler house.

Lighting

346. The boiler house rooms shall have sufficient natural lighting and electric lighting in the night time.

Areas where natural lighting cannot be provided due to technical reasons shall have electric lighting. Illumination shall comply with the requirements of construction standards and rules set for natural and artificial lighting.

347. Boiler houses shall be equipped with emergency electric lighting. The following facilities shall be subject to mandatory arrangement of emergency lighting:

1) front of boilers and passages between boilers, behind and above boilers;

2) control boards and panels;

3) water level indicators and measuring devices;

4) ash chambers;

5) fan platforms;

6) exhauster platforms;

7) rooms for tanks and deaerators;

8) water treatment equipment;

9) platforms and ladders of boilers;

10) pump rooms.

348. Working and emergency electrical equipment and grounding thereof shall comply with the requirements of the regulations on electrical installations effective in the operating organization.

Location of boilers and auxiliary equipment

349. The distance between the boiler front or protruding sections of furnaces and the opposite boiler house wall shall be at least 3 m. For boilers operating with gaseous or liquid fuel the distance from the protruding sections of burner units to the boiler room wall shall be at least 1 m, and for the boilers with mechanized furnaces the distance from the protruding sections of furnaces shall be at least 2 m.

For boilers with the steam capacity not exceeding 2.5 t/h the distance from the boiler front or protruding sections of furnaces to the boiler house wall may be reduced to 2 m in the following cases:

1) if the furnace with hand feeding of solid fuel is operated from the front and its length does not exceed 1 m;

2) in the absence of any necessity for the furnace maintenance from the front;

3) if boilers are operated with gaseous or liquid fuel (provided that the distance from burner units to the boiler house wall is at least 1 m).

350. The distance between the boiler fronts and the protruding sections of furnaces located opposite each other shall be:

1) for boilers with mechanized furnaces - at least 4 m;

2) for boilers operated with gaseous or liquid fuel - at least 4 m, the distance between burner units shall be at least 2 m;

3) for boilers with hand feeding of solid fuel - at least 5 m.

351. Auxiliary boiler equipment and control panels may be installed in front of boilers. Width of free passages along the front shall be at least 1,5 m and any installed equipment shall not impede maintenance of boilers.

352. For boilers requiring side maintenance of the furnace or the boiler (stirring, air purging, cleaning of gas ducts, drums and headers, removal of economizer and superheater bundles, removal of tubes, maintenance of burner units, benchmarks and furnace components, maintenance of the regular blowdown system) width of the side passage shall be sufficient for maintenance and repair but not less than 1.5 m for boilers with the steam capacity of up to 4 t/h and at least 2 m for boilers with the steam capacity of 4 t/h and more.

353. In case no side maintenance of furnaces and boilers is required passages shall be provided between the outer boilers and the boiler house walls. Width of the above-mentioned passages as well as width of the passage between boilers and the rear wall of the boiler room shall be at least 1 m.

Width of the passage between individual boiler parts protruding from the lining (frames, pipes, separators) as well as between the above-mentioned parts and projecting elements of the building (brackets, columns, staircases, service platforms) shall be at least 0,7 m.

354. Passages in the boiler house shall have free height of at least 2 m.

In case there is no need to pass over the drum, steam dome or economizer the distance from them to the bottom structural elements of the boiler house flooring shall be at least 0,7 m.

355. Installation of any equipment not related directly to maintenance and repair of boilers or to the steam and (or) hot water production technology in the same room with boilers and economizers is prohibited.

Boilers and turbine units of power plants may be installed in a common room or in adjacent rooms without arrangement of any partition walls between the boiler house and the turbine hall.

Platforms and staircases

356. Permanent platforms and staircases with rails at least 0.9 m high and continuous downside sheeting of at least 100 mm shall be arranged for convenient and safe maintenance of boilers.

Gangways and staircases shall have rails on both sides. Platforms with the length exceeding 5 m shall have at least two staircases at the opposite ends.

357. Platforms and staircase steps may be made of:

1) expanded steel sheets;

2) corrugated steel sheets or sheets with uneven surface obtained by pad welding or any other technique;

3) honeycomb or strip (edge-wise) steel with the mesh area not exceeding 12 cm².

Usage of smooth platforms and staircase steps as well as their manufacturing of steel bars is prohibited.

Platforms and staircase steps in semi-open and open boiler houses shall be made of expanded steel sheets, honeycomb or strip steel.

358. Staircases shall be at least 600 mm wide, the height between the steps shall not exceed 200 mm and width of the steps shall be at least 80 mm. High staircases shall have interim platforms. Distance between the platforms shall not exceed 4 m.

Staircases with the height exceeding 1.5 m shall have the angle of inclination in relation to the horizontal axis not exceeding 50°.

359. Free passage width for the platforms shall be at least 600 mm and for maintenance of valves, instrumentation and other equipment - at least 800 mm.

Free height above the floor of platforms and staircase steps in the boiler house shall be at least 2 m.

360. Vertical distance from the maintenance platform of water level indicators to the water glass center shall be at least 1 m and not more than 1.5 m.

361. If the distance from the zero elevation of the boiler house to the top platform of boilers exceeds 20 m cargo and passenger elevators shall be installed. Number of elevators installed in the boiler room shall comply with the process design standards for thermal power plants.

Fuel supply and slag and ash removal

362. For boilers with the steam capacity of 2.5 t/h and more operated with solid fuel fuel supply to the boiler house and the boiler furnace shall be mechanized and removal of ash and slag shall be mechanized in boiler houses with the total slag and ash yield of 150 kg/h and more from all boilers regardless of their capacity.

363. In case of manual ash removal slag and ash pits shall be equipped with devices for watering of ash and slag in the pits or trolleys. In this latter case isolated chambers shall be arranged under the pit for installation of trolleys prior to discharge of ash and slag. Chambers shall have tight doors with glazed inspection windows and shall be equipped with ventilation and lighting systems.

Control of the pit gate and slag watering shall be arranged outside the chamber in any place safe for maintenance.

The free passage height along the entire path of the trolley shall be at least 2 m and side gaps - at least 0.7 m.

364. In case ash and slag is drawn off the furnace directly onto the service platform exhaust ventilation shall be arranged in the boiler room above the area for ash residue draw-off and watering.

365. Feeding hoppers with covers and drop bottoms shall be arranged for wooden fuel or peat in hand-fed shaft-type furnaces.

366. For liquid fuel combustion pads with sand shall be installed under the atomizers in order to prevent fuel spillage on the boiler house floor.

