Approved by the
Decree of the Federal
Environmental, Industrial
and Nuclear Supervision
Service dated November 14, 2018. No. 553

FEDERAL RULES AND REGULATIONS
IN THE FIELD OF ATOMIC ENERGY USE "REGULATIONS FOR CONTROL OF
METAL OF EQUIPMENT AND PIPELINES OF NUCLEAR POWER
INSTALLATIONS AT MANUFACTURE AND ASSEMBLY"

(NP-105-18)

I. Purpose and scope of application

1. These Federal Rules and Regulations in the Field of Nuclear Energy Use "Regulations for Control of Metal of Equipment and Pipelines of Nuclear Power Installations at Manufacture and Assembly" (NP-105-18) " (hereinafter referred to as the Rules) were developed in compliance with Federal Law dated November 21, 1995. No.170-FZ "On atomic energy use", Provisions for development and approval of federal rules and regulations in the field of atomic energy use approved by Decree of the Government of the Russian Federation No. 1511 dated 1 December 1997 N 1511 (Code of legislation of the Russian Federation, 1997, N 49, art. 5600; 2012, N51, art. 7203).

2. These Rules establish requirements to control (procedure of performance, the types, scope, methods, standards of quality evaluation based on control results) of the condition of the base metal, welded joints and weld metal surfaces (hereinafter, unless otherwise specified, metal) in the design, engineering, manufacture and installation of equipment and pipelines of nuclear power installations referred to in paragraph 3 of these Rules.

3. The manufacture and installation must involve carrying out control of condition of the metal:

a) the equipment and pipelines covered by the federal rules and regulations in the field of atomic energy use "Rules of the design and safe operation of the equipment and pipelines of nuclear power installations" (NP-089-15) approved by the order of the Federal Service for Environmental, Industrial and Nuclear Supervision dated December 16, 2015 No. 521 and registered by Russia's Justice Ministry on February 09, 2015 No. 41010 (hereinafter referred to as NP-089-15);

b) the equipment and pipelines working under excessive, hydrostatic or vacuum pressure and referred to elements of the third class of safety not subject to NP-089-15;

c) supports and hangers, fasteners of equipment and pipelines specified in subparagraphs "a" and "b" of this paragraph;

d) internals of water-water reactors and reactors on fast neutrons;

e) metalworks of fuel holding pools, refueling ponds, spent fuel pools of nuclear power installations.

4. The manufacturing and (or) installation organization must monitor the condition of the metal of equipment and pipelines in accordance with the process documentation for the performance of control developed taking into account the requirements of the engineering documentation.

5. Engineering documentation as regards the control of the metal condition shall be subject to conformity assessment in the form of examination.

6. Process documentation for the performance of control (hereinafter referred to as process documentation) of equipment, parts and components of pipelines manufactured (mounted) before the entry into force of these Rules or being in the manufacture (installation) at the time of their entry into force, shall not be subject to revision.

7. Control of the condition of the metal equipment and pipelines in the manufacture and installation must be performed by personnel who have passed the appropriate theoretical and practical training and have been admitted to unsupervised operation in the manner prescribed by GOST R-50.05.11-2018 "Conformity assessment system in the field of atomic energy use. Personnel in the non-destructive and destructive testing of metal. Requirements and qualification procedure" approved by Order of the Federal Agency on Technical Regulation and Metrology dated March 6, 2018 No. 122-st (Standartinform, 2018).

8. The terms and definitions used are given in Appendix No. 1 to these Rules.

II. General control requirements

9. The condition of the metal of equipment and pipelines in the manufacture and installation shall be controlled in order to:

a) detect metal discontinuities;

b) identify mechanical characteristics of metal;

c) identify the chemistry and structure of metal;

d) identify dimensions of welded joints and deposited surfaces.

10. The results of control shall be registered in the deliverables of the manufacturer and (or) installation contractor.

11. Metal condition control shall be performed by non-destructive and destructive methods.

12. The scope, zones, and methods of metal condition control shall be specified in design documents.

13. Defects of metal of details and assembly units of equipment and pipelines are eliminated according to the procedure established by standardization documents for the basic metal and the Federal rules and regulations in the field of atomic energy use regulating requirements for welding and surfacing of the equipment and pipelines of nuclear power facilities.

14. Cracks, delamination, burns, blowhole, lappings, shrinkholes, undercuts, poor penetration, aggregations, multiple inclusions, spatter identified by visual inspection of welded joints and surfacing materials are not allowed. Straw, brown or blue tarnishing colors on the deposited surfaces of titanium alloys are not allowed.

15. Control of the condition of equipment and pipelines metal, the conduct of which after the assembly or installation operations is limited or impossible, shall be performed before the start of installation or before the completion of the corresponding installation operation.

III. Categories of welded joints
(weld surfaces)

16. Categories of welded joints shall appointed by the engineering (design) organization according to the criteria given in paragraphs 17 - 23 hereof and are specified in the engineering (design) documentation.

17. For welded joints of equipment and pipelines of nuclear power plants with water-moderated reactors and pressure tube reactors, the following categories of welded joints are established:

a) category I - welded joints of group A equipment and pipelines;

b) category II - welded joints of group B equipment and pipelines, working in contact with the radioactive coolant;

c) category III - welded joints of group B equipment and pipelines, not working in contact with the radioactive coolant, as well as welded joints of group C equipment and pipelines.

18. Welded joints of II and III categories of equipment and pipelines of nuclear power plants with water-moderated reactors and pressure tube reactors, depending on the operating pressure, are divided into the following subcategories:

a) subcategory IIa - welded joints operating under pressure above 5 MPa;

b) subcategory IIb - welded joints operating under pressure up to 5 MPa inclusive;

c) subcategory IIIa - welded joints operating under pressure above 5 MPa;

d) subcategory IIIb - welded joints operating under pressure above 1.7 MPa to 5 MPa inclusive;

e) subcategory IIIc - welded joints operating under pressure from 1.7 MPa and below atmospheric pressure (under vacuum).

19. For welded joints of equipment and pipelines of nuclear power plants with fast breeder reactors with liquid sodium coolant, the following categories of welded joints are established:

a) category In - welded joints of equipment and pipelines of group A, and also group B subject to requirements in design documentation;

b) category IIn - welded joints of equipment and pipelines of group B working in contact with the liquid metal coolant and gas <1> (except for the category relating to In);

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

<1> Gas refers to argon that is used for pressurization, and (or) a coolant vapor.

c) category II - welded joints of group B equipment and pipelines, working in contact with the liquid metal coolant and gas;

d) category III - welded joints of group C equipment and pipelines.

20. Welded joints of IIn and II categories of equipment and pipelines of nuclear power plants with fast breeder reactors with liquid sodium coolant, depending on operating conditions, are divided into the following subcategories:

a) subcategory IIna - welded joints in contact with liquid metal coolant and (or) gas operating at temperatures above 350 °C regardless of pressure;

b) subcategory IInv - welded joints in contact with liquid metal coolant and/or gas at temperatures up to 350 °C, inclusive, regardless of pressure (except welded joints related to IIns subcategory);

c) subcategory IIns - welded joints in contact with gas and working at pressure up to 0.07 MPa inclusive and temperature up to 150 °C inclusive;

d) subcategory IIa - welded joints not in contact with the liquid metal coolant and gas, working at operating pressure over 2 MPa;

e) subcategory IIb - welded joints not in contact with the liquid metal coolant working at operating pressure up to 2 MPa inclusive.

Welded joints of category III are divided into subcategories IIIa, IIIb and IIIc identical to the subcategories specified in subparagraphs "c" - "e" of paragraph 18 hereof.

21. For welded joints of the welding attachments which are not loaded by pressure of details with the equipment and pipelines, the category is appointed according to paragraphs 17 - 20 hereof.

The requirements of this paragraph do not apply to welded joints of equipment and pipelines with parts used in maintenance (decking, stairs) and measurement systems (brackets). The need and scope of control of these welded joints is established by the design documentation.

22. The category of butt welded joints of non-replaceable elements of internals located in the irradiation zone at the design neutron fluence above 1.5·10²⁵ neutrons/m² (E 0.1 MeV) shall be set equal to:

a) II - for water-moderated reactors;

b) IIn - for fast breeder reactors with liquid sodium coolant.

