GOST 20700-75 Bolts, Studs, Nuts and Washers for Flanged and Anchor Connections, Plugs and Clamps with Medium Temperature from 0 to 650 °C.

BOLTS, STUDS, NUTS AND WASHERS

FOR FLANGED AND ANCHOR CONNECTIONS, PLUGS AND

CLAMPS WITH MEDIUM TEMPERATURE FROM 0 TO 650°C

Technical specifications

GOST 20700-75*

(ST SEV 1066-78)

State Standard of the Union of Soviet Socialist Republics

Bolts, Studs, Nuts and Washers for Flanged and Anchor Connections, Threaded Plugs and Clamps with Medium Temperature from 0 to 650°C. Specifications Bolts, studs, nuts and washers for flanged and anchor connections, corks and yokes with medium temperature from 0 to 650°C. Specifications	GOST 20700-75* (ST SEV 1066-78)

By Resolution of the USSR State Committee for Standards of the Council of Ministers dated March 28, 1975, No. 794, the effective date was established

as of 01.01.76

Reviewed in 1985. By Resolution of Gosstandart dated 27.12.85 No. 4667, the validity period was extended

to 01.01.96

Non-compliance with the standard is punishable by law

This standard applies to bolts, studs, nuts and washers for flanged and anchor connections of steam boilers, pipelines and connecting parts, steam and gas turbines, valves, instruments, apparatus and tanks, plugs for turbines and pipelines, round-section clamps for pipeline supports and hangers with a medium temperature from 0 to 650°C, and hot-water boilers with water temperature above 115°C.

This standard does not apply to flanged connections of facilities under the jurisdiction of the USSR Gosgortekhnadzor with a nominal pressure of less than 0.07 MPa (0.7 kgf/cm²).

This standard fully complies with ST SEV 1066-85.

(Amended edition, Amendments No. 1, 2, 3).

1. TECHNICAL REQUIREMENTS

1.1. Bolts, studs, nuts, plugs, clamps and washers (hereinafter referred to as fasteners) are manufactured in accordance with GOST 9064-75, GOST 9065-75, GOST 9066-75 or working drawings, from steel grades specified in Table 1.

(Revised edition, Amendment No. 2).

1.2. The conditions of use for the steel grades specified in Table 1, in terms of medium temperature and pressure, for bolts, studs and nuts of flanged connections of facilities under the jurisdiction of the USSR Gosgortekhnadzor, must comply with the “Rules for the Design and Safe Operation of Steam and Hot-Water Boilers” (approved August 30, 1966), the “Rules for the Design and Safe Operation of Steam and Hot-Water Pipelines” (approved March 10, 1970), and the “Rules for the Design and Safe Operation of Pressure Vessels” (approved May 19, 1970).

(Amended edition, Amendment No. 1).

1.3. For the manufacture of fastener components, steels melted in open-hearth furnaces, electric furnaces, by electroslag or vacuum-arc remelting, or by other processes of at least equivalent quality, are used. The use of rimmed, semi-killed, Bessemer and free-cutting steel for fasteners is not permitted.

(New edition, Amendment No. 3).

1.4. Materials for manufacturing fastener components are selected depending on the design metal temperature and are divided by quality into:

category I — carbon steels meeting technical requirements for general-purpose products of product grade B with a nominal thread diameter up to 48 mm and a design product metal temperature up to 200°C;

category II — carbon steels used for bolts, studs, plugs, clamps and nuts of product grade A with a nominal thread diameter up to 48 mm, and washers of all sizes, with a design product metal temperature up to 300°C. Carbon steel of ordinary quality per GOST 380-71, supplied with impact toughness testing after mechanical aging, for products of increased precision with limiting parameters per Table 1;

category III — high-quality carbon steels in the improved (quenched and tempered) condition, used for bolts, studs, plugs, clamps and nuts of all sizes with an operating temperature up to 400°C, provided the tempering temperature exceeds this temperature by at least 100°C. The use of category III steels up to a design metal temperature of 425°C is permitted if long-term strength data at the corresponding design temperature are available.

category IV — heat-resistant and high-temperature alloy steels in the heat-treated condition, used for fasteners of all sizes with an operating temperature not exceeding the medium temperature (Table 1 and clause 1.2), provided the tempering temperature exceeds this temperature by at least 100°C, and the final aging step for alloys exceeds this temperature by at least 50°C.

(Amended edition, Amendment No. 3).

1.4.1. Blanks for bolts, studs, nuts, plugs and clamps of all quality categories are subjected to final heat treatment after cold and hot deformation. Heat treatment is not required after thread rolling.

(Added, Amendment No. 3).

1.5. Steel grades of categories II–IV are subjected to full visual inspection and sample incoming inspection for hardness and macrostructure by the fastener manufacturer. The scope of hardness inspection is not less than 2% of the batch of blanks.

Macrostructure inspection is performed on two templates from the batch, only for alloy steel grades. The steel macrostructure and hardness in the initial condition must comply with the material supply standards.

If hardness inspection results are unsatisfactory, category III and IV steels are subjected to high tempering or annealing. Recommended high-tempering or annealing regimes and hardness values are given in Annex 5.

Additional chemical analysis of blank material may be performed by the fastener manufacturer.

Additional full-scale ultrasonic testing (UT) of blanks is permitted.

(Amended edition, Amendment No. 3).

1.6. Depending on the purpose and operating conditions of the fastener components, five quality groups of finished products are established, specified in Table 2.

1.7. For bolts, studs and nuts made of category I and II steel, property classes, mechanical properties, and stresses from proof and test loads are per GOST 1759-70.

Bolts, studs, nuts, plugs and clamps made of category I and II steel may be manufactured with mechanical properties or hardness per GOST 380-71, GOST 1050-74, GOST 1051-73, GOST 10702-78.

1.8. When manufacturing nuts of quality groups 1 and 2, the mechanical property requirements are established by agreement between the manufacturer and the customer.

For fasteners made of category III and IV steel, the heat treatment regimes for blanks, the mechanical property requirements on longitudinal specimens at normal (20°C) temperature, and hardness for bolts, studs, plugs and clamps of quality groups 1, 2, 3 and 4, and for nuts of quality groups 3 and 4, must comply with those specified in Table 3.

For washers, hardness requirements are established in accordance with the standards for the steel grades specified in Table 1.

Heat treatment of bent clamps in the finished condition is permitted, provided the thread is protected from oxidation.

1.9. Fasteners with an operating temperature up to 200°C may be manufactured with a coating. The type, thickness and designation of coatings are per GOST 1759-70.

For fasteners with a metal operating temperature above 200°C, coatings that do not reduce the strength and functionality of the joints are used.

1.4–1.9 (Amended edition, Amendments No. 1, 2).

1.10. Protective coatings must be uniform; blisters and peeling are not permitted.

1.11. Requirements for the depth of the decarburized layer for fasteners made of category I and II steel with nominal thread diameters up to 48 mm are per GOST 1759-70. A decarburized layer is not permitted for bolts, studs, and the threaded surface of nuts, and for clamps machined in the finished condition, for diameters over 12 mm made of category III and IV steel.