VII. Water chemistry regime

General requirements

367. Water chemistry regime shall assure operation of the boiler and the feeding line without any damage of their components due to scale and sludge deposition, increase of relative boiler alkalinity to dangerous limits or corrosion of metal.

All steam boilers with natural and multiple forced circulation and the steam capacity of 0,7 t/h and more, all direct-flow steam boilers regardless of their steam capacity and also all hot water boilers shall be equipped with pre-boiler water treatment plants. Any other efficient water treatment techniques ensuring compliance with the requirements of this paragraph may be also applied.

368. Water treatment technique for feeding of boilers shall be selected by the design organization.

369. For boilers with the steam capacity below 0.7 t/h the period between cleanings shall be such that the thickness of depositions at the most heat-stressed areas of the boiler heating surface by its shutdown for cleaning would not exceed 0.5 mm.

370. Makeup of boilers equipped with pre-boiler water treatment devices with raw water is not permitted.

In case makeup of the boiler with raw water under emergency conditions is provided in the design and engineering documentation two shutoff devices and a test cock between them shall be installed on each war water supply line connected to the softened makeup water or condensate lines as well as to feed tanks. Under the normal operation conditions the shutoff devices shall be closed and sealed and the test cock shall be opened.

Each case of the boiler makeup with raw water shall be registered in the water treatment (water chemistry) log sheet with indication of the makeup duration and feedwater quality within this period.

371. For steam and hot water boilers organizations engaged in adjustment of this equipment shall develop manuals and process flow diagrams with due regard for the requirements of these Rules, instructions of the manufacturing organizations, standard operating procedures, methodological guidelines for surveillance over water chemistry regime of steam and hot water boilers, methodological guidelines for development of manuals and process flow diagrams for operation of pre-boiler water treatment plants and maintenance of water chemistry regime for steam and hot water boilers.

Operation manuals for pre-boiler water treatment plants shall be developed by the plant manufacturing organizations.

372. Manuals and process flow diagrams shall be approved by the operating organization director and shall be available at the workplaces of the personnel.

Requirements for feedwater quality

373. Feedwater quality parameters for the boilers with natural and multiple forced circulation and the steam capacity of 0,7 t/h and more shall not exceed the values specified:

1) for steam gas-tube boilers - in Table 3 of these Rules;

2) for water-tube boilers with natural circulation (including water heating boilers) and the  working steam pressure of up to 4 MPa - in Table 4 of these Rules;

3) for water-tube boilers with natural circulation and the working steam pressure of 10 MPa - in Table 5 of these Rules;

4) for industry power boilers and waste heat boilers with the working steam pressure of up to 5 MPa - in Table 6 of these Rules;

5) for industry power boilers and waste heat boilers with the working steam pressure of 11 MPa - in Table 7 of these Rules;

6) for high-pressure boilers of combined cycle plants - in Table 8 of these Rules.

Table 3

Feedwater quality standards for steam gas-tube boilers

--------------------------------

<*> For boilers without economizers and boilers with cast-iron economizers dissolved oxygen content of 100 µg/kg and more is permitted.

Table 4

Feedwater quality standards for water-tube boilers

with natural circulation and the working steam pressure of

up to 4 MPa

--------------------------------

<*> Values for boilers operated with liquid fuel are always specified in the numerator and for boilers operated with any other types of fuel - in the denominator.

<**> For boilers without economizers and boilers with cast-iron economizers dissolved oxygen content of 100 µg/kg and more is permitted in the course of any fuel type combustion.

<***> The pH value may be reduced to 7.0 in individual cases substantiated by the design organization.

Table 5

Feedwater quality standards for water-tube boilers

with natural circulation and the working steam pressure of 10 MPa

--------------------------------

<*> In case of steam and condensate makeup with demineralized water the pH value may be increased to 10.5.

Note. For vertical gas-tube waste heat boilers with the working steam pressure exceeding 0,9 MPa as well as for soda recovery boilers feedwater quality parameters shall be regulated in accordance with the values specified in the last column of Table 6. Besides salt content in the feedwater shall be regulated for soda recovery boilers and shall not exceed 50 mg/kg.

Table 6

Feedwater quality standards for steam

industry power boilers and waste heat boilers

with the working steam pressure of up to 5 MPa

--------------------------------

<*> The value for water-tube boilers is always given in the numerator and the value for gas-tube boilers - in the denominator.

<**>  Hardness shall not exceed 15 µgEq/kg for water-tube boilers with the working pressure of 1.8 MPa.

<***> Iron compounds content may be increased to 100 µg/kg subject to application of chemical water treatment techniques reducing intensity of scale formation due to conversion of iron compounds into solution; in this case any standards for the permitted quantity of depositions inside steam generating pipes approved by the operating organization shall be complied with. Conclusion on the possibility for above-mentioned increase of iron compounds content in the feedwater shall be made by the design organization.

<****> The upper pH limit shall be established not to exceed 9.5 depending on the materials used in the steam and condensate circuit equipment.

Table 7

Feedwater quality standards for industry power

boilers and waste heat boilers with the working steam pressure of

11 MPa

--------------------------------

<*> The upper pH limit shall be established not to exceed 9.5 depending on the materials used in the steam and condensate circuit equipment.

<**> The nominal salt content shall be determined with a conductometric salinity meter with prior degassing and concentrating of the sample and specific electric conductivity shall be measured with a conductivity meter with prior hydrogen ion polishing of the sample; one of the above-mentioned parameters shall be controlled.

Table 8

Feedwater quality standards for high-pressure boilers

of combined cycle plants

--------------------------------

<*> In case the steam generator is operated with natural gas iron content standards may be exceeded by 50%.

<**> The nominal salt content shall be determined with a conductometric salinity meter with prior degassing and concentrating of the sample and specific electric conductivity shall be measured with a conductivity meter with prior hydrogen ion polishing of the sample; one of the above-mentioned parameters shall be controlled.

374. Feedwater quality parameters for water-tube boilers with natural circulation and the working steam pressure of 14 MPa and all direct-flow power boilers shall not exceed the values specified:

1) for water-tube boilers with natural circulation and the working steam pressure of 14 MPa - in Table 9 of these Rules;

2) for direct-flow power boilers - in Table 10 of these Rules.

Table 9

Feedwater quality standards for water-tube boilers

with natural circulation and the working steam pressure of 14 MPa

--------------------------------

Notes.

In case of steam and condensate makeup with demineralized water the pH value may be increased to 10.5.

Sodium compounds content for boilers with the pressure of 14 MPa shall not exceed 50 µg/dm³. Standards for sodium content in the feedwater at CHP plants with industrial steam extraction may be adjusted in case of no gas-tight or any other boilers with increased local thermal loads on the heat screens are installed on such plants and steam superheating is controlled by the condensing attemperator system.