23. Category IIIc is set for welded joints of:

a) equipment and pipelines working under excessive or vacuum pressure and referred to elements of the third safety class not covered by the Federal rules and regulations in the field of atomic energy use;

b) parts of supports and hangers of equipment and pipelines specified in paragraphs 17 - 20 hereor and in subparagraph "a" of this paragraph;

c) metalworks of fuel pools, refueling pools, spent nuclear fuel pools of nuclear power installations.

Subparagraph "b" of this paragraph does not apply to welded joints specified in paragraph 21 of these Regulations.

24. The scope of nondestructive testing of the metal of deposited surface of the edges for welding and quality assessment standards according to the testing results are established according to the category of the corresponding welded joint.

25. When carrying out non-destructive testing of metal of sealing and anti-corrosion weld surfaces, no category is assigned.

26. Engineering (design) organization is entitled to designate categories of welded joints, which have to meet higher safety requirements than those stated in paragraphs 17 to 23 hereof (except subparagraph "a" of paragraph 17 and subparagraph "a" of paragraph 19 hereof).

27. For the equipment and pipelines which are not specified in paragraphs 17 - 20, 22 and 23 hereof, categories of welded joints are not established by these Regulations. Methods and scope of metal control shall be established by the engineering (design) organization in design documentation, and quality assessment standards shall correspond to the standards established for welded joints of category III.

IV. Control tools and methods

28. When carrying out nondestructive testing of metal condition, the standardized unified methods of control included in the Consolidated list of standardization documents in the field of atomic energy use applied on the obligatory basis (hereinafter, the Consolidated list), stipulated by Regulations on standardization concerning products (works, services) subject to requirements related to safety assurance in the field of atomic energy use, and also processes and other standardization objects associated with such products, approved by Decree of the Government of the Russian Federation dated July 12, 2016 shall be applied. No. 669 (Russian Federation Code, 2016, No. 29, Art. 4839). The use of other control methods is possible upon the completion of compliance assessment procedure in the form of tests.

Used means of metal condition control shall meet the requirements of the standardized unified control methods.

29. Metrological support of the control of metal condition of equipment and pipelines shall be carried out in accordance with the legislation on provision of uniformity of measurements.

V. Materials used for
non-destructive testing

30. Materials used for nondestructive testing shall be subject to incoming inspection. The results of incoming inspection shall be recorded in logs and (or) registered in the form of acts.

31. Materials used for nondestructive testing shall comply with the requirements of standardization documents for these materials.

32. The organization performing inspection shall establish the procedure to manage materials, organize their accounting and provide required conditions for their storage.

VI. Non-destructive control methods

33. Non-destructive testing shall be carried out by the following methods:

a) visual and measuring control, including television control;

b) liquid penetrant control;

c) magnetic powder control;

d) ultrasonic control;

e) tightness control;

f) radiographic control;

g) measurement control using a metal reference gauge (a ball);

h) hardness control;

i) eddy current control.

34. Other control methods may be used that have passed the compliance assessment in the form of tests in the presence of quality assessment standards based on the results of the corresponding control method.

VII. Non-destructive testing of welded joints and
weld surfaces

35. Methods and scope of non-destructive testing of welded joints (weld surfaces) and quality assessment standards based on the results of the control shall be established by the engineering (design) organization taking into account the categories of welded joints (weld surfaces).

Visual and measuring control

36. Visual and measuring control shall be carried out prior to control by other methods.

37. Measurement control of welded joints and pre-weld edges shall be performed at least every 1.0 m and at least at three points of each welded joints and pre-weld edge.

38. If there are more than fifty welded joints of the same type of pipes with a nominal outer diameter of up to 90.0 mm inclusive on one product, the scope of measurement control may be reduced to 10% of the total number of welds to be measured and up to one measurement on each controlled welded joint.

39. On cylindrical surfaces, measurement control of anti-corrosion surfacing thickness shall be carried out at least every 0.5 m in the axial direction and at intervals of 60° around the circumference at manual surfacing and 90° at auto-surfacing. Flat and spherical surfaces of anti-corrosive weld overlays shall be measured at least once at each segment of 0.5 x 0.5 m for manual surfacing and at each segment 1.0 m long (in the direction of weld overlay) and 0.5 m wide for automatic surfacing.

40. Visual inspection of sealing and guiding surfaces shall be carried out over the entire area, including the side surfaces and the area of fusion with the base metal, measurement control shall be carried out in accordance with the process documentation.

Liquid penetrant test

41. Sensitivity class for a liquid penetrant test shall be established in the design documentation.

42. For welded joints of I, In, II, IIn categories and corrosion-resistant weld overlays, as well as all categories of welded joints of parts made of titanium and aluminum alloys, the second sensitivity class is established.

Magnetic powder test

43. Sensitivity level for magnetic powder test shall be established in the design documentation. For welded joints of I, In, II, IIn categories, sensitivity level B is set.

44.  Welded joints of parts and assembly units of equipment and pipelines of pearlite steel and (or) of high-chromium steels, as well as the edges of parts, pre-welded with pearlite and (or) high-chromium materials shall be subject to magnetic powder test.

Radiographic inspection

45. Radiographic inspection of welded joints is carried out through one wall, and where it is technically impossible - through two walls. The technical impossibility of radiographic inspection shall be established in the design documentation.

46. Control sensitivity is determined by the radiation thickness. In case of applying radiation through two walls, the control sensitivity shall be established according to the total nominal value of these walls.

Ultrasonic inspection

47. When carrying out ultrasonic inspection, preference shall be given to the use of controls with automatic recording of results and automated controls.

48. In anti-corrosive surfacing, the zone of fusion of the deposited surface with the base metal and (or) with the weld metal (when surfacing on the seam zone) shall be controlled. The metal under surfacing shall be controlled subject to an appropriate requirement of design documentation.

49. In the welded joints of clad steels, the metal of the welded joints, the area of fusion of the deposited surface with the weld metal and the base metal in the areas adjacent to the weld shall be controlled.

Control using a metal reference gauge (a ball)

50. Control of welded joints by a metal reference gauge (ball) shall be carried out for pipes with nominal internal diameter not exceeding 70.0 mm, if there is a relevant requirement in the design documentation.

Tightness control

51. Tightness control is carried out in ases provided by the design documentation.

52. Welded joints of steel and iron-nickel alloys with a nominal thickness more than a thin-walled made of welded parts up to 8.0 mm inclusive, and welded joints of aluminum alloy parts up to 10.0 mm inclusive are subject to tightness control.

53. Tightness class shall be determined in accordance with table No. 1 hereof.

Table No. 1

54. Tightness class shall be established in the design documentation.

55. The specific method of tightness control shall be appointed by the manufacturer (installation organization) and indicated in the process documentation.

Hardness control

56. Hardness control of the weld deposit of sealing surfaces of steel parts shall be carried out using Rockwell method pursuant to the standardization document included in the Consolidated list.

57. Hardness control of the weld deposit of sealing surfaces of titanium alloy parts shall be carried out using Vickers method pursuant to the standardization document included in the Consolidated list.

Eddy current control

58. The need for eddy current control shall be established in the design documentation.

Control procedure

59. The sequence of non-destructive testing by various methods shall be established in the process documentation.

60. Visual and measuring control shall be carried out both before and after heat treatment of welded joints and weld surfaces. After heat treatment, measurement control of relative position of the axes of welded parts only is allowed.

61. Non-destructive testing of welded joints and weld surfaces shall be carried out after each stress relief (including multiple one).

62. If a welded joint (welded part) is subject to mandatory radiographic and ultrasonic control, radiographic control before heat treatment (including complete heat treatment) with the mandatory continuous ultrasonic control after its implementation is allowed.

63. Non-destructive testing of welded joints shall be carried out after machining with the removal of a part of weld or deformation, if such treatment is stipulated in the design documentation. Radiographic control may be carried out before the final machining of the welded joint, if the total allowance for this treatment on each side does not exceed 20% of the nominal thickness of the welded parts. The required control sensitivity shall be selected according to the radiation wall thickness after machining.

64. If welded joints with transverse seams of spirally curved pipes of heat exchange surfaces are not available for continuous control, such control may be carried out after the end of their manufacture, before the bending of pipes.

65. Tightness control shall be carried out after pressure testing. Tightness control using liquid methods may be combined with hydraulic tests.