(Revised edition, Amendments No. 1, 2).

1.12. When selecting steel grades for fastener components depending on the quality category, the following mechanical property characteristics are used in strength calculations of fasteners:

for fastener components made of category I and II steel — mechanical properties or hardness at 20°C per GOST 1759-70 or GOST 380-71, GOST 1050-74, GOST 1051-73 and GOST 10702-78;

for fastener components made of category III steel — mechanical properties and hardness per Table 3. Guaranteed yield strength values at 350°C are per GOST 23304-78;

for fastener components made of category IV steel — mechanical properties and hardness per Table 3, with guaranteed long-term strength and creep limit values ensured at the level of agreed requirements by observing the heat treatment regime and the level of mechanical properties per Table 3.

Long-term strength and creep limit requirements are established by agreement of the parties. Average values of long-term strength and creep limit for category IV steels are given in reference Annexes 1 and 1a.

1.13. Average values of the modulus of elasticity, coefficients of linear expansion, and relaxation resistance (residual stress) of steels are given in reference Annexes 2–4.

1.12–1.13 (New edition, Amendment No. 3).

Table 1

Steel grade	Standard designation	Limiting parameters
		Bolts, studs, plugs and clamps		Nuts		Washers
		Medium temperature, °C	Nominal pressure Py, MPa (kgf/cm²)	Medium temperature, °C	Nominal pressure Py, MPa (kgf/cm²)	Medium temperature, °C	Nominal pressure Py, MPa (kgf/cm²)
VSt3sp3	GOST 380-71	-	-	-	-	Up to 350	10(100)
VSt3sp5 VSt4sp3 VSt4sp5 VSt5sp2 VSt5sp5		Up to 350	1.6(16)	Up to 350	2.5(25)
		-	2.5(25)	-	-
10	GOST 1050-74	-	-	Up to 350	2.5(25)	Up to 450
20		Up to 400	1.6(16)	Up to 400	10(100)
25 30, 35, 40 45	GOST 1050-74 GOST 10702-78					-	-
		Up to 425	10(100)	Up to 425	20(200)	Up to 450	Not limited
35Kh, 40Kh	GOST 10702-78		20(200)	Up to 450	20(200)	-	-
30KhMA, 35KhM	GOST 4543-71	Up to 450	Not limited	Up to 510	Not limited	-	-
20×13 (2×13)	GOST 18968-73					Up to 450	Not limited
15KhM	GOST 4543-71	-	-	-	-	Up to 545
25Kh1MF (EI10)	GOST 20072-74	Up to 510	Not limited	Up to 540	Not limited	-	-
13Kh11N2V2MF (EI961)	GOST 5949-75
25Kh2M1F (EI723)	GOST 20072-74	Up to 535		Up to 565		-	-
15Kh11MF (1Kh1 1MF) 20Kh12VNMF (EP428) 18Kh11MNFB (EP291)	GOST 18968-73	Up to 560		Up to 560		Up to 580	Not limited
18×12VMBFR (EI993)	GOST 5949-75
12×1MF (12KhMF)	GOST 20072-74	-	-	-	-	Up to 570	Not limited
20×1M1F1TR (EP182) 20×1M1F1BR (EP44)		Up to 580	Not limited	Up to 580	Not limited	-	-
08×16N131M2B (EI680)	-	Up to 625		Up to 625		Up to 650	Not limited
31×19N9MVBT (EI572)	GOST 5949-75					-	-
KhN35VT (EI612)	-	Up to 650		Up to 650		-	-
10×11N22T3MR (EI696M)	-
12×1.8N10T (Kh18N10T) 08×18N10T (0Kh18N10T)	GOST 5949-75	-	-	-	-	Up to 650	Not limited
Notes: 1. By agreement between the customer and the manufacturer, fasteners may be manufactured from other steel grades, provided they meet the requirements of this standard. 2. The limiting metal temperatures for fasteners are as per clause 1.4. 3. Nuts and washers may be manufactured from calibrated steel per GOST 1051-73 and GOST 20072-74, and washers from sheet steel per approved regulatory and technical documentation, provided the technical requirements of this standard are met. 4. Steel grade 25×2M1F (EI 723) may be used until January 1, 1988.

Table 2

Quality group of finished products and blanks	Test type	Number of items per batch	List of acceptance characteristics
1	Determination of mechanical properties	100%	Values of yield strength σ0.2, cross-sectional reduction y, impact toughness KCU (an) and hardness HB
	Hardness determination	100%
2	Determination of mechanical properties	2%, but not less than 2 pcs.	Values of yield strength σ0.2, cross-sectional reduction y and impact toughness KCU (an)
	Hardness determination	100%
3	Hardness determination	100%	Hardness value HB
4	Hardness determination	2%, but not less than 2 pcs.	Hardness value HB
5	No testing	-	-
Notes: 1. When determining mechanical properties under group 2, blanks with the extreme hardness values are selected. For group 2 items subjected to thermochemical treatment, blanks with hardness within the range of the steel grade for the given property class may be selected. 2. Only quality groups 3, 4 and 5 are established for washers. 3. Quality group 1 is assigned by the designer for fasteners with special technical requirements. The use of quality group 5 is not permitted for bolts, studs and nuts of flanged joints, plugs and clamps under the jurisdiction of Gosgortekhnadzor of the USSR. 4. It is permitted to select 2 items or blanks per batch for determining mechanical properties under group 2 for fasteners with a thread diameter up to 24 mm. 5. The test types and list of acceptance characteristics for category I carbon steels and category II ordinary-quality carbon steels are as per the standards for metal products. 6. By agreement between the customer and the manufacturer, ultrasonic testing (UZK) of blanks after final heat treatment, or of finished products, is performed for items of quality groups 1–3. 7. The quality group is assigned by the designer and must be indicated in the product’s working drawing.

1.14. The surface roughness of fasteners intended for coating shall comply with GOST 9.301-78.

(Revised edition, Amendment No. 2).

1.15. Fasteners shall have metric thread per GOST 24705-81, produced by cutting or rolling. When preparing the shank for thread rolling, a smooth tapered section between the end of the thread runout and the unthreaded part of the shank, with a length not exceeding two thread pitches, is permitted.

When bolts, studs and nuts, plugs and clamps are made of steels 31×19N9MVBT (EI572), KhN35VT (EI612), 08×16N13M2B (EI680) at a metal operating temperature above 500°C, thread rolling is not permitted.

(Amended edition, Amendments No. 1, 2, 3).

1.15.1. The thread diameter of bolts, studs and nuts for pressure vessels shall comply with GOST 12.2.073-82; for other fasteners, it shall be not less than M12.

1.15.2. Stud types for flanged products shall be per GOST 9066-75.

1.15.1; 1.15.2 (Added additionally, Amendment No. 3).