Cation conductivity for boilers with the pressure of 14 MPa shall not exceed 1.5 µOhm/cm. Relevant adjustment of the standard for specific electric conductivity shall be permitted in case of any adjustment of the sodium content norms for feedwater.

Hydrazine content (in case of water treatment with hydrazine) shall be 20 to 60 µg/dm³; hydrazine content of up to 3000 µg/dm³ shall be permitted in the course of the boiler startup and shutdown (with steam release into the atmosphere).

Content of ammonia and its compounds shall not exceed 1000 µg/dm³; ammonia content increase up to the values ensuring maintenance of the required steam pH but not resulting in any exceedance of the copper compounds content limits in feedwater shall be permitted in individual cases approved by the regional power grid control department (for the equipment controlled (supervised) by the control operator).

Free sulfite content (in case of sulfitation) shall not exceed 2 mg/dm³.

Aggregate content of nitrites and nitrates for boilers with the pressure of 14 MPa shall not exceed 20 µg/dm³.

Table 10

Feedwater quality standards for direct-flow

power boilers

--------------------------------

<*> In case all heat exchangers installed in the condensate feeding circuit have tubes made of stainless steel or any other corrosion-resistant materials - not exceeding 2 µg/dm³.

Notes.

For power plants with direct-flow boilers and steam pressure of 14 MPa where the design does not provide for purification of all condensate discharged from the turbine condensate tank sodium compounds content in the feedwater and steam not exceeding 10 µg/dm³ is permitted during operation of boilers; total feedwater hardness shall not exceed 0.5 µgEq/dm³  and iron compounds content shall not exceed 20 µg/dm³.

Feedwater, steam and turbine condensate quality standards for direct-flow boilers with the pressure of 10 MPa in the course of operation shall be established by the power utility systems based on the existing operation experience.

375. Makeup and delivery water quality for hot water boilers shall comply with the requirements specified in Table 11 of these Rules.

Table 11

Makeup and delivery water quality standards for

hot water boilers

--------------------------------

<*> The value for boilers operated with solid fuel is specified in the numerator and for boilers operated with liquid and gaseous fuel - in the denominator.

Requirements for boiler water quality

376. Boiler water quality standards, the required regime for its corrective treatment, continuous and periodic blowdown modes shall be determined on the basis of the boiler manufacturing organization guidelines, standard operating procedures for water chemistry regime maintenance or on the basis of the thermal and chemical testing results.

For steam boilers with the pressure of up to 4 MPa inclusive having riveted joints the relative boiler alkalinity shall not exceed 20%. For boilers with welded drums and connection of pipes by expanding (or expanding with sealing back-welding) the relative boiler alkalinity may reach 50%. For boilers with welded drums and welded pipes the relative boiler alkalinity is not regulated.

For steam boilers with the pressure exceeding 4 MPa and up to 10 MPa inclusive the relative boiler alkalinity shall not exceed 50%; for boilers with the pressure exceeding 10 MPa and up to 14 MPa inclusive - 30%.

VIII. Technical examination and commissioning

Technical examination

377. Boilers covered by these Rules shall be subject to technical examination prior to putting into operation, regularly in the course of operation and also to unscheduled examination in case of necessity.

Technical examination shall include checks of the documentation, interior and exterior inspection of the boiler and its components (particularly frame metalwork if any) at the accessible areas, hydraulic testing and registration of the examination results.

378. Technical examination of boilers shall be performed by the commission appointed by the order or instruction of the operating organization management.

The commission shall consist of the following members:

1) the operating organization worker appointed by the organization order to perform surveillance (control) over technical conditions and operation of the boilers (hereinafter - the surveillance (control) person) - head of the commission;

2) the person responsible for operability and safe operation of this particular boiler;

3) other workers of the operating organization as well as workers of the expert organization and any other organizations (in case of necessity).

Examination of superheaters and economizers constituting the same unit with the boiler shall be performed concurrently with the boiler examination.

379. The boiler shall be shut down not later than the examination date specified in its certificate. The operating organization shall inform the commission on the upcoming boiler examination not later than 5 days prior to the examination date.

In case it is impossible to present the boiler for technical examination within the scheduled time limits due to production conditions the operating organization shall present it ahead of schedule.

380. The commission shall perform technical examination within the following time limits:

1) exterior and interior inspection - at least once per 4 years;

2) hydraulic testing - at least once per 8 years.

Hydraulic testing of boilers shall be carried out only in case of satisfactory results of exterior and interior inspection.

381. The date of the next scheduled technical examination of the boiler shall be defined by the operating organization administration in coordination with the commission. In case of necessity to engage any specialists from external organizations the operating organization shall inform them on the technical examination date in advance. Operation of the boiler shall be stopped not later than the scheduled technical examination date specified in its certificate.

The operating organization administration shall be responsible for timely and proper preparation of the boiler for technical examination.

382. The boiler developing organization shall develop the inspection sequence, technical condition checking for the boiler components inaccessible for exterior and interior inspection, special-purpose methods (rejection standards) and boiler inspection frequency for each series of boilers and specify this information in the design and engineering documentation. Based on this information the manufacturing organization shall develop the boiler installation and operation manual reflecting and particularizing all above-mentioned data and supply it together with the boiler. In case the boiler installation and operation manual does not contain any sections on technical examination the operating organization of the nuclear facility may develop the technical examination guidelines for the boiler in coordination with the boiler manufacturing organization.

All non-destructive control methods including the acoustic emission method may be used in the course of examination.

Technical examination of any boilers inaccessible (or accessible to the limited extent) for regular control due to their design peculiarities, radiation situation or any other reasons shall be performed through the use of remote devices and non-destructive methods for control of metal and weld joints.

In each particular case the manufacturing organization shall specify the method, rejection standards, frequency and scope of control providing timely detection and elimination of defects in the installation and operation manual.

383. Exterior and interior inspection shall be performed in order:

1) to check that the boiler is installed and equipped in accordance with these Rules, design and documentation for the boiler and that the boiler and its components do not have any damages (in the course of original examination);

2) to confirm operability of the boiler and possibility for its further operation (in the course of scheduled and unscheduled examinations).

384. In the course of exterior and interior inspection of the boiler attention shall be paid to detect any possible cracks, tears, buckles, bulges and corrosion on the inner and outer surface of walls, signs of steaming and gaps in weld, riveted and expanded joints as well as any lining damages capable of causing the risk of the boiler component metal overheating.