Scope of control

66. The control area of the welded joint or its part must include the entire volume (surface) of the welded joint, as well as adjacent areas of the base metal in both directions from the weld line with width of at least:

a) for butt welded joints, performed by arc or electron-beam welding:

1) 5.0 mm - in case of nominal thickness of welded parts up to and including 5.0 mm;

2) of nominal thickness of welded parts - in case of nominal thickness of welded parts from 5.0 up to and including 20.0 mm;

3) 20.0 mm - in case of nominal thickness of welded parts over 20.0 mm;

b) 3.0 mm - for corner, tee, lap and edge welded joints, performed by arc or electron-beam welding, irrespective of thickness of welded parts;

c) 50.0 mm - for welded joints made using electroslag welding, irrespective of thickness of welded parts.

Control area of welded joints for welding of pipes into pipe plates shall be established in accordance with the requirements of design documentation.

67. In welded joints of various nominal thickness, the width of the control areas of the base metal must be determined separately for each of the parts to be welded, depending on their nominal thickness.

68. Control areas in respect of deposited part or its part must include the whole volume and surface of deposited metal, the area of fusion with the base metal or welded joint and also, if required by the design documentation, adjacent base metal or weld metal (in case of deposit welding onto a weld area).

69. When accessible to visual and capillary control, the welded joints must be controlled both on the outside and on the inside.

70. Non-destructive control of welded joints and deposited surfaces in terms of scope of control shall be divided into complete control (scope - 100%) and selective control (scope - 50, 25, 10 or 5%).

Complete control must be carried out along the whole length of each welded joint or across the whole surface of every deposited area.

Selective control must be carried out on sections of welded joints and deposited surfaces or separate welded joints and deposited.

71. Selective control of sections must be carried out on welded joints with straight-line and other unclosed welds, welded joints of parts with nominal outer diameter of over 250.0 mm with circular welds as well as on deposited surfaces of parts with the size over 1.0 m in any direction. The ratio of total length (surface area) of controlled sections to the total length of welded joint (deposit area) must be not less than established scope of selective control.

72. In case of selective control of welded joints of parts with nominal outer diameter up to and including 250.0 mm with circular welds, separate welded joints must be controlled along their full length. The number of controlled welded joints must be identical for each group of welded joints of the same type for each item.

73. The controlled sections or welded joints referred to in paragraphs 71 and 72 of these Rules must be selected from the most difficult to perform. If there are no such sections, then the controlled sections must be evenly distributed along the length of the controlled welded joints (across the deposited surface).

74. Irrespective of the scope of selective control, the areas of crossing and conjunction of welded joints must be controlled with all stipulated methods of each welded joint at the distance of at least three times the nominal thickness of welded parts to each side of the point of intersection (conjunction) of joint axes.

75. If any discontinuities, the size of which exceeds the allowed size, are discovered during selective control, then additional control using the same method must be carried out in the double scope with obligatory control of areas adjacent to defective areas. In case of negative results of additional control, complete control must be performed.

In case of selective control of welded joints with circular welds of parts with nominal outer diameter up to and including 250.00, the requirements of this paragraph shall apply to welded joints of the same type, performed by the welder who introduced the defects.

At the same time the following condition must be fulfilled. Additional control of areas that were not controlled shall be performed in twice the scope of welded joints of the same type performed by the same welder during one shift (during which the defective area of the weld has been welded) in case of automatic welding and during two shifts in case of manual arc welding (the shift during which the defective area of the weld has been welded and the previous shift).

76. Inaccessibility of specific welded joints for control by any given method, as well as substitution of a control method for another and its scope in case of substitution must be specified in the design documentation.

77. Complete capillary control must be performed on all welded joints of austenitic steel parts performed using niobium-containing welding materials as well as welded joints of austenitic steel parts with anti-corrosion weld overlay containing niobium. In other cases the scope of capillary control of weld joints of austenitic steel parts shall be established in design documentation.

78. Welded joints (weld overlays) of titanium alloy parts must be subjected to complete capillary control irrespective of welded joint category, including adjacent areas of base metal with width of at least 20.0 mm to both sides of the weld.

79. Edges of alloyed steel parts, pre-deposited with pearlite or high-chromium welding materials, including the area of fusion of weld overlay with the base metal, must be subjected to complete capillary or magnetic powder control irrespective of welded joint category.

80. The welded joints of pearlite steel parts with austenitic steel parts with pre-deposition of edges, performed by austenitic welding materials, must be subjected to repeated capillary control of the fusion area between the pre-deposition with the base metal.

81. Selective capillary or magnetic powder control of welded joints performed by the same batch of welding materials may be reduced upon decision of the manufacturing or installation organization, if during control of the first twenty welded joints of the same type with total length of controlled welds of at least 10.0 m no cracks were revealed.

The specified requirement shall not apply to welded joints of categories I, Iн, II, IIн of pearlitic steel parts, alloyed with vanadium or niobium, and austenitic steel parts, performed using welding niobium-containing materials as well as to welded joints of all categories of parts made of steels of different structural classes.

82. The reduced scope of selective capillary or magnetic powder control must be at least 5% for welded joints of carbon steel and (or) silicon-manganese steel parts and for welded joints of austenitic steel parts made using niobium-free welding materials, and in other cases - at least 15%.

If even a single crack is detected during selective control subject to this paragraph, then all the welded joints made using the same batch of welding materials as the defective one shall be subject to complete control.

83. If it is technically impossible to perform radiographic and (or) ultrasound control of welded joints, it is allowed to perform layer-by-layer visual control in the process of welding with recording of results and subsequent capillary or magnetic powder control of welded joint in accessible points.

84. It is allowed to substitute radiographic control of the same scope for ultrasound control of welded joints not subject to radiographic control.

85. If it is technically impossible to perform radiographic control of category IIв and IIIс  welded joints, as required by the design documentation, it is allowed to perform ultrasound control in the same scope.

86. Welded joints of zirconium alloy parts with austenitic steel parts shall be subject to complete radiographic control.

87. Category IIв and IIIс welded joints, designed to operate at pressures up to 0.07 MPa, shall not be subject to radiographic control which must be reflected in the design documentation.

88. For category IIв and III welded joints of equipment and pipelines with nominal outer diameter up to and including 200.0 mm and with nominal wall thickness less than 15.0 mm it is allowed to decrease the scope of radiographic control but not more than to the half of original scope.

89. If a welded joint is subject to selective radiographic control and to ultrasound control, but the latter is technically impossible, then the scope of radiographic control must be doubled.

90. Radiographic control of corner, tee, edge and lap welded joints must only be performed if the total radiation thickness of the X-rayed metal does not exceed 100.0 mm; the rated height of corner weld or thickness of the weld in the X-raying direction must be at least 0.2 of the total radiation thickness.

91. Corner, tee, edge and lap welded joints with structural clearance as well as corner and tee joints of pipes with nominal internal diameter less than 100.0 mm are not subject to ultrasound control. These welded joints must undergo layer-by-layer complete visual control, as well as complete capillary control.

92. Welded joints for welding of nozzles and pipes with nominal inner diameter from 16.0 to and including 30.0 mm to equipment and pipelines are subject to radiographic control in the scope of at least 50% of length of the corresponding weld with obligatory performance of layer-by-layer visual control in the process of welding. Reduction of the scope of control of the weld shall not be taken into ccount when designating the total scope of selecive control.

Radiographic control of welded joints connecting nozzles of pipes with nominal inner diameter up to and including 16.0 mm shall be performed if so required by the design documentation.

93. Methods and scope of nondestructive control of welded joints of pearlitic and (or)  high-chromium steel parts are given in Table No. 2 of these Rules. The scope of control of welded parts of different nominal thickness shall be established according to the thickness of the part with the least wall thickness at the point of welding or according to the thinnest point in case of varying cross-section of the welded joint.

Table No. 2

The requirements of Table No. 2 of these Rules do not apply to the welded joints for welding of pipes into pipe plates and welded joints of equipment and(or) pipelines with parts not under pressure.

94. The methods and scope of nondestructive control of welded joints of parts made of austenitic steels, iron-nickel alloys and of parts made of austenitic steels with parts made of iron-nickel alloys are given in Table No. 3 of these Rules.

Table No. 3

95. The methods and scope of nondestructive control of welded joints of  parts made of austenitic steels or iron-nickel alloys with parts made of pearlitic steels or parts made of high-chromium steels are given in Table No. 4 of these Rules.

Table No. 4

The requirements of Table No. 4 do not apply to the welded joints for welding of pipes into pipe plates and welded joints of equipment and(or) pipelines with parts not under pressure.