1.16. The dimensions of thread runouts and incomplete threads shall be per GOST 10549-80; chamfers for parts with a thread diameter up to 24 mm shall be per GOST 12414-66; for a thread diameter above 24 mm, the chamfer width shall be within 0.7–2 thread pitches.

When using the rolling method, threads may be made without an end chamfer, provided that the concavity (recess) of the bearing surfaces does not exceed half the tolerance on head height or nut height, and not more than 1.5 thread pitches.

(Revised edition, Amendment No. 2).

1.17. Deviations in shape and location of surfaces and visual defects of bolts, studs, nuts, plugs and clamps with a thread diameter up to 48 mm made of category I steel shall comply with product grade B, and those made of category II–IV steel — with product grade A, per GOST 1759-70; for bolts and nuts, plugs and clamps with a thread diameter above 48 mm — product grade A per GOST 18126-72.

The deviation from perpendicularity of the bearing plane and the thread axis of type A nuts with a diameter up to 48 mm made of category II–IV steel shall not exceed 30, and for a diameter above 52 mm — per accuracy grade 12 of GOST 24643-81.

The deviation from perpendicularity of the bearing plane and the thread axis of type B nuts with a diameter up to 42 mm shall be per accuracy grade 11, and for a diameter above 48 mm — per accuracy grade 10 of GOST 24643-81.

The deviation from flatness of washers shall not exceed the tolerance on washer thickness.

The deviation from perpendicularity of the side surfaces of washers to the bearing surfaces shall not exceed 3°.

For studs with a nominal thread diameter above 48 mm, the following are not permitted:

an oblique cut of the shank for type A and type B studs within 0.7–2 thread pitches;

scores and tool marks that take the dimensions of the product beyond the limit deviations;

a reduction in thread profile height with a decrease in its outer diameter over more than two end threads;

rounding of the crest of the rolled thread profile that takes the thread outer diameter beyond the limit deviations;

displacement of the thread axis relative to the smooth part of the shank exceeding IT12 (the basic size for calculating the tolerance is the thread outer diameter).

Table 3

Steel grade	Heat treatment, °C				Diameter (thickness) of blank, mm		Strength category		Bolts, studs, plugs and clamps								Nuts
	quenching (Q) normalizing (N) austenitizing (A)		tempering						yield strength σ0.2, (kgf/mm²)	Ultimate tensile strength σv, MPa (kgf/mm²)	elongation δ, %	cross-sectional reduction ψ, %	impact toughness KCU (an), kJ/m² (kgf·m/cm²)	hardness number HB	indentation diameter, mm		hardness number HB, max	indentation diameter, mm
									min
Category III. Carbon steels
20	-		-		-		-		-	-	-	-	-	-	-		Per GOST 1050-74
25	N. 870–890		620-680		-		-		-	-	-	-	-				143	Over 5.0
30	N. 860–890				-		-		-	-							149	Over 4.9
35	N. 850–880		600-680		Up to 60		28		274 (28)	530 (54)	20	40	490 (5.0)	156…207	4.8-4.2		149	Over 4.9
					Over 60 to 100								441 (4.5)
					Over 100 to 300						17	38	343 (3.5)
40	N. 850–890 or Q. 840–860, water or oil				Up to 60		30		294 (30)	549 (56)	18	40	490 (5.0)	163…197	4.7-4.3		156	Over 4.8
					Over 60 to 100								392 (4.0)
					Over 100 to 300						16	37	343 (3.5)
45	N. 830–870 or Q. 830–870, water or oil				Up to 60		32		314 (32)	578 (58)	17	38	490 (5.0)	167…217	4.65-4.1		163	Over 4.7
					Over 60 to 100								392 (4.0)
					Over 100 to 300						14	35	343 (3.5)
Category IV. Alloy steels
35Kh, 40Kh	Q. 840–870, oil	500–620, water or oil			Up to 100	60		588-735 (60-75)		735 (75)	14	45	588 (6.0)	235…285	3.95-3.6		217…187		4.1-4.4
					Over 100 to 300						13	40	490 (5.0)
30KhMA	Q. 870–800, water or oil	540-620			Up to 100	65		637 784 (65-80)		784 (80)	13	42	588 (6.0)	229…277	4.0 3.65		217…187		4.1-4.4
					Over 100 to 300						12	38	490 (5.0)
35KhM	Q. 850–880, oil	560-650			Up to 100						13	42	588 (6.0)
					Over 100 to 300						12	38	490 (5.0)
25×1 MF (EI 10)	Q. 930–950, water and oil	620-710			Up to 200	68		667-784 (68-80)			16	50	588 (6.0)	241…277	3.9-3.65		229…197		4.0-4.3
25Kh2M1F (EI723)	N. 1030–1050 N. 950–970	680-700			Up to 200	68		667-784 (68-80)		781 (80)	12	50	490 (5.0)	241…277	3.9-3.65		229…197		4.0-4.3
20×1M1F1TR (EP182)	Quenching 970-990, oil	680-720									15		588 (6.0)
20×1M1F1BR (EP44)	Quenching 970-990, oil	680-720									14
20×13(2×13)	Quenching 1000-1050, air or oil	650-720			-	60		588-735 (60-75)			15	45		229…285	4.0-3.6		217…269		3.7-4.1
						55		539-686 (55-70)		686 (70)		50		269…217	3.7-4.4		-		-
15×11MF (1×11MF)	Quenching 1060-1100, air or oil	680-750				-		-		-	-	-	-	-	-		217…187		4.1-4.4
1×12N2VMF (EI961)	Quenching 1000-1020, oil	660-680		Up to 100		70		686-833 (70-85)		833 (85)	15	55	882 (9.0)	269…321	3.7-3.4	-			-
20×12VNMF (EP428)	Quenching 10140-1060, oil	680-720		Up to 200		68		667-784 (68-80)		784 (80)		45	588 (6.0)	241…285	3.9-3.6	229…197			4.0-4.3
18×12VMBFR (EI993)	Quenching 1030-1050, oil
18×11MNFB (EP291)	Quenching 1080-1100, oil	700-740														-			-
08×16N13M2B (EI680)	Austenitizing 1100-1130, air	Aging 750±10; 10 h		Not limited		-		-		-	-	-	-	-	-	187…143			4.4-5.0
10X11H22T3MP (EI696M)	-	780±10; 16 h + 650±10; 16 h				70		685 (70)		980 (100)	12	14	490 (5.0)	388…302	3.1-3.5	-			-
31×19N9MVBT (EI572)	Austenitizing 1140-1180, water	Aging 750-800; 15 h				32		314 (32)		588 (60)	30	40	588 (6.0)	Not less than 187	Not more than 4.4
KhN35VT (EI612)	Austenitizing 1080-1100, 1-1.5 h, water	Aging 850-900; 10 h + 700±10; 10-50 h				40		392 (40)		735 (75)	15	25
Notes: 1. The specified tempering regime may be refined in terms of temperature and duration depending on the cross-sectional dimensions of the blanks. 2. The tempering temperature of blanks for nuts must be approximately 30°C higher than the tempering temperature of blanks for bolts and studs. 3. The aging duration of KhN35VT (EI612) steel is determined by the titanium content in the steel. For a titanium content at the lower limit of 1.1-1.2% for blanks with a diameter (thickness) up to 100 mm, the aging duration is 10-50 h; for over 100 mm, not less than 50 h. For a higher titanium content, the aging duration is 10-50 h, with an aging duration of 50 h; for a higher content, 25-40 h. 4. For aging of grades 35Kh, 40Kh, 30KhMA and 35KhM with a blank diameter or side dimension of more than 80 mm, a reduction of the yield strength by 20 MPa (2 kgf/mm²) is permitted. 5. Stud-nut and bolt-nut sets may be made from different steel grades, and nuts may be made from steel 30, 35, 40 with a hardness of not more than HB 163, and from steel 45 with a hardness of not more than HB 187. In this case, the hardness of the nuts must be at least 12 Brinell units (HB) lower than the hardness of the stud or bolt. 6. The hardness of nuts may be equal to the hardness of studs or bolts if one of the connection elements undergoes strengthening chemical-thermal treatment or thread rolling. 7. Steel 20×1M1F1BR (EP44) may be heat-treated according to the normalizing + step tempering regime. 8. For fastening parts of steam and hot-water boilers, except for boilers with electric heating and boilers intended for transport installations, the elongation at break on longitudinal specimens must be greater than 10⁴/σv (MPa), but not less than 12%; the ratio of yield strength to tensile strength in a tensile test specimen at 20°C temperature must not exceed 0.85; the minimum impact toughness values on longitudinal specimens for a type 1 specimen per GOST 9454-78 must be not less than 490 kJ/m² for a blank diameter (thickness) of up to 100 mm. When these elongation and impact toughness requirements are met, the use of steels with a ratio of yield strength to tensile strength (per specimen) exceeding 0.85 is permitted.