385. Installed power and hot water boilers may be lined prior to presentation for technical examination provided that all erection units shall be inspected carefully before application of the lining. The commission including representatives of the boiler operating personnel, the metal research laboratory (service) of the operating organization and the installation organization shall be established for this purpose.

Adherence to the allowances for mutual alignment of parts and assembly units, displacement of edges and tilt of the mated pipes, structural elements of weld joints, presence of factory labelling on the boiler components and its compliance with the certificate data, absence of any damage of parts and assembly units during transportation shall be checked in the course of inspection.

Subsequent to positive results of inspection and check of compliance of the performed control of weld joints (both manufacturing and installation ones) with the requirements of these Rules the commission shall issue a report for each erection unit which shall be approved by the chief engineer of the operating organization. The report shall be an integral part of the boiler installation quality certificate and the basis for arrangement of the lining prior to technical examination of the boiler.

The completely assembled boiler shall be presented to the commission for interior inspection (at the accessible areas) and hydraulic testing.

In case any lining damages are detected in the course of the boiler inspection giving grounds for suspicions that the units have been affected by impacts during installation the lining shall be partially opened in order to check the condition of tubes and to eliminate any damages.

386. Boilers subjected to interior inspection and hydraulic testing in the manufacturing organization and delivered to the installation site in the assembled condition shall be subject to original technical examination at the place of installation performed by the surveillance (control) person together with the person responsible for their operability and safe operation.

387. Technical conditions of the boiler components inaccessible for interior and exterior inspection shall be checked in accordance with the installation and operation manual provided by the manufacturing organization where the control scope, methods and frequency shall be stated.

388. The operating organization shall carry out exterior and interior inspection subsequent to each cleaning of inner surfaces or repair of the components but at least once per 12 months and also prior to the boiler presentation for technical examination. The person responsible for operability and safe operation of the boiler shall ensure elimination of all detected defects prior to the boiler presentation for examination.

Interior inspections of boilers at nuclear facilities may be performed during the period of their overhaul repair but at least once per 4 years.

389. In case of any unscheduled technical examination the reason for such examination shall be stated. Unscheduled examination of boilers shall be performed in the following cases:

1) if the boiler has been out of operation for more than 12 months;

2) if the boiler has been dismantled and installed at a new place;

3) if any elimination of bulges or dents as well as repair with welding of the main boiler components (drum, header, flame tube, tube sheet, pipelines within the boiler, steam dome, dirty tank, combustion chamber) has been performed;

4) if more than 15% of the anchor ties on any wall have been replaced;

5) after replacement of the drum, header, heat screen, superheater, steam cooler or economizer;

6) if more than 50% of the total number of wall and boiling tubes or flue tubes or all superheater and economizer tubes have been replaced simultaneously;

7) upon request of the surveillance (control) person or the person responsible for operability and safe operation of the boiler.

390. Prior to exterior and interior inspection the boiler shall be cooled and cleaned thoroughly from any scale, soot, ash and slag depositions. The drum internals shall be removed in case they impede the inspection.

In case of any doubts with regard to good condition of the walls or joints the commission performing technical examination shall be entitled to demand complete or partial opening of the lining or removal of insulation or complete or partial dismantling of tubes in the course of interior inspection of a boiler with flue tubes.

391. In case any defects of the boiler decreasing the strength of its components particularly thinning of walls and wear of ties are detected in the course of examination further operation of the boiler with reduced parameters (pressure and temperature) prior to replacement of defective components may be permitted. The possibility to operate the boiler with reduced parameters shall be confirmed by strength calculations presented by the operating organization; in this case checking calculation of the flow capacity shall be performed for safety valves.

392. In case any mechanical tests of metal of the drum or any other main boiler components are carried out in the course of examination and subsequent to the testing results for any component made of carbon steel it is determined that the breaking point is below 320 MPa or the ratio between 0.2% proof stress and breaking point exceeds 0.75 or relative elongation is less than 14% or sharp-notch impact viscosity is below 25 J/cm² further operation of this component shall be prohibited till the opinion of the boiler developing organization and the main material research organization is obtained. The permissible values of the above-mentioned parameters for alloyed steels shall be established in each particular case by the manufacturing organization or the main material research organization.

393. In case any surface cracks or losses of integrity (leaks, signs of steaming, salt depositions) are detected in the course of the boiler examination at the expanded or riveted joints the defective joints shall be checked for absence of inter-crystalline corrosion prior to elimination of defects by re-caulking, back-welding or re-rolling. Sections affected by inter-crystalline corrosion shall be removed.

The procedure and scope of the above-mentioned studies shall be defined by the operating organization and the main material research organization.

394. In case it is defined by analysis of the defects revealed in the course of the boiler examination that their occurrence is related to the boiler operation mode in this organization or characteristic for this boiler design the commission performing the examination shall demand unscheduled examination of all boilers installed in this organization and operated under the same mode or all boilers of the same design respectively.

395. Results of all technical examinations of boilers and the opinion on the possibility for further operation of the boiler with indication of the permitted operating parameters and the next technical examination date shall be registered in the boiler certificate and signed by the commission members.

In case any additional testing and studies are carried out in the course of technical examination types and results of these tests and studies shall be recorded in the boiler certificate with indication of the sampling points or sections subjected to testing and also the reasons for additional testing.

The established date of the next technical examination shall not exceed the period specified in these Rules.

396. Boiler (frame) metalwork erected at the operation site shall be subject to original technical examination prior to the boiler commissioning, regular technical examination - in the course of operation and unscheduled technical examination. Technical examination results for the boiler metalwork shall be registered in the boiler certificate.

Technical examination shall be performed in accordance with the operation manual and the requirements of these Rules.

397. In case any defects are detected during technical examination of the boiler that cast any doubt about its strength or any defects with the cause which is difficult to define operation of this boiler shall be prohibited till the opinion of the operating organization and the boiler developing organization and (or) (the main material research organization) on the causes of the above-mentioned defects as well as on the possibility and conditions for further operation of the boiler is obtained.

398. Subsequent to the original technical examination of the boiler and prior to its commissioning the boiler shall be registered in the operating organization.

Boilers registered prior to entry of these Rules into force shall not be subject to re-registration.

Commissioning works

399. Commissioning works for the boiler equipment may be performed by specialized boiler adjusting organizations having all equipment and trained personnel necessary for proper performance of these works.

Prior to commissioning works and integrated testing the boiler shall be presented to the commission for original technical examination.

Commissioning works after the boiler repair or refurbishment (retrofitting) shall be performed by the operating organization.