96. Methods and scope of nondestructive control of welded joints made of aluminum alloys are given in table No. 5 of these Rules. The scope of ultrasound control of category I welded joints with thickness of 6.0 mm and more shall be established by design documentation.

Table No. 5

97. Methods and scope of nondestructive control of welded joints of parts made of titanium alloys are given in Table No. 6 of these Rules.

Table No. 6

The requirements of Table No. 6 do not apply to the welded joints for welding of pipes into pipe plates.

98. Methods and scope of nondestructive control of pre-deposited welds of edges of parts made of pearlitic steels and of high-chromium steels are given in Table No. 7 of these Rules.

Table No. 7

99. Anti-corrosion weld deposits on parts and assembly units made of pearlite steels are subject to visual, measuring and ultrasound control in 100% scope as well as capillary control if required in the design documentation. The areas of radius bend in points of connection of two deposited surfaces are not taken into account when determining the scope of ultrasound control.

100. The methods and scope of non-destructive control of welded joints for welding of pipes into pipe plates and into collectors are given in the Appendix No. 2 to these Rules.

101. Methods and scope of nondestructive control of deposited sealing and guiding surfaces are given in Appendix No. 3 to these Rules.

102. Methods and scopes of non-destructive testing of corner, tee, edge and lap welded joints of parts, which do not operate under pressure, with equipment and pipelines are given in Table No. 8 of these Rules.

Table No. 8

Standards of quality assessment based on the results of nondestructive
control of welded joints and deposited surfaces

103. Quality assessment standards are adopted:

a) for control of butt welded joints of parts of different thickness - according to  the rated thickness of a thinner part;

b) for control of angular and tee welded joints - according to the rated height of the angular weld;

c) for control of edge and lap welded joints - according to the double rated thickness of a thinner welded part;

d) for control of welded joints for welding of pipes into pipe plates - according to the nominal pipe wall thickness;

e) for radiographic control of welded joints of pipes or other cylindrical parts through two walls - according to the nominal thickness of one wall;

f) for control of welded joints done with boring out - according to the nominal wall thickness (in the point of boring), which shall be specified in the design documentation.

104. Length of welded joints of cylindrical and spherical parts must be determined according to their outer surface (for butt welded joints with circular welds, corner and tee welded joints - according to the outer surface of welded part near the weld edge.

105. Standards of assessment of quality of welded joints and deposited surfaces based on the results of nondestructive control are given in Appendix No. 4 to these Rules.

Standards of assessment of quality of welded joints upon the results of eddy current testing shall be established by the design documentation.

VIII. Destructive control of welded joints

Carrying out and scope of destructive control

106. Destructive control must be carried out:

a) for testing quality of welding (depositing) materials by testing samples cut out from reference welded joints (deposits);

b) for verifying compliance of characteristics of metal of production welded joints to the established requirements by testing samples cut out from reference production welded joints.

107. The following must be determined during destructive control of welded joint (deposit):

a) chemical composition;

b) mechanical properties at regular and increased temperatures (tensile strength, yield strength, relative elongation, contraction);

c) impact resistance;

d) ductile to brittle transition temperature (or it is confirmed) for pearlite and high-chromium materials;

e) ferrite content in austenitic weld deposit;

f) resistance to inter-crystalline corrosion of austenitic metal.

108. The following procedures must be performed during destructive control of metal of welded joints and deposited parts:

a) metallographic analysis;

b) determination of tensile strength of welded joints;

c) mechanical testing for static bending;

d) mechanical testing for flattening of welded pipes.

109. Destructive control must be carried out in accordance with the requirements:

a) in regard to chemical analysis - Appendix No. 5 to these Rules;

b) in regard to mechanical analysis - Appendix No. 6 to these Rules;

с) in regard to determination or confirmation of ductile to brittle transition temperature - Federal Rules and Regulations in the Field of Atomic Energy Use, regulating standards of calculation of strength of equipment and pipelines of nuclear power facilities;

d) in regards to inter-crystalline corrosion resistance test - paragraph 127 of these Rules;

e) in regards to metallographical tests - Appendix No. 7 to these Rules;

e) in regards to measurement of ferrite content in weld deposit - paragraph 128 of these Rules;

f) in regards to measurement of hardness of weld deposits - Appendix No. 3 to these Rules.

110. Types of samples for mechanical analysis of weld metal, weld deposit and welded joints must comply with the requirements of the document on standardization, included in the Consolidated list.

111. The number of samples for carrying out mechanical tensile testing must be at least two for each temperature and at least three during impact bending testing for each temperature.

For other types of tests the number of samples must be no less than specified in corresponding document on standardization.

112. In case of unsatisfactory results of chemical analysis, inter-crystalline resistance testing or of any type om mechanical testing, repeated tests must be carried out for the relevant parameter on doubled number of samples.

113. In case of unsatisfactory results of metallographic analysis or measurement of ferrite content a new reference welded joint (weld, weld deposit) must be made and the tests repeated in the same scope.

The results of repeated tests shall be definitive.

Reference production welded joints

114. Control of production welded joints must be carried out:

a) for bodies of group A equipment, including steam generator primary circuit header;

b) for bodies of group B equipment, in cases provided for by the design documentation.

115. During control of production welded joints a reference production welded joint is made. The reference production welded joint is subject to nondestructive control to the extent corresponding the controlled production welded joint.

Destructive control must be carried out by testing samples cut out from reference production welded joints.

116. Reference production welded joint must be identical to the controlled production welded joint in terms of make (modification thereof) heat number and base metal semi-finished product type, in terms of grade and batch (combination of batches) of welding materials, in terms of type of welded joint, nominal thicknesses and outer diameters of welded parts, welding method and welding conditions as well as conditions of preheating, concurrent heating and heat treatment.

If several batches of welding materials are used for controlled production welded joint, then a corresponding number of reference production welded joints must be made.

It is allowed to make reference production welded joints with dimensions different from the dimensions of respective production welded joints, provided that the ratio of maximum and minimum thicknesses and ratio of outer diameters of parts of production welded joint and reference production welded joint must not exceed:

a) for group A equipment - 1.25;

b) for group B equipment - 2.0;

a) for welded connections made using electroslag welding, irrespective of equipment group - 1.25.

For reference production welded joints with longitudinal welds the ratio of diameters may be disregarded.

When provided for by the design documentation, in case of nominal outer diameter of production welded joints over 500.0 mm it is allowed to make flat reference production welded joints.

117. The design documentation for equipment and pipelines referred to in the paragraph 114 of these Rules must provide for production of special parts or corresponding increase of length of production parts ensuring the possibility of making a reference production welded joint subject to requirements of paragraph 116 of these Rules.

118. During control of reference production welded joints the following characteristics of the welded joint must be determined:

a) tensile strength and bend angle at normal temperature;

b) tensile strength at increased temperature;

c) inter-crystalline corrosion;

d) ductile to brittle transition temperature of metal of weld, fusion area and weld adjacent zone;

d) chemical composition of weld metal;

e) mechanical properties of weld metal.

119. Determination of tensile strength and bend angle for welded joints of austenitic steels must be carried out in cases when controlled production welded joints are subjected to heat treatment, heating for bending, pressing or other heat procedures or if it is required in the design documentation.

120. Determination of tensile strength of a welded joint at increased temperature must be carried out if so required by the design documentation for the controlled article.

121. Determination of tensile strength for welded joints of parts made of steels of different structural classes (for example, pearlitic and austenitic) must only be carried out if so required by the design documentation with specification of standards of assessment of quality of control.

122. Inter-crystalline corrosion resistance tests must only be carried out for welded joints of austenitic steels if so required by the design documentation.

123. Ductile to brittle transition temperature of metal of weld, fusion area and weld adjacent zone of the reference production welded joint must be determined if so required in the design documentation.

124. Determination of mechanical properties and ductile to brittle transition temperature shall be carried out taking into account minimum and maximum duration of temperings, provided for corresponding production welded joints of the article.

Quality assessment standards based on the results of destructive control

Mechanical tests

125. Indices of mechanical properties of welded joint, weld (deposit) metal must be no lower than those given in Appendix No. 6 to these Rules. For materials of welded joints not included in Appendix No. 6 to these Rules, the tensile strength of welded joint shall be established as equal to tensile strength of the least strong material of welded parts.

126. Ultimate tensile strength of welded joints made of aluminum alloys, determined on flat samples with weld reinforcement, must be at least 0.9 of guaranteed tensile strength of base metal in annealed state.