(Amended and supplemented edition, Amendment No. 3).

1.18. The permissible curvature of bolt and stud shanks must not exceed 0.2 mm, and of straight sections of clamps — 0.4 mm per 100 mm of length for thread diameters up to 24 mm; 0.1 mm and 0.2 mm respectively per 100 mm of length for diameters over 24 mm.

For bolts and studs subjected to thermochemical treatment at finished dimensions, the permissible curvature must not exceed the limits specified in the product drawing and agreed with the customer.

The straightness tolerance of the straight sections of a clamp must not exceed the permissible deviations of the dimension between the ends of the clamp.

1.19. Tears and chipping of the thread crests of fasteners with a thread diameter up to 48 mm exceeding the limits established by GOST 1759-70, GOST 1759.2-82, GOST 1759.3-83 are not permitted; for fasteners (except studs) with a thread diameter over 48 mm, exceeding the limits established by GOST 18126-72 are not permitted.

Tears and chipping of the thread crests of studs with a thread diameter over 48 mm are not permitted if they extend in depth beyond the pitch diameter of the thread, or if their length exceeds 1% of the total thread length along the helix, or, within a single turn — 30 mm for studs with a thread diameter up to 100 mm and 40 mm for studs with a thread diameter over 100 mm.

Dents on the thread that prevent the go gauge from being screwed in are not permitted. Hairline cracks are not permitted on the threaded surface of fasteners of categories II–IV.

1.20. The machined surface of finished products must not have cracks, tears, laps, torn metal, scale, and non-removable rust.

On the non-threaded machined surface of fasteners of quality group 1, hairline cracks are not permitted upon visual inspection.

On the non-threaded machined surface of fasteners of quality groups 2–5, hairline cracks exceeding the limits specified in Table 4 are not permitted upon visual inspection.

For fasteners made of category I steel and ordinary-quality category II steel, hairline cracks are not regulated.

1.17–1.20 (Amended edition, Amendments No. 1, 2).

1.21. A step formed when drilling the central hole from both sides along the length of the shank between the threads (studs of types V, G and D) is not permitted.

1.22. Studs with a center hole may be manufactured in accordance with GOST 14034-74.

1.23. The deviation from perpendicularity of the axis of the eye bolt socket in studs of types V, G and D is per GOST 4751-73.

1.22, 1.23 (Amended edition, Amendment No. 1).

1.24. The taper of the hexagon faces of stamped cap nuts must not exceed 1°30’.

1.25. Washers must not have burrs or sharp edges.

1.26. In a threaded joint, the protruding part of the thread of the bolt, stud, or clamp must be at least one and a half turns on each side of the engaged nut. A reduction of the external protruding part of the thread of the bolt, stud, or clamp with a nominal thread diameter up to 48 mm is permitted if the nut is manufactured in accordance with GOST 9064-75 and the load-bearing thread length per GOST 1759-70 is simultaneously ensured.

1.26 (Introduced additionally, Amendment No. 3).

2. ACCEPTANCE RULES

2.1. The rules for acceptance of fasteners based on appearance and dimensions are per GOST 17769-83; for fasteners subjected to thermochemical treatment, per the working drawings.

2.2. Fasteners are submitted for acceptance in lots. A lot must consist of products of one size, manufactured from one batch of blanks with one type of coating.

2.2.1. A lot of bolts, studs, nuts and washers must have a mass, kg, not exceeding, for diameters:

up to M16 … 150

from M20 to M27 … 400

from M30 to M39 … 750

from M42 and above … 1000

The mass of a lot of fasteners intended for equipment assembly, as well as the mass of a lot of plugs and clamps, is not limited.

2.2.2. For parts of quality group 2, the lot of blanks must consist of steel of one grade, one melt, and one heat-treatment batch.

For parts of quality groups 1, 3 and 4, the lot of blanks must consist of steel of one grade, one melt, one heat-treatment batch, or of the same heat-treatment regime (quenching or normalizing plus tempering).

For parts of quality group 5, the lot of blanks must consist of steel of one grade, one heat-treatment batch, or the same heat-treatment regime.

2.1–2.2 (New edition, Amendment No. 3).