400. Startup of the boiler for performance of commissioning works shall be arranged subsequent to its inspection by the operating organization in order to control:

1) availability and operability of the instrumentation, safety devices and alarms prescribed by the requirements of these Rules and the design and engineering documentation;

2) availability of the trained and certified operating personnel and specialists;

3) availability of all approved technical guidelines and the required operation documentation at the workplaces;

4) operability of feeding devices;

5) correctness of the boiler connection to the common steam pipeline as well as connection of the feeding, blowdown and drainage lines;

6) fuel supply equipment acceptance certificate;

7) assurance of the required feedwater quality.

401. Responsibilities for safe boiler maintenance in the course of commissioning works shall be defined by the joint order of the operating organization and the commissioning organization management.

402. Prior to putting the boiler into permanent operation it is necessary to do the following in the course of commissioning works:

1) test all devices including redundant ones;

2) check measuring devices;

3) set the automatic boiler control systems and perform dynamic tests;

4) adjust the control, interlocking and alarm systems;

5) adjust safety valves;

6) adjust the combustion regime;

7) adjust water chemistry regime of the boiler.

403. Upon completion of commissioning works integrated testing of the boiler and auxiliary equipment under the rated load shall be performed for 72 h.

Commencement and completion of integrated testing shall be defined by the order of the operating organization. Upon completion of integrated testing the certificate shall be issued to confirm the boiler acceptance for operation. The technical report on commissioning works with tables and instructions, graphs and other materials reflecting any determined and actually obtained data on adjustment and setting of the devices, descriptions and drawings of all modifications introduced at the adjustment stage shall be attached to the certificate.

Commissioning of boilers

404. The permit for commissioning of a newly installed boiler shall be given in accordance with these Rules in the form of an order of the operating organization based on the results of technical examination and inspection in the course of integrated testing.

405. The following aspects shall be controlled during checking of the boiler operation arrangement procedure:

1) availability and operability of valves, instrumentation and safety devices in accordance with the requirements of these Rules;

2) operability of feeding devices and their compliance with the design and engineering documentation and the requirements of these Rules;

3) compliance of the boiler water chemistry regime with the requirements of these Rules;

4) correctness of the boiler connection to the common steam pipeline as well as connection of the feeding, blowdown and drainage lines;

5) availability of certified operating personnel as well as engineering and technical specialists having passed verification of knowledge of these Rules and instructions;

6) availability of technical guidelines for the boiler house personnel, shift and repair log sheets;

7) compliance of the boiler room with the design and requirements of these Rules.

406. A plate with the size of at least 300x200 mm shall be attached to each commissioned boiler in a visible place with indication of the following data:

1) registration number;

2) permitted pressure;

3) date, month and year of the next technical examination.

407. The boiler may be put into operation subsequent to fulfillment of the requirements specified in par. 404 and 406 of these Rules.

IX. Operation

Arrangement of operation

408. Administration of the boiler owner organization shall ensure maintenance of the boilers in good operating conditions and their safe operation.

The operating organization shall:

1) define the positions (professions) of workers who may be admitted to operation of boilers and ensure the staffing level of the personnel engaged in boiler operation with due regard for the established requirements;

2) admit the persons complying with the qualification requirements and without any medical contra-indications for the relevant works to operation of steam and hot water boilers;

3) appoint a surveillance (control) person (or persons) from among the specialists checked for knowledge of these Rules (the number of surveillance (control) persons shall be defined on the basis of calculations of time required for timely and proper performance of duties assigned to these persons according to the job description);

4) appoint the required number of persons responsible for operability and safe operation of boilers from among the specialists having passed knowledge assessment;

5) develop and approve the guidelines for the person responsible for operability and safe operation of boilers in accordance with these Rules, boiler installation and operation manuals of the manufacturing organizations with due regard for the layout and local operating conditions for the boilers and any other equipment installed at the nuclear facility;

6) develop and approve the standard operating procedure for the boiler operating personnel in accordance with these Rules, boiler installation and operation manuals of the manufacturing organizations with due regard for the layout and local operating conditions for the boilers and any other equipment installed at the nuclear facility (this standard operating procedure shall be available at workplaces and submitted to the operating personnel against receipt);

7) provide pre-certification preparation and certification of specialists, training and knowledge assessment for the workers engaged in maintenance and safe operation of the boilers and their equipment;

8) organize and carry out in-process control of adherence to the requirements of these Rules and guidelines;

9) assure availability and functioning of the required instrumentation and boiler operation monitoring systems;

10) perform technical examinations and diagnostics of the boilers within the specified time limits;

11) prevent any entries of unauthorized persons to the rooms where boilers are installed;

12) implement all orders of Rostechnadzor officers;

13) implement measures for confinement and mitigation of consequences in case of any accidents with the boilers, assists the government authorities in investigation of the accident causes;

14) analyze the causes of accidents and incidents in the course of the boiler operation, implement measures for their elimination, keep records of accidents and incidents with the boilers;

15) inform Rostechnadzor as well as any other government authorities, the local government bodies and the public about any accidents with boilers in a timely manner;

16) submit any information on accidents and incidents, their causes and measures implemented to Rostechnadzor.

409. Clocks and a telephone for communication with the workers at the steam consuming facilities as well as with technical services and administration of the operating organization shall be provided in the boiler room.

For operation of waste heat boilers additional telephone communication between the workers at the waste heat boiler control panels and at heat sources shall be arranged.

410. Any third persons shall be admitted to the boiler house only with the permission of the operating organization administration and shall be accompanied by its representative.

411. The worker responsible for operability and safe operation of the boiler (or boilers) of the organization (shop or division) shall be appointed by an organizational/executive directive of the head of the boiler (boilers) operating organization managing the operating personnel. The number and date of the organizational/ executive directive on appointment of the person in charge shall be specified in the boiler certificates.

During vacations, business trips, sick leaves or in any other cases when the person in charge is absent performance of his/her duties shall be assigned by order to any other worker checked for knowledge of these Rules. In such cases no records shall be made in the boiler certificate.

Maintenance

412. Training and knowledge assessment for firemen and boiler house operators shall be carried out in training institutions as well as at special-purpose courses.

Training programs shall be developed on the basis of standard programs approved by the operating organization.

No individual personnel training is permitted.

413. Knowledge assessment for boiler operators shall be performed by the commission appointed by the order of the operating organization director. The knowledge assessment protocol shall be signed by the head of the commission and its members. Relevant certificates signed by the head of the commission shall be issued to the persons having passed knowledge assessment.

414. Regular assessment of the personnel knowledge shall be performed in accordance with the procedure established in the operating organization.