Tensile strength of combined welded joints of parts made of aluminum alloys of different grades shall be determined by the tensile strength of the welded joint of the least strong alloy.

Inter-crystalline corrosion resistance tests

127. The welded joint or weld deposit is resistant to intercrystalline corrosion if the test results conform to the requirements of GOST 6032-2017 "Corrosion-resistant steels and alloys. Test methods of intercrystalline corrosion resistance", approved by Order of the Federal Agency on Technical Regulation and Metrology dated 12.09.2017 No 1054-st (Standardinform, 2017) (hereinafter GOST 6032-2017) The specific test method should be specified in the design document.

Ferrite content measurement
in the weld deposit

128. The ferrite content measurement in the weld deposit should be made in compliance with the requirements of GOST R 53686-2009 "Welding. Determination of Ferrite Number (FN) in austenitic and duplex ferritic-austenitic Cr-Ni stainless steel weld metal", approved by Order of the Federal Agency on Technical Regulation and Metrology dated 15.12.2009. No 1081-st (Standardinform, 2009).

Ferrite content in weld metal should be within 2 to 8% for welded joints of parts operating at temperature up to 350°C inclusive, and from 2 to 5% for the welded joints of parts operating at temperature above 350°C but in any case shall not exceed the upper limit values established in the standardization documents for the relevant welding and hard-facing materials.

IX. Inspection of base metal

129. The inspection of castings should be made in compliance with the requirements of Appendix 8 to these Regulations.

130. Semi-finished products used for manufacture of fasteners, parts and assembly units of equipment  and pipelines should be heat treated if the relevant requirements are available in the design documents.

131. The inspection of semi-finished products (except castings) and fasteners used for manufacturing parts and assembly components of the equipment and pipelines should be made in compliance with the requirements of the standardization documents included in the Summary List.

132. The base metal inspection of the parts and assembly units should be made in compliance with the requirements of the design and project documents for the product.

X. Documentation

133. The control documentation shall be developed by the organization performing control.

Accounting documentation

134. The non-destructive and destructive test results of equipment and pipeline metal shall be recorded in logs.

135. The logs shall contain information which shall be used for recording information into the control conclusion (protocol).

136. The accounting documentation procedure shall ensure that it is possible to restore the control results if the reporting documentation is lost or damaged.

Reporting documentation

137. The reporting documentation shall be drawn up based on the accounting documentation. A registration number shall be assigned to the reporting documentation.

138. The reporting documentation shall be drawn up for each test method used.

139. The test results by each method shall be drawn up by protocols, acts, conclusions or notices with the fixation of the following data at the minimum:

a) name, code or notation (number) of the product;

b) drawing number;

c) information on the grades and melts or lots of used materials with conclusion of their quality following the test;

d) data on performed thermal treatment;

e) test method and scope;

f) date of test;

g) information on revealed defects, places of their location;

h) information on test results after defects remedy;

i) final conclusion on test results.

140. The reporting documentation on inspection of metal of welded joints and (or) weld deposit surfaces should in addition contain information:

a) numbers of inspected welded joints and weld overlays;

b) categories of welded joints;

c) test results of industrial reference welded joints.

141. The reporting documentation should be executed as a hard copy.

142. The conditions for storage of the reporting documentation on non-destructive and destructive testing excluding it loss, damage and unauthorized access to the information contained in it during the designated operation period of the equipment and pipelines should be provided by the manufacturer (installation company).

Appendix 1
to the Federal rules and regulations
in the field of atomic
energy use "Rules of control of
equipment and pipelines metal of
nuclear power installations
during manufacture and installation"
approved by Decree of the Federal 
Service for Environmental,
Industrial and Nuclear Supervision
dated 14.11.2018. No. 553

TERMS AND DEFINITIONS

1. Nuclear power installation is an NPP unit with a pressurized water reactor, or with an ACT heat-pipe cooled reactor, or with a fast breeder reactor with a liquid-metal sodium coolant, or an installation with a research reactor of these types.

2. An inclusion is a cavity in the base metal or weld deposit or weld metal filled with gas, slag or foreign metal.

2.1. Maximum size of singular inclusion a is the maximum distance between two points of the external inclusion outline (figure 1.1).

Figure 1.1. Maximum size a and width b of the inclusion

2.2. Maximum width of the inclusion b is the maximum distance between two points of the external inclusion outline measured in the direction perpendicular to the maximum size of inclusion (figure 1.1).

2.3. A singular inclusion is an inclusion with the minimum distance L from its edge to the edge of any adjacent inclusion not less than a maximum width of each of the inclusions, but not less than a triple maximum inclusion size of the smaller one (of the two inclusions under consideration) (Figure 1.2).

Figure 1.2. Singularity conditions

of the two inclusions under consideration:

a) L  b₁; L  3a₂; a₁> a₂; b₁> b₂;

b) L  3a₁; b₁ a₁; a₁> a₂; b₁> b₂;

c) L  3a₂; b₂ a₂; a₁> a₂; b₁> b₂

2.4. Very small singular inclusions (during radiographic testing) are inclusions, tolerability of which is established depending on their sizes, and on the total number and aggregate reduced area of very small singular inclusions and singular inclusions.

2.5. Large singular inclusions (during radiographic examination) are inclusions with their maximum size exceeding the permitted size of very small singular inclusions, and tolerability is established only depending on the sizes and number without taking account of their area during calculation of the aggregate reduced area and without including them in the total number of very small singular inclusions and single clusters.

3. Root concavity is a depression on the welded joint surface with one-sided seam at its root location (assessed by the maximum depth of root surface from the surface level of welded parts).

4. Concavity of fillet weld is the maximum distance from the seam surface to the line connecting the edge of its surface in one transverse direction (assessed by the maximum depth of seam surface below the specified line).

5. Root convexity (excess fusion) is part of the one-sided weld seam from the part of its root extending above the surface level of welded parts (assessed by the maximum height of root surface above the specified surface).

6. Convexity of butt weld is a part of the butt weld joint extending above the surface level of welded parts (assessed by the maximum height of seam surface above the specified line).

7. Convexity of fillet weld is a part of the fillet weld extending above the line connecting the edge of its surface in one transverse direction (assessed by the maximum height of the surface above the specified line).

8. Indication:

a) during liquid penetrant test is a trace formed by the indicator fluid on the developer layer;

b) during magnetic particle test method is a visible bead length of magnetic powder deposition above the discontinuity.

A reference welded joint is a welded joint executed during metallographic studies of industrial welded joints.

 10. Weld edge is the end surface of the part after machining to the severing weld dimensions given by the design documents.

11. A roll is a defect in the form of metal accumulating in the welding process (weld overlay) on the base metal surface but not fused together with it.

12. Lack of penetration is a lack of fusion in the welded joint or deposited part between the base metal and seam metal (deposited metal) or between individual beads.

13. A discontinuity is a disruption of the material uniformity causing an abrupt change in one or more physical characteristics determined by non-destructive control. Discontinuity is a generalized name for cracks, delamination, burn-through, flaws, pores, lack of penetration and inclusions.

14. Nominal base metal thickness of the deposited part is the base metal thickness of the part specified in the design documents (without the consideration of tolerances).

15.1 The nominal thickness of the welded parts is the base metal thickness of parts in the area adjoining the weld seam specified in the design documents (without taking account of tolerances).

16. A delamination is a defect in the form of discontinuity of fusion of the deposited metal with the base metal on the parts (products) with the deposited anti-corrosive coating or pre-deposited edges, and on other deposited parts.

17. An undercut is a depression in the form of a groove at the boundary of weld seam surface with the base metal or at the boundary of surfaces of two adjacent beads.

18. Reduced area of inclusion or cluster (during radiographic examination) is the multiplication of the maximum size of inclusion (cluster) by its maximum width (specified for very small singular inclusions and singular clusters).

19. A burn is a defect in the form of through-hole in the weld seam formed following breakthrough of a part of the liquid metal puddle in the welding process.

20. Industrial reference welded joint is a welded joint made for conformance check of the metal characteristics of industrial welded joints to the established requirements.

21. Radiation thickness is the total length of sections of subject beam axis of the directed primary ionizing radiation in the material of monitored item.

Design throat thickness is the size h of the perpendicular specified in the design documents drawn from the connection points of the welded parts (point 0) to the straight line connecting the edge of its surface in one transverse direction (at convex fillet) or to the parallel tangent of the specified line to the weld seam surface (at concave fillet weld) (figure 1.3).

