GOST 18126-94 Bolts and Nuts with Thread Diameter Over 48 mm. General Specifications

GENERAL SPECIFICATIONS

INTERSTATE COUNCIL

FOR STANDARDIZATION, METROLOGY AND CERTIFICATION

MINSK

FOREWORD

1 DEVELOPED by the All-Russian Scientific Research Institute for Standardization and Certification in Mechanical Engineering of Gosstandart of Russia

2 SUBMITTED BY Gosstandart of Russia

3 ADOPTED by the Interstate Council for Standardization, Metrology and Certification (Minutes No. 6 of October 21, 1994)

The following voted in favor of adoption:

Name of state	Name of national standardization body
Republic of Azerbaijan	Azgosstandart
Republic of Armenia	Armgosstandart
Republic of Belarus	Gosstandart of the Republic of Belarus
Republic of Georgia	Gruzstandart
Republic of Kazakhstan	Gosstandart of the Republic of Kazakhstan
Kyrgyz Republic	Kyrgyzstandart
Republic of Moldova	Moldovastandart
Russian Federation	Gosstandart of Russia
Republic of Uzbekistan	Uzgosstandart
Ukraine	Gosstandart of Ukraine

3 By Decree of the Committee of the Russian Federation for Standardization, Metrology and Certification No. 526 of October 10, 1995, the interstate standard GOST 18126-94 was put into effect directly as the national standard of the Russian Federation as of January 1, 1996.

4 SUPERSEDES GOST 18126-72

5. REISSUE. October 2005

CONTENTS

1 Scope

2 Normative references

3 Basic parameters and dimensions

4 Technical requirements

5 Acceptance

6 Test methods

7 Transportation and storage

APPENDIX A (recommended) DESIGNATION SCHEME FOR BOLTS AND NUTS

GOST 18126-94

INTERSTATE STANDARD

BOLTS AND NUTS WITH THREAD

DIAMETER OVER 48 MM

General Specifications

Bolts and nuts with thread diameter over 48 mm. General specifications

Date of introduction 1996-01-01

1 SCOPE

This standard applies to bolts and nuts with thread diameter over 48 mm, product grade A and B.

2 NORMATIVE REFERENCES

This standard uses references to the following standards:

GOST 9.301-86 Unified system of corrosion and ageing protection. Metallic and non-metallic inorganic coatings. General requirements

GOST 9.302-88 Unified system of corrosion and ageing protection. Metallic and non-metallic inorganic coatings. Control methods

GOST 9.303-84 Unified system of corrosion and ageing protection. Metallic and non-metallic inorganic coatings. General requirements for selection

GOST 9.306-85 Unified system of corrosion and ageing protection. Metallic and non-metallic inorganic coatings. Designations

GOST 380-94 Common quality carbon steel. Grades

GOST 977-88 Steel castings. General specifications

GOST 1050-88 Shaped, calibrated bar stock with special surface finish from quality carbon structural steel. General specifications

GOST 2904-91 Basic interchangeability standards. Marking of parts with left-hand thread

GOST 4543-71 Rolled products from alloyed structural steel. Specifications

GOST 5632-72 High-alloy steels and corrosion-resistant, heat-resistant and high-temperature alloys. Grades

GOST 8479-70 Forgings from carbon and alloy structural steel. General specifications

GOST 9012-59 Metals. Method of Brinell hardness measurement

GOST 9013-59 Metals. Method of Rockwell hardness measurement

GOST 12414-94 Ends of Bolts, Screws and Studs. Dimensions

GOST 16093-2004 Basic interchangeability standards. Metric thread. Tolerances. Clearance fits

GOST 17769-83 Fasteners. Acceptance rules

GOST 18160-72 Fasteners. Packaging. Marking. Transportation and storage

GOST 20072-74 Heat-resistant steel. Specifications

GOST 24643-81 Basic interchangeability standards. Tolerances of form and location of surfaces. Numerical values

GOST 24705-2004 Basic interchangeability standards. Metric thread. Basic dimensions

GOST 27148-86 Fasteners. Thread run-out. Run-outs, incomplete threads and undercuts. Dimensions