Table 4

Total area of the controlled non-threaded machined surface of the part, cm²	Number of hairline cracks		Maximum length of hairline cracks, mm, not more than	Total extent of hairline cracks, mm, not more than
	Open-melted metal	Electroslag and vacuum-arc remelted metal
				Open-melted metal	Electroslag and vacuum-arc remelted metal
Up to 50	2	1	3	5	3
Over 51 to 100	3	2	3	8	5
» 101 » 200	4	2	4	10	6
» 201 » 300	6	3	4	15	8
» 301 » 400	8	4	5	20	10
» 401 » 600	9	5	6	30	18
» 601 » 800	10	5	6	40	24
» 801 » 1000	11	6	7	50	30
» 1001 » 1200	12	6	7	55	30
» 1201 » 1400	13	6	7	60	30
» 1401 » 1600	14	7	7	65	35
» 1601 » 1800	15	7	7	70	35
» 1801 » 2000	16	7	7	75	35
» 2001 » 2200	17	8	7	80	40
» 2201 » 2400	18	8	7	86	40
» 2401 » 2600	19	8	7	90	40
» 2601 » 2800	20	9	7	95	45
» 2801 » 3000	21	9	7	100	45
» 3000 » 3200	22	9	7	105	45
» 3201 » 3400	28	10	7	110	50
» 3401 » 3600	24	10	7	115	50
» 3601 » 3800	25	10	7	120	50
» 3800 » 4000	26	10	7	125	50
Notes: 1. On parts with an area of 200 cm² or more made of open-melted metal, clusters of more than 5 hairline cracks on individual surface areas of 10 cm² are not permitted. Clusters of hairline cracks are not permitted on parts made of ESR and VAR metal. 2. Hairline cracks oriented in a direction not coinciding with the axis of the product shank are not permitted. 3. For steel grades 12×1MF, 25×1MF (EI10), 25×2M1F (EI723), 20×1M1F1TR (EP182), 20×1M1F1BR (EP44), when inspecting hairline cracks by the magnetic method, the limits are per GOST 20072-74.

2.3. For each quality group of fasteners, the list of mandatory delivery characteristics, the scope and types of inspection are specified in Table 2.

(New edition, Amendment No. 3).

Mechanical properties are inspected on finally heat-treated blanks. It is permitted to evaluate mechanical properties on specimens taken from the machining allowances on finished products of quality groups 1 and 2.

For fasteners made of category I and II steel, instead of testing mechanical properties on specimens, it is permitted to test the fasteners themselves in accordance with GOST 1759-70, in the amount of 2% of the lot, but not less than 2 pieces.

The choice of test method is made by the manufacturer of the fasteners.

(Amended edition, Amendment No. 1).

2.4. The sampling method for rolled blanks is per GOST 7564-73, for forgings — per GOST 8479-70.

When determining mechanical properties, one tensile specimen and three impact-toughness specimens are taken from each inspected blank, or from the machining allowance of the inspected product, or from a separate sample from a product subjected to thermochemical treatment.

For fasteners used at a working pressure of up to 4 MPa, provided that hardness is inspected in an amount of 2% of the lot, it is permitted to take from a lot with a mass of not more than 1000 kg:

for category I steel — one tensile specimen;

for category II steel — one tensile specimen and two impact-toughness specimens.

For fasteners used at a working pressure of up to 4 MPa, for steel categories I and II, in mass and batch production with a well-established manufacturing process, the inspection scope is permitted to be determined using mathematical statistics methods per GOST 20736-75.

2.4 (Revised, Amendment No. 3).

2.5. For products longer than 600 mm, the hardness of heat-treated (quenching or normalizing plus tempering) blanks made of steel categories III and IV is determined at both ends; the difference in hardness values on one blank must not exceed 20 Brinell units (HB).

2.6. If the test results of at least one specimen are unsatisfactory, the tests are repeated on double the number of specimens taken from the same blanks or parts, or from other blanks and parts with the same hardness. Repeat tests are performed for the parameters for which unsatisfactory results were obtained. If, during repeat testing, at least one specimen shows values below those specified in Table 3, the test results are considered unsatisfactory. Mechanical properties are determined on blanks or parts with the subsequent hardness level.

2.7. A batch of fasteners may be resubmitted for acceptance after re-sorting by hardness values. Repeat heat treatment of finished products is not allowed.

A batch of blanks whose mechanical properties were checked directly on the blanks may be approved for manufacturing fasteners after re-sorting by hardness values or after repeat heat treatment, followed by control testing in the scope of Table 2.

If the results of repeat testing are unsatisfactory, the batch of blanks is rejected.

The number of repeat heat treatments of blanks must not exceed two; additional tempering of blanks and heating for chemical-thermal treatment are not considered repeat heat treatment.

(Amended edition, Amendment No. 1).

2.8. Inspection of the decarburized layer is performed on one section sample per batch for fasteners manufactured by thread rolling on calibrated blanks made of pearlitic-class steel.

When threading is performed by cutting (removing metal from the surface of the blanks), inspection of the decarburized layer is not performed.

(Revised edition, Amendment No. 2).

2.9. By agreement between the manufacturer and the consumer, sample evaluation of the yield strength, long-term strength, or conditional creep limit of 10⁻⁵%/h of the metal of bolts and studs at the design temperature is performed.

2.9 (Revised, Amendment No. 3).

2.10. Finished fasteners undergo 100% visual inspection, checking of thread dimensions, checking of overall product dimensions, surface roughness, and checking of marking.

2.11. Standards for permissible defects under ultrasonic testing — per GOST 23304-78.

(Added, Amendment No. 2).

3. TEST METHODS

3.1. The chemical composition of steel is determined per GOST 22536.0-77 – GOST 22536.13-77, GOST 20560-81, GOST 12344-78, GOST 12345-80, GOST 12346-78, GOST 12347-77, GOST 12348-78, GOST 12349-83, GOST 12350-78, GOST 12351-81, GOST 12352-81, GOST 12353-78, GOST 12354-81, GOST 12355-78, GOST 12356-81, GOST 12357-84, GOST 12358-82, GOST 12359-81, GOST 12360-82, GOST 12361-82, GOST 12362-79, GOST 12363-79, GOST 12364-84, or by other methods providing the required accuracy.

(Revised edition, Amendment No. 2).

3.2. Hardness determination (clause 1.8) — per GOST 9012-59; of the surface-hardened layer — per GOST 9013-59.

(Amended edition, Amendment No. 3).

3.3. Tensile testing of specimens (clause 1.8) — per GOST 1497-84.

3.4. Impact toughness testing (clause 1.8) — per GOST 9454-78 (type I specimen).

3.5. Testing of fasteners with a nominal thread diameter up to 48 mm made of steel category II for proof and test load (clause 1.7) — per GOST 1759-70.

3.6. Long-term strength testing (clause 1.12) — per GOST 10145-81; creep testing — per GOST 3248-81.

(Amended edition, Amendment No. 3).

3.7. Determination of the depth of the decarburized layer (clause 1.11) is performed based on microstructure in accordance with GOST 1763-68. Inspection by other methods providing accuracy no lower than the microstructure evaluation method is permitted.

3.8. Inspection of washers — per GOST 18123-82.

3.9. Visual inspection of finished products for the absence of defects is performed visually without the use of magnifying devices. The use of other non-destructive testing methods adopted at the manufacturing plant is permitted, provided that the results are not used for acceptance purposes.

3.10. Checking the deviation from perpendicularity of the side surface (1.17) of nuts relative to the bearing surface is performed using gauges or protractors.

3.11. Other test methods — per GOST 1759-70, GOST 18126-72, and GOST 18123-82.

3.12. Ultrasonic testing — per GOST 24507-80.

(Added, Amendment No. 2).