For the double-sided fillet weld its design height is determined as the sum of design heights (h1 + h2) of its parts executed from different sides.

Figure 1.3. Design throat thickness

23. Weld hole in the form of funnel-like or tubular cavity in the weld seam.

24. A cluster is two or several inclusions (pores, slag or tungsten inclusions) with the maximum size over 0.2 mm (figure 1.4 a) and the minimum distance between their edges less than the distance specified for singular inclusions, but not less than the maximum width of any two adjacent inclusions under consideration. When assessing the distances between the clusters and inclusions the cluster shall be considered as a singular inclusion.

Figure 1.4. Cluster

(A - maximum size of cluster;

B - maximum width of cluster);

3b₁> L_1-2 b₁ for b₁> b₂, or 3b₂> L_1-2 b₂

for b₂> b₁, or L_1-2< 3a₁ for a₁< a₂, or L_1-2< 3a₂

for a₂< a₁; 3b₁> L_1-3 b₁ for b₁> b₃, or 3b₃> L_1-3

 b₃ for b₃> b₁, or L_1-3< 3a₃ for a₃< a₁, or L_1-3<

3a₁ for a₁< a₃; 3b₂> L_2-3 b₂ for b₂> b₃, or 3b₃> L_2-3

 b₃ for b₃> b₂, or L_2-3< 3a₂ for a₂< a₃,

or L_2-3< 3a₃ for a₃< a₂

24.1. Cluster external outline is an outline limited by the outer edges of cluster inclusions and tangent lines connecting such edges (Figure 1.4 b).

24.2. Maximum size of singular inclusion A is the maximum distance between two adjoining points of the external cluster outline (figure 1.4 b).

24.3. Maximum width of the cluster B is the maximum distance between two points of the external cluster outline measured in the direction perpendicular to the maximum size of cluster (figure 1.4 b).

25. A singular cluster is a cluster with minimum distance L from its external outline to the external outline of any adjacent cluster or inclusion not less than a triple maximum width of the two clusters under consideration (or a cluster and an inclusion), but not less than a triple maximum cluster (inclusion) size of the smaller one (of the two elements under consideration) (Figure 1.5).

Figure 1.5. Singular clusters

26. A group of inclusions is a group consisting of two or several inclusions with the minimum distance between their edges less than the maximum width of at least one of the two adjacent inclusions under consideration; the external outline of the group of inclusions under consideration is limited by the outer edges of inclusions constituting the group and tangent lines connecting such edges (Figure 1.6).

Inadmissible inclusions and clusters are singular inclusions (clusters) exceeding the established norms by sizes, quantity or total reduced area.

Figure 1.6. Group of inclusions

(a - maximum size of the group of inclusions;

b - maximum width of the group of inclusions):

L_1-2< b₁ for b₁> b₂, or L_1-2< b₂ for b₂> b₁;

L_1-3< b₁ for b₁> b₃, or L_1-3< b₃ for b₃> b₁;

L_2-3< b₂ for b₂> b₃, or L_2-3< b₃ for b₃> b₂

27. The total reduced area of inclusions and clusters is the sum of reduced areas of singular inclusions and clusters.

28. A crack is a defect in the form of discontinuity of weld metal or deposited part (product).

29. Cavity between the beads is the longitudinal depression between two adjoining beads (assessed by the maximum depth).

30. A shrinkage cavity is a defect in the form of a cavity or depression which is formed on shrinkage of molten metal in the process of setting (located as a rule at the places, where welding is discontinued or terminated).

31. Ripple is transverse or round (during automatic submerged-arc welding - lobe) low spots on the bead surface formed following non-uniform solidification of the puddle metal (assessed by maximum depth).

32. Seam width is the distance between the weld seam surface edges in one transverse direction.

33. Equivalent discontinuity area (during ultrasonic testing) is the area of the flat bottom hole located at the same distance from the entry surface as the real discontinuity and creating a signal of the same amplitude.

Appendix 1
to the Federal rules and regulations
in the field of atomic
energy use "Regulations for Control of Metal
of Equipment and Pipelines of
Nuclear Power Installations
at Manufacture and Assembly"
approved by Decree of the Federal
Environmental,
Industrial and Nuclear Supervision Service
dated 14.11.2018. No. 553

TESTING OF
WELDED JOINTS FOR WELDING OF TUBES INTO TUBE PLATES

AND TUBE HEADERS

1. The methods and scope of non-destructive testing of welded joints for welding of steel tubes into tube plates and tube headers of equipment are given in the table N 2.1 of this Appendix. The welded joints have been executed by electric-arc welding.

Table No. 2.1

2. Radiographic examination in accordance with the table N 2.1 of this Appendix is made on the welded joints with minimum depth of weld penetration (from the pipe wall or header mirror) at least 2.5 mm.

3. Tightness control is performed by helium leak detectors.

4. During welding of steel tubes by manual arc welding metallographic studies of reference welded joints are performed at the beginning of each shift. Sampling is made from at least four sections of each reference welded joint. When using automated welding the scope of metallographinc studies is established by the design and process documents.

5. The methods and scope of non-destructive testing of welded joints for welding of titanium alloy steel tubes into tube plates and tube headers of equipment are given in the table 2.2 of this Appendix.

Table 2.2

6. Radiographic examination in accordance with the table 2.2 of this Appendix is made on the welded joints with minimum depth of weld penetration (from the pipe wall or header mirror) at least 2.5 mm and pipe inner diameter at least 15.0 mm.

7. The scope of metallographic studies of welded joints of welding titanium alloy tubes into tube plates and into headers is established by the design and process documents.

8. The depth of penetration value is established in the design documents.

9. The reference welded joints specified in the items 4 and 7 of this Appendix shall be performed by the same welder, on the same equipment and on the same conditions as the industrial welded joints for welding tubes into tube plates and headers.

10. The quantity of reference welded joints shall constitute:

a) one for each 100 welded joints at number of joints in the tube plate more than 500;

b) one for each 50 welded joints at number of joints in the tube plate less than 500.

Appendix 3
to the Federal rules and regulations
in the field of atomic
energy use "Rules of control of
equipment and pipelines metal of
nuclear power installations
during manufacture and installation"
approved by Decree of the Federal 
Service for Environmental,
Industrial and Nuclear Supervision
dated 14.11.2018. No. 553

NON-DESTRUCTIVE TESTING
OF DEPOSITED SEALING AND GUIDING SURFACES

1. Weld overlay control of sealing and guiding surfaces shall be made before and after machining.

Visual and measuring control should be made before machining.

After machining the deposited surfaces shall be subject to:

a) Visual inspection on all deposited surfaces over the entire area including the lateral surfaces of the weld junction with the base metal;

b) Capillary control on all the deposited sealing working surfaces over the entire area including the lateral surfaces of the weld junction with the base metal;

c) Measurement control and measurement of hardness in accordance with the process documentation.

Visual and dimensional inspection

2. Round singular inclusions, the sizes and quantity thereof exceed those given in the table 3.1 of this Appendix shall not be allowed on the sealing surfaces. The round singular inclusions with maximum size above 0.2 mm shall be subject to documentation. The inclusions with maximum size up to 0.2 mm inclusive shall be excluded.

The inclusions subject to documentation shall not be allowed (independent of the sizes and their quantity), if:

a) they are located at a distance of less than 2.5 mm from the boundaries of the working surfaces;

b) at least two inclusions are located on one radial line (at annular seal) or on one generatrix (at cone seal).

Table 3.1

3. Round singular inclusions with maximum size above 1.5 mm, and round singular inclusions with maximum size above 0.2 to 1.5 mm inclusive shall not be allowed on the guiding surfaces at their quantity more than four for any 20.0 cm² of deposited surface.

4. The quantity limits of allowed inclusions shall be proportionately changed for the  sealing and lateral deposited surfaces adjoining them, not a multiple of 100.0 mm. The fractional quantity of permitted inclusions shall be rounded to the nearest whole number.

The quantity standards of allowed inclusions shall be proportionately changed for the generatrix and lateral deposited surfaces adjoining them, not a multiple of 20.0 cm². The fractional quantity of permitted inclusions shall be rounded to the nearest whole number.

Liquid penetrant test

5. The quality assessment of weld deposit surfaces during liquid penetrant test may be performed both by indications and actual characteristics of the revealed discontinuity flaws after removal of the developer in the area of recorded indications.