3 BASIC PARAMETERS AND DIMENSIONS

3.1 In design and dimensions, bolts and nuts shall comply with the requirements established in the product standards.

3.2 Tolerances of form and location of surfaces of bolts and nuts per GOST 24643:

• symmetry tolerance of the hexagon (width across flats) relative to the axis of the bolt shank or relative to the thread axis of the nut (for product grade A items), perpendicularity tolerance of the bolt head bearing surface relative to the shank axis, coaxiality tolerance of the thread relative to the bolt shank axis, intersection tolerance of the axes of the cotter pin hole and the bolt thread, symmetry tolerance of the slots of the castle nut relative to the thread axis - to accuracy grade 14;

• symmetry tolerance of the hexagon (width across flats) relative to the axis of the bolt shank or relative to the thread axis of the nut (for product grade B items), perpendicularity tolerance of the nut bearing surface relative to the thread axis - to accuracy grade 15.

3.3 Thread of bolts and nuts per GOST 24705; thread tolerance classes: bolts - 6g, nuts - 6H per GOST 16093.

3.4 Bolt ends - per GOST 12414.

3.5 Run-outs, incomplete threads - per GOST 27148.

3.6 The designation scheme for bolts and nuts is given in Appendix A

3.7 The following are permitted for bolts and nuts:

• chamfers on the bolt bearing surface at an angle of no more than 15°;

• absence of the end chamfer on the shanks of thread-rolled products;

• rounding of the hexagon edges that does not take the circumscribed circle diameter beyond the limit deviation;

• slope of the faces (angle β in figure 1) not exceeding:

30’ - for product grade A items

1° - for product grade B items.

Note - The face slope shall not take the width across flats beyond the limit deviations.

Figure 1

• an oblique cut of the shank with width (C in figure 2) of no more than one thread pitch.

Figure 2

4 TECHNICAL REQUIREMENTS

4.1 Appearance

4.1.1 The surface of bolts and nuts shall be clean, free of corrosion traces and mechanical damage.

4.1.2 The following are not permitted for bolts and nuts:

• cracks;

• scratches that take the product dimensions beyond the limit deviations;

• seams at die split lines that increase the actual shank diameter by more than the tolerance +IT12, for product grade B;

• cutting tool marks that take the shank or head diameter beyond the limit deviations;

• burrs and sharp edges in cotter pin holes;

• burrs and dents on the thread that prevent the go gauge from being screwed on;

• tears, chipping of the thread crests on shank-type products, if their depth exceeds the limits of the pitch diameter of the thread or their length exceeds:

2% of the total thread length along the helix, and 1/6 of its length in a single turn - for product grade A;

5% of the total thread length along the helix, and 1/4 of its length in a single turn - for product grade B;

• tears and chipping of the thread crests on nuts, if their depth exceeds the limits of the pitch diameter of the thread or their length exceeds half a turn;

• reduction of the thread profile height on shank-type products leading to a reduction of the thread major diameter on more than two end turns;

• distortion of the thread profile in the area of cotter pin holes;

• rounding of the crests of the rolled thread profile that takes the thread major diameter beyond the limit deviation.

4.1.3 The following are permitted for bolts and nuts:

• surface defects provided for by the technical requirements for the bars from which the products are manufactured;

• traces of die splitting - for product grade A;

• clamp marks, feed mechanism marks, lap marks, non-removable scale and rust easily washed off with kerosene on products manufactured without coating - for product grade B;

• center hole on the end face of the head and shank;

• decrease in thread profile height with increase in minor thread diameter at the last thread turn of the nut thread;

• traces from seam cleaning;

• decrease in thread profile near the cotter pin hole.

4.2 Mechanical properties and materials

4.2.1 Mechanical properties and material grades shall conform to those specified in Table 1.

Table 1

Material name	Material designation	Material grade	Standard number	Tensile strength σb, N/mm²	Brinell hardness HB	Material grade designation (group)
				min
Carbon steels	0	St3sp	GOST 380	363	90	02
		St3kp		373
		20	GOST 1050	412	110	04
		25L-II	GOST 977	441	124
		35	GOST 1050	530	140	05
		45		598	170	06
		35		784	225 in hardened condition	07
Alloy steels	1	35Kh	GOST 4543	931	197	11
		40KhN		981	217
Corrosion-resistant steels	2	12×18N9T 12×18N10T	GOST 5632	510	-	21
		14Kh17N2		686	-	23
Heat-resistant and high-temperature steels		25Kh1MF	GOST 20072	882	-	25
Notes 1 For the manufacture of products from material groups 02, 04, 05 and 06, the use of free-cutting steel is permitted. 2 For the manufacture of nuts from materials 02, 04, 05 and 06, the use of phosphorous steel is permitted. 3 The use of Bessemer steels for the manufacture of bolts and nuts is not permitted.