415. Unscheduled knowledge assessment shall be performed in the following cases:

1) off-the-job period exceeding 6 months;

2) transfer to servicing of the different boiler type;

3) boiler transfer to combustion of different fuel type;

4) installation of any new equipment on the boiler or refurbishment (retrofitting) of the equipment and process systems.

The commission for regular or unscheduled knowledge assessment shall be appointed by the organization order.

In case of any amendments to the boiler installation and operation manual the operating personnel shall be familiarized with these amendments with signed acknowledgment.

416. Results of the operating personnel knowledge assessment shall be registered in the protocol signed by the commission head and members with the relevant record in the certificate.

417. In case of any off-the-job period in the relevant field exceeding 12 months the operating personnel shall pass on-the-job training according to the program approved by the organization management in order to recover practical skills after knowledge assessment and before admittance to unsupervised work.

418. Admittance of the operating personnel to unsupervised operation of boilers shall be arranged by the nuclear facility-wide (shop- or division-wide) order (directive).

419. It is prohibited to leave the boiler without continuous attendance of the operating personnel both in the course of the boiler operation and after its shutdown till the pressure reduction to atmospheric one.

420. Operation of boilers without continuous attendance of the operating personnel is permitted subject to availability of automation devices, alarms and protections ensuring maintenance of the normal operation conditions, elimination of emergencies as well as shutdown of the boiler in case of any operational occurrences capable of causing the boiler damage.

Verification of instrumentation, automatic

protections, valves and feeding pumps

421. Operability verification for pressure gauges, safety valves, water level indicators and feeding pumps shall be performed in accordance with the procedure established in the operating organization within the following time limits:

1) for boilers with the working pressure of up to 1.4 MPa inclusive - at least once per shift;

2) for boilers with the working pressure exceeding 1.4 MPa and up to 4 MPa inclusive - at least once per day.

Verification results shall be registered in the shift log sheet.

422. Water level indicators shall be checked by blowdown. Operability of remote level indicators shall be checked by comparison of their readings with the readings of direct-action water level indicators.

423. The procedure and time limits for setting and operability verification of safety devices, feeding pumps, alarms and automatic protections depending on their design and the process conditions shall be specified in the installation and operation manuals for these devices developed and approved by the operating organization in accordance with the technical documentation for these devices provided by the manufacturing organizations.

424. Operability verification for redundant feeding pumps shall be performed by their short-term switching into operation in accordance with the schedules and guidelines approved by the operating organization administration.

425. Operability verification for pressure gauges shall be performed through the use of a three-way cock or any shutoff valves replacing it by setting of the gauge hand to zero.

Emergency shutdown of the boiler

426. The boiler shall be immediately shut down and switched off by actuation of automatic protections or by the operating personnel in any cases prescribed in the technical guidelines particularly in case of:

1) any safety valve malfunction;

2) pressure increase in the boiler drum by 10% above the permitted value;

3) water level reduction below the permissible value;

4) water level increase above the permissible value;

5) stoppage of all feeding pumps;

6) disabling of all direct-action water level indicators;

7) detection of any cracks, bulges, gaps in weld joints, ruptures of anchor bolts or ties in the main boiler components (drum, header, chamber, steam and water circulating tubes and downcomers, steam and feeding pipelines, flame tube, fire box, furnace shell, tube sheet, external separator, valves);

8) unacceptable pressure increase or drop in the direct-flow boiler circuit upstream of inbuilt gate valves;

9) flame failure in the furnace in case of in-chamber fuel combustion;

10) water flow reduction in a hot water boiler below the minimum permissible level;

11) water pressure drop in the hot water boiler circuit below the permissible value;

12) water temperature increase at the hot water boiler outlet to the value of 20 °C below the saturation temperature corresponding to the working water pressure in the water outlet header;

13) malfunction of automatic safety devices or emergency alarms including loss of voltage on these devices;

14) fire breakout in the boiler house.

427. The procedure for emergency shutdown of the boiler shall be specified in the technical guidelines effective in the operating organization. Causes of the emergency boiler shutdown shall be registered in the shift log sheet and promptly brought to the notice of the boiler house administration.

Repair and refurbishment (retrofitting) of boilers

428. The operating organization administration shall provide for timely repair of boilers in accordance with the approved preventive maintenance schedule. Repair and refurbishment (retrofitting) of boilers shall be performed in accordance with the technical specifications and technology developed prior to commencement of the works.

Repair and refurbishment (retrofitting) of boilers shall be performed in accordance with the requirements specified in Sections III-VII of these Rules (with regard to technical requirements).

Repair involving welding and expanding of the pressurized boiler components shall be performed by a specialized organization.

429. A repair log sheet shall be issued for each boiler where the person responsible for operability and safe operation of the boiler shall record the information on any performed repair works, materials used, welding and welding operators and shutdown of boilers for cleaning and flushing. Replacement of tubes and rivets, re-rolling of pipe connections to drums and headers shall be marked on the tube (rivet) arrangement diagram attached to the repair log sheet. Results of the boiler inspection prior to cleaning with indication of scale and sludge deposition thickness and all defects revealed within the repair period shall be also registered in the repair log sheet.

430. Information on repair of the boiler and its components shall be recorded in the repair log and specified in the boiler certificate.

431. Welding operators with licenses for performance of these welding works issued in accordance with the procedure established by the operating organization shall be admitted to perform welding works.

Welding operators may be admitted only to the types of welding works specified in their licenses.

432. The quality control system (incoming, in-process and acceptance control) assuring performance of the works in accordance with the requirements of these Rules shall be applied in the course of repair and refurbishment (retrofitting) of boilers.

433. Prior to commencement of any works inside the drum or header of the boiler connected with other operating boilers by pipelines particularly the steam pipeline, feeding, drainage, discharge lines as well as prior to interior inspection or repair of the pressurized components the boiler shall be isolated from all pipelines with plugs in case flanged valves are installed on them. In case non-flanged valves are installed on the steam and water pipelines the boiler shall be isolated by two shutoff devices with a drainage device between them with the nominal size of at least 32 mm connected to the atmosphere. Drives of gate valves as well as valves of open drains and the emergency water discharge line from the drum shall be locked. Keys of the locks shall be kept by the person responsible for operability and safe operation of the boiler unless any other procedure for their keeping is established at the nuclear facility.

434. Thickness of the plugs used for the boiler isolation shall be determined on the basis of strength calculations. The applied plugs shall be tested, registered and marked (with indication of the nominal pressure and diameter) and shall also have a protruding part (shank) in order to detect presence of the plug.

In case gaskets are installed between flanges and the plug these gaskets shall not have any shank parts.