6. The indication control results shall be considered as satisfactory at simultaneous meeting of the following conditions:

a) all indications are round, there are no linear indications;

b) maximum size of each indication does not exceed by more than three times the values given in the items 3, 4, 5 of this Appendix for singular inclusions;

c) number of indications does not exceed the standards given in the items 3, 5 of this Appendix for singular inclusions.

d) indications are singular (minimum distance between the edges of any two round indications is less than the maximum size of the greater of the two considered indications).

The round indications with maximum size up to 0.6 mm inclusive are excluded.

The discontinuities not meeting the standards of this item shall be subject to actual performance control given in the items 3, 4 of this Appendix. The control results are final.

Hardness measurement

7. Hardness of deposited surfaces after heat treatment shall conform to the values given in the tabl2 5, 6 of Appendix 5 to these Regulations.

8. The upper acceptable hardness limit is established by the design and process documents depending on the scope of weld deposit and heat treatment regimes.

9. The deviation of hardness values of two-layer weld overlays from the values given in the table 5.6 of Appendix 5 to these Regulations by maximum 8%.

10. The minimum number of measurements shall be at least:

a) two - for valves with nominal diameter up to 65.0 mm inclusive;

b) three - for valves with  nominal diameter more than 65.0 to 150.0 mm inclusive;

c) five -f or valves with nominal diameter more than 150.0 to 400.0 mm inclusive;

d) eight - for valves with nominal diameter more than 400.0 to 600.0 mm inclusive;

e) ten - for valves with nominal diameter more than 600.0 mm.

11. The performance of repeat measurements with double the number of measurements shall be allowed if the results of hardness measurement of deposited surfaces are not satisfactory. The results of repeated tests shall be definitive.

12. The testing shall be made directly on the working surfaces of the weld deposit on the parts with deposited surfaces accessible for hardness measurements after preliminary machining with allowance for machining maximum 0.5 mm

13. The test shall be made on reference specimen on the parts with deposited surfaces inaccessible for hardness measurement identical to the tested industrial deposited parts for the base metal grade, preparation for weld overlay, method of deposition, lot of surfacing materials, deposition technology, heat treatment and machining.

Quality control of weld overlay of sealing surfaces of
titanium alloy valve parts

14. Geometrical dimensions of the weld overlay shall be subject to inspection directly after the weld overlay before the heat treatment.

15. Visual inspection shall be made after weld overlay and machining for revealing the pores and tungsten inclusions on the surface of weld deposit and cracks on the surface of the weld deposit and in the heat affected area.

Cracks shall not be allowed on the weld deposit and in the heat affected area. Tungsten inclusions and pores with their dimensions and quantity exceeding the values given in the table 3.2 of this Appendix shall not be allowed on the finished surface.

Table  3.2

16. Liquid penetrant test shall be performed after the preliminary and after final machining with the purpose of revealing the cracks and pores not detected during visual inspection.

17. Hardness measurements of the weld deposit shall be performed directly on the sealing surface after preliminary machining. The plane on which hardness is measured shall have allowance 1.5 - 2.0 mm. It shall be allowed to measure hardness of the weld deposit on the samples deposited together with the standard products of the same lot of welding consumables, on the same regimes and on the same equipment. The measurements shall be made on machined surfaces at weld deposit height at least 4.0 mm. Hardness of weld deposit shall constitute 350 - 430 HV. The number of hardness measurements shall be at least ten. Maximum three rejections from ten measurements shall be allowed. At large number of rejections the number of measurements shall be double, but maximum six rejections shall be allowed. The hardness measurement results on double the number of samples are final.

Appendix 4
to the Federal rules and regulations
in the field of atomic
energy use "Rules of control of
equipment and pipelines metal of
nuclear power installations
during manufacture and installation"
approved by Decree of the Federal 
Service for Environmental,
Industrial and Nuclear Supervision
dated 14.11.2018. No. 553

QUALITY
ASSESSMENT BASED ON NON-DESTRUCTIVE TESTING OF WELDED
JOINTS AND DEPOSITED SURFACES

Visual and dimensional inspection

1. The limits of admissible singular surface inclusions for welded joints and pre-deposited edges of the steel and iron-nickel alloy parts are given in the table 4.1 of this Appendix.

Table 4.1

2. The height (depth) of recess limits between the beads and ripples of their surface for the welded joints of steel and iron-nickel parts are given in the table 4.2 of this Appendix.

Table  4.2

3. Singular inclusions of size maximum 1.0 mm shall be allowed on the surfaces of anti-corrosive cladding if their number at any section of size 100.0x100.0 mm does not exceed four.

4. When performing visual inspection of anti-corrosive cladding the inclusions with the largest actual size up to 0.2 mm shall not be taken into account.

On the surfaces of corrosion-resistant cladding, the height (depth) of the recess between the beads should not exceed 1.0 mm, and ripple - 0.5 mm.

During automatic arc welding with tape on the surfaces of corrosion-resistant cladding a discrepancy shall be allowed between the heights of two adjacent beads at the places of their conjugation to an amount not exceeding 2.0 mm.

5. The forms and dimensions of the design elements of completed welds (width and height of weld reinforcement, minimum distance from the edge of weld reinforcement to the fusion line of the preliminary weld overlay with the base metal) shall meet the requirements of the federal standards and rules in the field of atomic energy use regulating the welding and weld overlay of equipment and pipelines of nuclear power generating facilities.

6. Continuous or intermittent root concavity on the inside shall be allowed  at swivel joint welding of steel tubular parts without backing rings. Their dimensions shall not exceed the values given in the table 4.3 of this Appendix.

Table 4.3

7. Root concavity on the inside shall be allowed  at one-directional welding of steel tubular parts without backing rings. Their dimensions shall not exceed the values given in the table 4.4 of this Appendix.

Table  4.4

8. The dimensions of continuous or intermittent root convexity in case of one-side steel pipe welding without backing rings shall meet the standards given in the table 4.5 of this Appendix.

Table  4.5

9. Admissible low spots between the beads shall not be taken into account during measurements of the anti-corrosive cladding or preliminary cladding on the edges of parts.

10. The standards of admissible singular surface inclusions and deviations from the geometrical dimensions of welded joints of the aluminum alloy parts and assembly units are given in the table 4.6 of this Appendix.

Table 4.6

11. The quality rating standards of class I - III welded joints of titanium alloy parts and assembly units following visual and dimensional inspection are given in the table 4.7 of this Appendix.

Table  4.7

12. The discontinuities found during visual and dimensional inspection with their sizes exceeding the permitted shall be eliminated before inspection by other methods.

Control using a metal reference gauge (a ball)

13. The results of control using  metal reference gauge (a ball) shall be considered as satisfactory if the reference gauge (ball) of given diameter by the design document passes through the inspected weld joint.

Leakage monitoring

14. The weld joint quality is considered as satisfactory if leak-in or leakage shall not be found in the test process exceeding the relevant indices for the leakage class established by the design documents.

Liquid penetrant test

15. The quality assessment of welded joints and weld deposit surfaces during liquid penetrant test may be performed both by indications and actual characteristics of the revealed discontinuity flaws after removal of the developer in the area of recorded indications.

16. In case of indicator penetrant test, the quality of welded joint or deposited surface shall be considered satisfactory in case of simultaneous observation of the following conditions:

a) indications are isolated;

b) no linear indications;

c) maximum size of each indication does not exceed by more than three times the values given in the items 2 and 3 of this Appendix for single inclusions;

d) number of indications does not exceed the values given in the items 2 and 3 of this Appendix for single inclusions.

17. The indications are considered as isolated if the minimum distance from the edge of each of them to the edge of any other adjacent indication is not less than the maximum size of the indication with lesser value of this attribute.

18. Rounded traces with the largest dimension of up to 0.6 mm are not considered regardless of the nominal thickness of the welded (surfaced) parts.

19. The discontinuities not meeting the requirements of item 18 of this Appendix is allowed to subject for actual characteristics inspection and its results are final.

20. Quality assessment of the welded joint and deposited surface during liquid penetrant test for actual characteristics of the revealed discontinuities shall be made in compliance with the requirements of items 1, 2 and 4 of this Appendix.

Magnetic-particle test

21. Quality assessment of magnetic particle test shall be made in compliance with the requirements established for visual inspection in the items 1, 2 of this Appendix. It shall be allowed to assess the exposed discontinuity flaws by their actual characteristics after removal of the deeveloper or powder.