4. MARKING, PACKAGING, TRANSPORTATION AND STORAGE

4.1. General requirements for temporary corrosion protection, packaging, transportation, storage, and container marking — per GOST 18160-72 and GOST 9.014-78.

(Revised edition, Amendment No. 2).

4.2. Bolts, studs, and nuts, plugs, and clamps made of steel categories I and II are marked per GOST 1759-70.

4.3. On the end face of the nut end of bolts, studs of all types, type B nuts, and on the side surface of type A nuts and washers, the following are marked: the manufacturer’s trademark, the material grade, the symbol for the melting method for electroslag remelting — Sh, and vacuum-arc remelting — VD, and the batch (melt) number.

At the consumer’s request, the steel category and the product quality group are marked.

For fasteners intended for equipment manufactured at the same plant, marking only the batch number is permitted.

Plugs are marked on the end face of the head; clamps are marked on a straight section at a distance of at least 20 mm from the thread.

4.2, 4.3 (Amended, Amendments No. 1, 2).

4.4. The final acceptance mark shall be stamped.

4.5. For bolts, studs and nuts, plugs and clamps with a diameter up to M27, and washers with a thickness up to 10 mm, marking is permitted to be applied on a tag.

(Revised edition, Amendments No. 1, 2).

4.6. Products with a left-hand thread are marked per GOST 2904-45.

4.7. The font and size of marking characters are determined by the manufacturer. Marking characters must be clear and clearly visible to the naked eye.

4.8. If the marking indicates the steel grade designation instead of the alphanumeric notation per Table 1, for example 25Kh1MF, 25Kh2M1F, 20Kh1M1F1TR, etc., conventional marking EI10, EI723, EP182, etc., respectively, is permitted.

4.9. (Deleted, Amendment No. 2).

4.10. Fasteners must be stored in an enclosed space.

4.11. Each batch of fasteners is accompanied by a document certifying their compliance with the requirements of this standard.

For fasteners made of steel category I and II and intended for pressure up to 4 MPa, the document contains:

the name of the manufacturing plant,

the type and size of the parts,

the number of parts and the mass of the batch,

the steel grade,

the property class or test results,

the designation of this standard,

stamp of the quality control department.

For fasteners made of steel category I and II and intended for pressure above 4 MPa, as well as for parts made of steel category III and IV, the document additionally specifies:

the steel melting method for electroslag and vacuum-arc remelting,

the chemical composition,

the steel category and quality group of the finished products,

the results of the tests performed,

instructions on the use of protective coatings and the coating characteristics.

4.11 (Revised, Amendment No. 3).

APPENDIX 1

For reference

Long-term strength limits

Steel grade	Long-term strength limits, kgf/mm², at temperature, °C
	425	450	500	525	550	565	580	600	650	700
30KhMA, 35KhM	34 29	30 23
25Kh1MF (EI10)	55 45	46 37	26 17
25Kh2M1F (EI723)			33 25	27 20	16-22 (14) 540°
20×1M1F1TR (EP182)	50 46	48 45	39 33	35 30	33 28	29 25	27 20
20×1M1F1BR (EP44)		49 40	35 30	31 26.5	27.5 23.5	26 22	24 20
20×13	32 27	29.5 26
15×11MF					16-21 13-16	(14-16.5)
20×12VNMF (EP428)		50 48	39 35		22	24 19
18×12VMBFR (EI993)		48 42	36 31			560° 25 22
13Kh11N2V2MF (EI961)			35* 32.5				15* 10.5
08×16N13M2B (EI680)					26 21		20 15		13 9.5
31×19N9MVBT (EI572)						560° 30 26	23.5-27 20-24		18-21 15-17
08Kh18N10T (OKh18N10T)			25 20	21 17		15.5 13	13.5 10		8 6	5.5
KhN35VT (EI612)			45 36	40 33		39 32	26-31 21-26		20 16
10Kh11N22T3MR			50* 47.5				32.5* 31.0			15
*Data for 25,000 h. Notes: 1. The numerator shows the long-term strength limits for 10⁴ h, the denominator for 10⁵ h. 2. Values in parentheses are extrapolated.

Appendix 1 (Revised, Amendment No. 3).

APPENDIX 1a

For reference

Conditional creep limit

Steel grade	Conditional creep limit, kgf/mm², at temperature, °C
	425	450	475	500	525	550	565	580	600
30XM	14	11
35KhM		13
25Kh1M1F (EI10)		23	14.5	8
25Kh2M1F (EI723)						7
20×1M1F1TR (EP182)							12	9.5
20×1M1F1BR (EP44)		24		16			11
20×13		12.8	7.6	4.8		3
15×11MF						9
20×12VNMF (EP428)		28		17		10-12
18×12VMBFR (EI993)							560° 15
08×16N13M2B (EI680)						16-18		9-12	5-7
31Kh19N9MVBT(EI572)							560° 17	11-13	8-10
08Kh18N10T (OKh18N10T)								7.5
KhN35VT (EI612)								18	13-14

Appendix 1a (Added, Amendment No. 3).

APPENDIX 2

For reference

Steel grade	Modulus of elasticity E·10⁻⁴, kgf/mm², at temperature, °C
	20	100	200	300	400	450	500	550	600	650
10, 20, 25, 30, 35, 40	2.13	2.10	1.98	1.90	1.85	-	1.79	-	-	-
35Kh, 40Kh, 15KhM, 30KhMA, 35KhM	2.18	2.15	2.08	2.01	1.92	-	1.79	-	-	-
12Kh1MF (12KhMF), 25Kh1MF (EI10), 25Kh2M1F (EI723), 20Kh1M1F1TR (EP182), 20Kh1M1F1BR (EP44)	2.15	2.12	2.08	2.02	1.94	-	1.83	1.77	1.70	-
20Kh13 (2Kh13), 15Kh11MF (1Kh11MF), 20Kh12VNMF (EP428), 18Kh11MNFB (EP291), 1Kh12N2VMF (EI961), 18Kh12VMBFR (EI903)	2.28	2.22	2.13	2.05	1.93	-	1.84	1.75*	1.70	-
12Kh18N10T (Kh18N10T), 08Kh18N10T (0Kh18N10T), 08Kh16N13M2B (EI680), 31Kh19N9MVBT (EI572), KhN35VT (EI612)	2.05	2.02	1.97	1.90	1.81	1.80	1.73	1.70	1.65	1.60
10Kh11N22T3MR (EI696M)	1.9	1.81	1.69	1.58	1.48	1.42	1.37	1.33	1.31	1.30
* At 565 °C, the modulus of elasticity equals 1.73.