435. Access of people inside the boiler as well as opening of shutoff valves after the people have left the boiler shall be performed only subject to the written permission (safety permit).

Extension of the specified lifetime of boilers

436. The specified lifetime of boilers may be extended based on the resolution of the operating organization approved by the boiler developing organization (or the manufacturing organization) and the main material research organization.

Technical examination results for the boiler including technical diagnostics results, the remaining lifetime assessment, reliability and strength calculations confirming the possibility to extend the specified boiler lifetime as well as any reports confirming the possibility for the boiler to perform its functions within the extended service life in compliance with all safety requirements, metal condition inspection reports and in-service metal inspection programs developed for the additional lifetime shall be attached to this resolution.

X. Requirements for gas-tube boilers

437. The requirements of this subsection shall be applied to steam and hot water gas-tube boilers with the steam capacity of up to 10 t/h and the power capacity of up to 10 MW, the working pressure of up to 1.6 MPa and the temperature of up to 200 °C.

Design

438. Design of a gas-tube boiler shall provide the possibility to inspect the inner surface of the boiler casing. In case it is impossible to inspect individual boiler components the procedure and scope of their technical condition monitoring shall be specified in the boiler installation and operation manual provided by the manufacturing organization.

439. Flat end plates shall have raised edges with the radius of at least 40 mm. Flat end plates without raised edges may be used in the design of boilers with the steam capacity not exceeding 1.5 t/h, the power capacity not exceeding 2 MW and the pressure of up to 1 MPa subject to accessibility of the weld joints between flat end plates and the boiler casing shell and the reversing chamber for visual control and non-destructive control.

Usage of flat end plates without raised edges in any other cases shall be approved by the developing organization.

440. Corner weld joints for welding of flat end plates shall be performed with double-side edge preparation and shall have smooth transition from the end plate to the shell.

441. The distance between the centers of adjacent flue tube apertures in flat end plates shall be at least equal to the aperture diameter plus 15 mm.

442. Inspection windows shall be provided in the rear wall of the end plate for each flame tube in order to monitor the combustion process; rupture protection devices shall be also installed.

It is permitted not to install rupture protection devices provided that the boiler is equipped with automatic safety controls.

443. Maximum dimensions of non-reinforced clearances for flat end plates and the reversing fire chamber shall be substantiated with strength calculations.

444. In order to compensate for thermal expansion difference between non-uniformly heated components in the boiler design the distance between the flame tube and the angle tie shall be at least 250 mm, between the flame tube and the casing shell - at least 200 mm and between the angle tie or anchor and flue tubes - at least 120 mm.

445. Checking fatigue strength calculation shall be performed for the entire boiler structure in order to assess the specified lifetime of the boiler and number of cold and hot start-ups.

446. A gap of at least 150 mm shall be provided between flue tubes in the central section of the boiler in order to inspect and clean the upper part of the flame tube and the reversing fire chamber.

447. Smooth flame tubes may be used in boilers with the casing length of less than 4 m and the working pressure of less than 0.9 MPa.

448. Wall thickness of flame tubes for the boilers operated with liquid and gaseous fuel shall not exceed 22 mm.

449. A smooth flame tube may be reinforced by stiffening rings with full penetration throughout the ring wall. Stiffening rings should not be installed in gas- and liquid-fueled furnaces in the maximum heat flux areas.

450. Height and number of the flame tube corrugated sections shall be selected depending on the thermal expansion difference compensation value for the heated components.

451. Inside the flame tube areas of the inlet aperture, burner fastening, weld joint between the flat end plate and the flame tube and sections with the length of at least 200 mm shall have insulation.

452. Anchor ties and corner gussets are used for reinforcement of flat end plates of the boiler casing and flat end plates of the reversing fire chamber and shall be located uniformly across the surface.

453. Wall thickness of the corner tie shall not exceed the shell thickness; it shall be made of the same material as the shell.

Weld joints between the corner gusset and the flat end plate and the shell shall be made with full penetration throughout the gusset wall thickness and shall have smooth transitions to basic metal.

Corner ties shall be located at the angle of at least 30° in relation to the longitudinal axis of the steam boiler.

Reinforcement of flat end plates with stiffening ribs is not permitted.

Automatic protection

454. Boilers shall be equipped with automatic protections stopping their operation upon exceedance of the parameters specified in the manuals of the manufacturing organizations in the following cases:

1) for steam boilers:

steam pressure increase;

water level decrease;

water level increase;

increase or drop of gaseous fuel pressure upstream of the burners;

drop of liquid fuel pressure upstream of the burners;

air pressure drop upstream of the burner;

reduced underpressure in the furnace;

burner flame failure;

loss of the boiler house power supply;

2) for hot water boilers:

water pressure increase or drop at the boiler outlet;

water temperature increase at the boiler outlet;

water flow reduction in the boiler;

increase or drop of gaseous fuel pressure upstream of the burners;

burner flame failure;

drop of liquid fuel pressure upstream of the burners;

reduced underpressure in the furnace;

air pressure drop upstream of the burners;

loss of the boiler house power supply.

Sound and light alarms shall be actuated automatically upon reaching the permissible limits of the boiler parameters.

Appendix 1

to federal rules and regulations

in the field of atomic energy use

"Rules for arrangement

and safe operation of steam

and hot water boilers for

nuclear facilities",

approved by Order of the Federal

Environmental,

Industrial and Nuclear Supervision Service

dated March 19, 2018 No. 113

TERMS AND DEFINITIONS

Water heater - delivery water heater, steam or water-water heat exchanger utilizing steam or boiler water heat for production of hot water with different parameters. A water heater may be built into the boiler or stand-alone.

Bend - a curved section of a bent elbow.

Burner (of a boiler) - device for injection of fuel and air necessary for combustion into the boiler furnace and assurance of stable fuel combustion.

Elbow - a shaped part of a pipeline intended for angle-wise change of the working medium flow direction.

Bent elbow - elbow bent through the use of a special-purpose equipment or device.

Water heating boiler - a steam boiler with the water heating device installed inside the drum for heating of water used outside the boiler itself as well as a steam boiler with a stand-alone water heater integrated into its natural circulation.

Note. The requirements of these Rules shall be applied to the water heater irrespective of whether it can be isolated from the boiler with valves or not.

Hot water boiler - device with a furnace heated with products of fuel combustion in it and intended for heating of water under pressure above the atmospheric one which is used as heat transfer medium outside the device itself.

Steam boiler - device with a furnace heated with products of fuel combustion in it and intended for production of steam with the pressure above the atmospheric one to be used outside the device itself.