22. It is allowed to perform liquid penetrant test of the relevant areas if inadmissible indications are revealed. The metal shall be polished at positive results of inspection to a depth of up to 1.0 mm (on condition of ensuring minimum metal thickness limit) and subsequent repeat magnetic particle test, the results therein being final.

Radiographic examination

23. The quality of welded joint (or deposited surface) of the parts and assembly units shall be considered as satisfactory if cracks, lack of penetration as well as the inclusions, root concavity or convexity are not found during inspection.

24. If the concavity or excess root fusion are checked at measurement control, they shall not be assessed during radiographic examination.

25. The standards of admissible singular inclusions and clusters for the welded joints (except classes Iн and IIн) of the steel parts and assembly units are given in the table 4.8 of this Appendix.

Table 4.8

26. The required sensitivity is given in the table 4.8 for step wedges. When using wire penetrameters, the sensitivity values 0.30; 0.60; 0.75 and 1.5 mm may be replaced by the values 0.32; 0.63; 0.80 and 1.6 mm respectively.

27. The standards of admissible singular inclusions and clusters for the welded joints of classes Iн and IIн of the parts and assembly units made of steel are given in the table 4.9 of this Appendix.

Table 4.9

28. The inclusions with their maximum size less than the values specified in the column "required sensitivity" of the tables 4.8, 4.9 of this Appendix shall not be considered when calculating the number of inclusions and their aggregate reduced area and when considering the distances between the inclusions (clusters).

Any inclusions with the ir maximum size over 0.2 mm are considered when identifying the clusters.

The limits of admissible singular inclusions at nominal wall thickness of welded parts less than1.0 mm are established by the design documents; the standards shall not exceed the values given in the tables 4.8, 4.9 of this Appendix for thickness 1.0 mm.

29. Any combination of inclusions (singular clusters, groups of inclusions), which may be inscribed in a rectangle with side dimensions not exceeding the values of the maximum dimension limit and maximum width limit of a large singular inclusion should be considered as one continuous inclusion.

30. Any combination of inclusions (singular cluster, groups of inclusions) which can be inscribed in a square with the side not exceeding the value of the maximum dimension limit of a singular inclusion should be considered as a continuous inclusion.

31. Singular inclusions and (or) singular clusters of admissible dimensions without taking account during calculation of the aggregate area of singular inclusions and singular clusters in the relevant quantity may be allowed if large singular inclusions are not available or if their number is less than the limits given in the table 4.8 of this Appendix.

32. For welded joints (deposited edges) with a length of less than 100 mm, the limits listed in tables 4.8, 4.9 of this Appendix shall be proportionally reduced in number and total area of inclusions (clusters). The fractional quantity of permitted inclusions (clusters) shall be rounded to the nearest whole number.

33. The required sensitivity of inspection and admissible maximum dimensions of singular inclusions and clusters shall be taken as per standards given in the table 4.8, 4.9 of this Appendix at inspection of the pre-deposited edges. The admissible number and aggregate reduced area of singular inclusions and clusters shall not exceed 50% of the values given in the table 4.8, 4.9 of this Appendix.

34. The design clearance spaces visible in the radiograph including the clearance spaces filled with poured slag or metal are not a rejection criterion during inspection of welded joints with lack of penetration or with backup rings, or on "whiskers".

35. The limits of admissible singular inclusions and clusters for the welded joints of classes I, II and III of the  aluminum alloy parts and assembly units are given in the table 4.10 of this Appendix.

Table 4.10

36. The quality standards assessment of welded joints of titanium allow parts and assembly units are given in the table 4.11 of this Appendix.

Table 4.11

Ultrasonic inspection

37. The limits of admissible singular discontinuities at ultrasonic inspection of the butt weld joints of perlitic grade steel and (or) high-chrome steel parts and assembly units with thickness from 2.0 to 5.5 mm are given in the table 4.12 of this Appendix.

Table  4.12

38. The limits of admissible singular discontinuities at ultrasonic inspection of the butt weld joints of perlitic grade steel and (or) high-chrome steel parts and assembly units with thickness more than 5.5 mm are given in the table 4.13 of this Appendix.

Table 4.13

The pre-deposited edges using high-chrome welding materials shall be tested as part of the ready welded joint as per quality assessment standards given in the table 4.13 of this Appendix without division into pre-deposit and seam metal. The use of a reference notch-type standard reflector and application of the limits of admissible singular discontinuities given in the table 4.13 of this Appendix shall be allowed during inspection of welded joints of tubes with nominal wall thickness up to 50.0 mm.

39. The limits of admissible singular discontinuities in the deposited metal fusion zone with base metal during inspection of overlay with austenitic welding materials of the edges of perlitic class steel or high-chrome steel are given in the table 4.14 of this Appendix.

Table 4.14

40. The limits of admissible discontinuities in the fusion zone of deposited metal with the base metal during inspection of anti-corrosive weld overlay are given in the table 4.15 of this Appendix.

Table 4.15

41. Ultrasonic inspection of the sub-surfacing zone of width at least 10.0 mm for the purpose of revealing the sub-surfacing cracks shall be made on demand by the design documents for parts made of steel grades 10GN2MFA, 12Kh2MFA, 12Kh2MFA-A, 15Kh2MFA, 15Kh2MFA-A, 15Kh2MFA mod. A, 15Kh2MFA-A mod. A, 15Kh2MFA mod. B, 15Kh2NMFA, 15Kh2NMFA-A, 15Kh2NMFA class 1, 15Kh3NMFA, 15Kh3NMFA-A, 15Kh2NM1FA, 15Kh2NM1FA-A with anti-corrosive cladding. The rejectable inspection sensitivity level shall be established according to the table 4.16 of this Appendix.

The quality of sub-surfacing zone shall be considered as satisfactory if long discontinuities with signal amplitude exceedign the rejection level are not revealed.

Table 4.16

42. The quality assessment standards following ultrasonic testing of welded joints of aluminum alloy parts and assembly units are given in the table 4.17 of this Appendix.

Table 4.17

43. The admissible values of equivalent area of discontinuities of the  welded joints of titanium alloy parts and assembly units are given in the table 4.18 of this Appendix.

Table 4.18

44. The admissible values of the length of discontinuities of the  welded joints of titanium alloy parts and assembly units are given in the table 4.19 of this Appendix.

Table 4.19

45. The admissible number of discontinuities at  admissible values of equivalent area and length of the  welded joints of titanium alloy parts and assembly units are given in the table 4.20 of this Appendix.

Table 4.20

46. The quality of welded joint, surfacing of edges for welding and anti-corrosive clading shall be considered as satisfactory on simultaneous meeting of the following requirements:

a) characteristics and number of discontinuities meet the admissible values for welded joints given in the tables 4.12 - 4.16 of this Appendix;

b) the distance along the scanning surface between two adjacent discontinuities is not less than the conditional length of the larger discontinuity;

c) no two-dimensional discontinuities like cracks and lack of penetration.

Hardness control

47. The weld deposit hardness of sealing surfaces of the parts shall conform to the requirements of Appendix 3 to these Regulations.

Appendix No. 5
to the Federal rules and regulations in
the field of atomic energy use
"Regulations for Control of Metal of
Equipment and Pipelines of Nuclear
Power Installations at
Manufacture and Assembly"
approved by Decree of the Federal
Environmental, Industrial and
Nuclear Supervision Service
dated November 14, 2018 No. 553

CHEMISTRY OF WELD DEPOSIT (SEAM METAL)

1. Chemistry shall be determined in compliance with the requirements of standardization documents included in the Summary list.

2. Samples for determination of the seam metal chemistry shall be taken in the test weld area of divided from the base metal by at least two beads or from two upper layers of extra four-layer weld overlay made on one of the end sections of the test weld surface. Samples shall be taken pursuant to the standardization document included in the Consolidated list.

Samples for determination of the electroslag weld seam metal chemistry shall be taken in compliance with the process documentation.

3. Results of chemistry control of weld deposit (seam metal) are deemed satisfactory if chemical parameters of samples comply with the tables of this appendix.

Standard designations of chemical elements are used in the tables of this appendix.

4. The content of chemical elements in weld deposit (seam metal) for automatic submerged welding and wire weld overlaying is specified in Table No. 5.1 of this appendix.

Table No. 5.1