APPENDIX 3

For reference

Steel grade	Coefficient of linear expansion α·10⁶ in the temperature range, °C
	20-100	20-200	20-300	20-400	20-500	20-550	20-600	20-700
10, 20, 25, 30, 35, 40, 45	11.35	12.36	12.93	13.44	14.1	-	-	-
35Kh, 40Kh, 15KhM, 30KhMA, 35KhM	11.6	12.3	12.8	13.55	14.0	-	-	-
12Kh1MF (12KhMF), 25Kh1MF (EI10), 25Kh2M1F (EI723), 20Kh1M1F1TR (EP182), 20Kh1M1F1BR (EP44)	11.65	12.4	12.8	13.3	13.5	13.7	14.3	-
20Kh13 (2Kh13), 15Kh11MF (1Kh11MF), 20Kh12VNMF (EP428), 18Kh11MNFB (EP291), 1Kh12N2VMF (EI961), 18Kh12VMBFR (EI903)	10.5	10.8	11.1	11.5	11.8	-	12.05	-
12Kh18N10T (Kh18N10T), 08Kh18N10T (0Kh18N10T), 08Kh16N13M2B (EI680), 31Kh19N9MVBT (EI572), KhN35VT (EI612), 10Kh11N22T3MR (EI696M)	15.3	15.9	16.5	16.9	17.3	-	17.7	18.2

APPENDIX 4

For reference

Steel grade	Hardness, HB or σ0.2	Test temperature, °C	s₀, kgf/mm²	Residual stress, kgf/mm¹, over time, h
				100	500	1000	2000	3000	4000	5000	8000	10000	12000
20	-	200	10	9.4	9.2	9.2	9.0	9.0	-	(8.6)	-	(8.2)	-
			15	11.1	10.5	10.9	10.7	10.5	-	(10.2)	-	(9.7)	-
			18	11.7	11.2	11.2	11.0	10.8	-	(10.5)	-	(10.0)	-
		300	10	8.8	8.7	8.7	8.6	8.5	-	(8.3)	-	(8.0)	-
			15	10.6	10.3	10.3	10.1	10.1	-	(9.8)	-	(9.6)	-
		400	10	7.8	7.3	7.3	7.0	7.0	-	(6.8)	-	(6.5)	-
			12	8.5	8.1	8.0	7.7	7.6	-	(7.0)	-	-	-
		450	7	4.8	4.5	4.1	-	-	-	(3.7)	-	(2.9)	-
			19	6.6	6.2	6.0	-	-	-	-	-	-	-
40Kh	HB 269	300	27	25.5	25.0	24.5	-	-	-	23.0	-	-	-
	HB 207		26	23.5	22.5	22.0	-	-	-	20.0	-	-	-
	HB 207	350	19	15.5	14.0	13.5	-	-	-	11.5	-	-	-
			27	21.0	19.0	18.0	-	-	-	15.0	-	-	-
			42	29.5	27.0	26.0	-	-	-	21.5	-	-	-
40Kh	HB 207	400	23	12.0	10.0	8.5	-	-	7.0	-	-	-	-
			29	13.5	10.5	9.8	-	-	7.8	-	-	-	-
			36	14.0	11.0	10.0	-	-	8.6	-	-	-	-
	HB 262		20	17.8	17.1	16.9	-	15.9	-	14.7	-	13.5	-
			25	22.4	21.5	21.2	-	20.0	-	19.5	-	18.2	-
30KhMA 35KhM	HB 269	400	15	8.9	6.8	6.5	-	-	-	(5.3)	-	(4.5)	-
			25	13.8	10.6	9.9	-	-	-	(7.7)	-	(6.4)	-
			35	19.0	13.6	12.0	-	-	-	(9.8)	-	(8.2)	-
30KhMA 35KhM	HB 269	450	15	8.3	6.6	6.1	-	-	-	(4.7)	-	(3.3)	-
			25	12.3	9.3	8.7	-	-	-	(6.8)	-	(5.2)	-
25Kh1MF (EI10)	HB 293	500	15	9.5	8.3	7.8	7.2	6.9	-	(5.7)	-	(3.8)	-
			25	14.8	12.8	12.0	11.0	10.4	-	(9.3)	-	(7.2)	-
			35	19.7	17.1	16.0	15.1	14.0	-	(12.5)	-	(9.4)	-
		525	20	-	8.0	-	5.0	-	-	-	-	-	-
20×1M1F1TR (EP182)	σ0.2=75 kgf/mm²	450	25	21.5	-	20.7	-	20.3	-	20.1	19.7	19.4	19.4
			30	25.8	-	25.0	-	24.3	-	23.8	23.6	23.2	23.2
			35	29.8	-	28.8	-	28.1	-	27.5	27.2	27.0	26.9
		500	25	20.2	-	19.3	-	18.6	-	18.2	17.6	17.4	-
			30	24.3	-	22.8	-	22.5	-	21.9	21.3	20.7	20.3
			35	28.2	-	26.2	-	25.2	-	24.9	24.3	24.2	22.6
		565	20	14.4	-	13.2	-	11.6	-	11.2	10.5	10.3	-
			25	17.5	-	15.0	-	13.5	-	12.4	11.6	11.1	9.7
			30	19.8	-	17.5	-	15.5	-	14.3	13.3	13.1	-
			35	22.4	-	19.1	-	16.8	-	-	-	(14.5)	-
		580	25	16.2	-	14.0	-	12.3	-	11.6	10.2	8.7	-
			30	17.7	-	15.1	-	13.8	-	12.9	11.2	10.5	10.5
			35	20.6	-	17.5	-	15.0	-	13.3	-	(11.5)	-
25Kh2M1F (EI723)	σ0.2=78 kgf/mm²	500	30	-	-	-	-	17.5	-	-	-	16.5	-
			35	-	-	-	-	20.0	-	-	-	17.0	-
		525	25	-	15.0	14.5	13.6	13.0	-	-	11.5	10.8	-
			30	-	19.7	17.0	16.0	15.5	-	-	13.5	10-13	-
			35	-	20.2	19.0	17.0	16.5	-	-	14.5	12-13.5	-
		550	25	-	13.0	11.0	10.5	10.0	-	-	7.3	4.3-6.7	-
			30	-	16.0	14.5	12.5	11.0	-	-	8.0	7.0	-
			35	-	17.7	16.0	14.0	12.5	-	-	8.5	7.5	-
20×1M1F1BR (EP44)	σs0.2=68-80 kgf/mm²	450	25	21.5	21.2	21.0	20.8	20.6	20.3	20.0	19.6	19.5	19.3
			30	25.5	25.0	24.8	24.5	24.2	24.0	23.7	23.4	23.2	23.0
			25	30.0	29.5	28.8	28.5	28.0	27.8	27.5	27.2	27.0	26.7
		500	25	21.0	19.5	19.2	18.7	18.5	18.2	18.0	17.5	(17.0)	-
			30	24.0	22.5	22.0	21.8	21.6	21.0	20.6	20.3	(20.0)	-
			35	29.0	27.5	26.5	26.0	25.5	24.8	24.2	23.5	(23.0)	-
		565	25	16.5	15.5	14.3	13.2	12.5	12.0	11.5	10.8	10.3	10.0
			30	20.0	18.0	17.3	15.5	15.0	14.3	14.0	13.2	13.0	12.8
			35	22.6	20.0	19.0	17.6	17.0	16.5	16.0	15.0	14.5	14.0
		580	25	15.7	13.5	12.7	11.7	11.0	10.6	10.4	10.0	9.8	9.5
			30	15.0	16.3	15.3	14.0	13.2	12.5	12.0	11.0	10.8	10.5
			35	22.0	19.5	17.5	16.0	15.0	14.0	13.5	12.0	11.5	-
20×12VNMF (EP428)	HB 269	400	25	21.7	-	20.8	-	20.5	-	20.5	-	(20.5)	-
			30	25.7	-	24.6	-	24.3	-	23.9	-	(23.5)	-
			35	29.8	-	28.6	-	28.0	-	27.9	-	(27.5)	-
			40	34.0	-	32.5	-	32.2	-	32.0	-	(31.5)	-
		450	25	19.6	-	18.5	-	18.1	-	17.9	-	17.5	16.4**
			30	23.3	-	22.1	-	21.5	-	21.0	-	20.5	19.4**
			35	27.0	-	25.4	-	24.7	-	24.4	-	24.0	22.5**
			40	30.6	-	28.4	-	27.4	-	26.8	-	26.5	-
		500	25	16.8	-	-	-	13.5	-	13.0	-	11.3	10.3**
			30	20.0	-	-	-	17.0	-	16.0	-	14.0	12.2**
			35	23.0	-	-	-	18.8	-	18.0	-	16.0	14.4**
		565	35	16.0	-	12.5	-	11.0	-	9.5	-	7.0	-
			30*	23.0	-	18.0	-	15.0	-	14.0	-	12.5	-
			35*	25.0	-	19.5	-	17.0	-	16.0	-	14.0	19.4***
18Kh12VMBFR (EI 993)	σ0.2=68-80 kgf/mm²	450	25	21.0	-	20.5	-	-	20.0	-	-	-	19.4***
			30	25.0	-	24.5	-	-	23.9	-	-	-	23.0***
			35	28.5	-	28.0	-	-	27.2	-	-	-	26.3***
		500	25	19.7	-	18.4	-	-	17.2	-	-	-	-
			30	23.0	-	21.5	-	-	20.3	-	-	-	-
			35	26.9	-	24.9	-	-	23.2	-	-	-	-
		565	25	15.0	14.3	13.4	12.6	12.3	11.6	11.2	10.2	9.8	-
			30	17.5	16.8	15.8	14.8	14.6	13.9	13.7	12.1	11.5	-
			35	20.4	19.0	18.3	17.0	16.4	16.0	15.5	13.5	13.0	-
		580	30	22.0	15.0	13.9	12.0	11.5	11.0	10.8	9.8	9.0	-
			35	20.5	17.5	16.0	14.0	13.2	13.0	12.5	11.0	10.5	-
08×16N13M2B (EI680)	HB 143…187	600	15	9.5	8.8	8.5	-	7.7	-	6.8	-	-	-
			20	12.1	11.3	10.7	-	9.8	-	9.4	-	-	-
31Kh19N9MVBT (EI&7.2.)	HB over 207	560	20	15.5	14.7	14.4	-	13.9	-	-	-	-	-
			20****	18.3	17.7	17.3	-	16.9	-	-	-	-	-
		600	20	13.8	12.5	11.7	-	-	9.9	-	-	-	-
			25	16.0	13.5	12.3	-	-	9.6	-	-	-	-
			30	18.0	16.3	13.9	-	-	10.0	-	-	-	-
		650	20	11.0	9.0	8.2	-	-	6.5	-	-	-	-
			25	13.0	10.3	9.1	-	-	7.5	-	-	-	-
KhN35VT (EI612)	HB over 207	500	45	35.0	34.4	34.3	-	33.8	-	32.6	-	32.4	-
		600	15	13.9	13.8	13.7	-	13.6	-	13.5	13.5	13.0	-
			20	18.2	18.0	17.9	-	17.6	-	17.3	17.1	17.0	-
			25	22.3	21.9	21.7	-	21.3	-	20.9	20.4	20.0	-
			30	25.3	24.9	24.6	-	23.9	-	23.4	22.7	22.5	-
		650	15	13.2	13.0	12.8	-	12.1	-	11.8	11.5	11.2	-
			20	17.5	16.8	16.4	-	15.6	-	14.9	14.3	14.0	-
			25	21.0	20.5	19.9	-	18.4	-	18.0	16.6	16.0	-
			45	25.0	24.2	23.2	-	20.3	-	19.0	17.4	16.5	-
10X11H22T3MP (EI696M)	HB 285…302	450	25	23.7	23.7	23.7	23.5	23.5	-	23.2	23.0	22.8	-
			35	32.8	32.8	32.7	32.7	32.6	-	31.5	30.5	30.0	-
			45	42.6	42.6	42.2	42.2	42.2	-	41.5	40.8	40.0	-
		500	25	23.3	23.1	23.0	22.9	22.9	-	22.8	22.7	22.6	22.4
			35	32.5	32.4	32.1	31.9	31.8	-	31.5	31.4	31.3	31.2
			45	41.8	41.7	41.2	41.1	41.0	-	40.7	40.3	40.1	40.0
		650	15	13.1	11.4	10.9	10.0	9.5	-	9.0	7.1	-	-
			25	21.4	17.8	14.5	12.6	11.7	-	10.3	8.5	7.8	7.1
			35	28.3	23.4	18.6	16.2	14.8	-	12.6	9.1	8.8	8.2
			45	34.9	28.5	23.1	19.7	17.8	-	15.7	12.5	11.5	10.9
Values in parentheses are extrapolated: * - after repeated immersions over 50-10000 h, ** - over 20000 h, *** over 13000 h, **** - repeated immersion after 25 h.