Stationary boiler - a boiler installed on a fixed foundation.

Waste heat boiler - steam or hot water boiler without a furnace or with a gas afterburning furnace where hot gases from industrial or metallurgic processes or any other flows of processing products are used as heat source.

Mobile boiler plant - a transportable boiler plant with a travel carriage.

Transportable boiler plant - a set consisting of a boiler, auxiliary equipment, control and protection system, the room (container) where all equipment is installed and transportation devices intended for rapid change of the place of use.

Superheater - device intended to increase steam temperature above the saturation temperature corresponding to pressure in the boiler.

Boiler furnace - device of a stationary boiler intended for combustion of organic fuel, partial cooling of combustion products and cinder emission.

Atomizer - device for supply, atomizing and distribution of liquid fuel injected into the boiler furnace in the air stream.

Economizer - device heated with fuel combustion products and intended for heating or partial evaporation of water supplied to the steam boiler.

Self-contained economizer - an economizer built into a boiler or a gas duct and used to heat water which is completely or partially utilized outside the boiler or a stand-alone economizer used to heat water which is completely or partially utilized in the steam boiler.

Appendix 2

to federal rules and regulations

in the field of atomic energy use

"Rules for arrangement

and safe operation of steam

and hot water boilers for

nuclear facilities",

approved by Order of the Federal

Environmental,

Industrial and Nuclear Supervision Service

dated March 19, 2018 No. 113

(for reference)

DEFINITIONS OF SIMILAR AND REFERENCE JOINTS

Similar weld joints are a group of weld joints with the following common characteristics:

1) welding technique;

2) grade (combination of grades) of the basic metal (weld joints between the parts made of different steel grades requiring application of welding materials of the same grades (combinations of grades) in accordance with the technical process may be united into the same group);

3) grade (combination of grades) of the welding materials (weld joints performed with the use of different welding materials of the grades (combinations of grades) that may be used to weld parts made of the same steel in accordance with the technical process may be united into the same group; electrodes shall have the same coating type (basic, rutile, cellulose, acid);

4) nominal thickness of welded parts at the welding zone (joints with the nominal thickness of parts at the welding zone within one of the following ranges may be united into the same group:

up to 3 mm inclusive;

exceeding 3 mm and up to 10 mm inclusive;

exceeding 10 mm and up to 50 mm inclusive;

over 50 mm).

For corner, T-shaped and overlapping joints the above-mentioned ranges shall be applied to weld-on parts; thickness of the basic parts may be disregarded;

5) curvature radius of the parts at the welding zone (weld joints between the parts with the curvature radius at the welding zone (for pipes - with half of the nominal outer diameter) within one of the following ranges may be united into the same group:

up to 12.5 mm inclusive;

exceeding 12.5 mm and up to 50 mm inclusive;

exceeding 50 mm and up to 250 mm inclusive;

over 250 mm (including flat parts).

For corner, T-shaped and overlapping joints the above-mentioned ranges shall be applied to weld-on parts; curvature radii of the basic parts may be disregarded;

6) type of weld joint (butt, corner, T-shaped, overlapping); corner, T-shaped and overlapping joints may be united into the same group except for corner weld joints for welding of pipes (nozzles) to boiler components;

7) edge preparation type;

weld joints with one of the following types of edge preparation may be united into the same group:

with single-side edge preparation and the beveling angle exceeding 8°;

with single-side edge preparation and the beveling angle of up to 8° inclusive (narrow beveling);

with double-side edge preparation;

without any edge preparation;

8) root layer welding technique: on permanent backing (backing ring), on melted backing, without any backing (free temper bead formation), with weld root back run;

9) thermal regime of welding: with preliminary and concurrent heating, without any heating, with layer-by-layer cooling;

10) weld joint heat treatment regime.

A reference weld joint is a joint cut out of manufacturing weld joints or welded separately but identical or similar to manufacturing weld joints and intended for destructive control in the course of welding technique validation or verification of quality and properties of manufacturing weld joints.

Appendix 3

to federal rules and regulations

in the field of atomic energy use

"Rules for arrangement

and safe operation of steam

and hot water boilers for

nuclear facilities",

approved by Order of the Federal

Environmental,

Industrial and Nuclear Supervision Service

dated March 19, 2018 No. 113

REQUIREMENTS FOR THE BOILER CERTIFICATE CONTENT

The boiler certificate shall include the following information in the scope to be defined by the manufacturing organization depending on the boiler type:

1) general information:

name and address of the manufacturing organization;

manufacturing (production) date;

boiler type (model);

boiler name and purpose;

serial number of the boiler;

design service life of the boiler;

design lifetime of the boiler and the main components;

design number of start-ups;

dimensions of the boiler and its components;

2) basic technical characteristics and parameters:

design fuel type and its calorific value, MJ/kg (kcal/kg);

fuel flow rate, m/h (t/h);

type and characteristics of the furnace (burners);

design, working and test pressure, MPa;

maximum permissible flow resistance of the boiler under the rated capacity, MPa;

minimum permissible pressure at the nominal temperature, MPa;

nominal steam temperature at the boiler outlet, °C;

design superheated steam (liquid) temperature, °C;

nominal liquid temperature at the boiler inlet, °C;

nominal and maximum liquid temperature at the boiler outlet, °C;

rated, minimum and maximum permissible steam capacity, t/h;

rated, minimum and maximum heating capacity, kW;

heating surface of the boiler and main components, m;

volume, m;

minimum and maximum permissible liquid flow rate, m/h;

3) information on protection devices (type, number, places of installation, cross-section area, nominal diameter, steam or liquid flow coefficient, start value (range));

4) information on liquid (water) level indicators (type of indicator, number, places of installation);

5) information on the main valves (number, nominal diameter, nominal pressure, operating parameters, casing material, places of installation);

6) information on the main measuring, control, alarm, adjustment and automatic protection devices (number, type (brand));

7) information on the pumps (type, number, operating parameters, drive type);

8) information on the main boiler components made (manufactured) of steel sheets (number, dimensions, material, welding and heat treatment);

9) information on the main boiler components made (manufactured) of pipes (number, dimensions, material, welding and heat treatment);

10) information on nozzles, covers, end plates, adapters and flanges (number, dimensions, material);

11) information on the heat transfer medium (name, maximum permissible application temperature, self-ignition temperature in open space, freezing temperature, boiling temperature, boiling temperature change (curve) depending on the pressure);

12) pictures, diagrams, drawings of the boiler and its main components and other documents (consolidated list of factory modifications, packing list, specifications with basic dimensions of assembly units);

13) records of technical examination results, information on replacement and repair of the main boiler components.