APPENDIX 5

Recommended

Steel grade	Hardness of annealed or high-temperature tempered steel		Recommended annealing (high-temperature tempering) temperatures, °C
	Indentation diameter, mm, not less than	Hardness number HB, not more than
35Kh	4.3	197	830-850
40Kh	4.1	217
15KhM	4.5	179	850-870
30KhMA	4.0	229
35KhM	3.9	241
12Kh1MF	4.1	217	900-950
25KhIMF (EI10), 25Kh2M1F (EI723), 20Kh1M1F1TR (EP182), 20Kh1M1F1BR (EP44)	4.0	229
20Kh13 (2Kh13), 15Kh11MF (1Kh11MF)			700-750
20Kh12VNMF (EP428), 18Kh11MNFB (EP281), 18Kh12VMBFR (EI993), 1Kh12N2VMF (EI961)			700-720
12Kh18N10GG (Kh18N10T), 08Kh18N10T (0Kh18N10T), 08Kh16N13M2B (EI680), 31Kh19N9MVBT (EI572), 10Kh11N22T3MR (EI696M), KhN35VT (EI612)	Steel is supplied in hot-rolled (forged) condition; hardness is not limited		-
Note. Cooling during annealing (high-temperature tempering) is done with the furnace down to 300°C, then in air.