4.2.2 With the consent of the customer, bolts may be manufactured from rimmed steel grades.

4.2.3 Material grades not specified in Table 1 that provide mechanical properties not lower than those specified, as well as non-ferrous alloys, may be used for the manufacture of bolts and nuts.

4.3 Coatings

4.3.1 Bolts and nuts shall be manufactured with one of the coating types specified in Table 2, or without coating.

Table 2

Coating type	Coating designation
	per GOST 9.306	numeric
Zinc, chromated	Ts.Kh	01
Oxide, oil-impregnated	Khim.Oks.prm	05
Phosphate, oil-impregnated	Khim.Fos.prm	06

Other coating types may be used, in accordance with GOST 9.303.

4.3.2 Coating thickness selection - in accordance with GOST 9.303.

4.3.3 Technical requirements for coatings - in accordance with GOST 9.301.

4.4 Marking

4.4.1 Bolts and nuts shall bear the manufacturer’s trademark and the group designation in accordance with Table 1.

The letter A shall be marked on products of product grade A.

4.4.2 Marking symbols may be raised or recessed.

When marking with raised symbols, an increase of 0.3 mm in the maximum permissible head height of the bolt or nut is permitted.

4.4.3 The dimensions of the marking symbols are determined by the manufacturer.

4.4.4 Marking symbols shall be applied:

for bolts - on the end face or side surface of the head;

for nuts - on one of the end faces.

Symbols on the side surface of the head shall be recessed.

4.4.5 Marking symbols shall be clearly visible to the naked eye regardless of the surface finish quality of the product.

4.4.6 Instead of marking each product (except for the letter A), marking may be applied to the packaging in which the products are packed.

4.4.7 Marks on products with left-hand thread - in accordance with GOST 2904.

5 ACCEPTANCE

5.1 Acceptance rules - in accordance with GOST 17769.

6 TEST METHODS

6.1 The appearance of products shall be checked visually without the use of magnifying devices. In disputed cases, a magnifying glass with 3x magnification may be used.

Notes

1 Surface roughness is checked by comparison with reference samples.

2 Checking for cracks by special methods and surface roughness by instruments is permitted.

6.2 Product dimensions are checked using limit gauges, templates, universal measuring instruments, control dies, etc.

6.3 Thread is checked using limit gauges. For bolts with cotter pin holes, screwing on the “no-go” thread gauge until it fully passes the hole is permitted.

6.4 Coating thickness is checked on the head of bolts, on the flats or end faces of nuts. The choice of coating thickness measurement method is at the manufacturer’s discretion. Coating quality control - in accordance with GOST 9.302.

6.5 Perpendicularity of the bearing surface of the bolt head to the shank axis is measured with an angular template or a feeler gauge, by the gap between the bearing surface of the head and the end face of the control die. The hole diameter in the die shall correspond to that specified in Table 3.

Table 3

Nominal thread diameter	Diameter of die holes by product grade
	B	A
52	56	54
56	62	58
64	70	66
72	78	74
76	82	78
80	86	82
90	96	93
100	107	104
110	117	114
125	132	129
140	147	144
160	168	165
Note - Limit deviations of hole diameters - as per H13.

Perpendicularity of the nut’s bearing surface to the thread axis is checked with a feeler gauge by the gap between the end faces of the nut and the control ring, screwed onto a threaded mandrel until they come into contact with each other.

Checking perpendicularity of the bearing surface of products by monitoring end-face runout is permitted.

6.6 Straightness of the bolt shank is checked by free entry of the shank into a control die. The hole diameter in the die shall correspond to that specified in Table 3. The depth of the hole in the die shall be not less than the length of the product being checked.

6.7 The taper of the head flats is checked with an angular template.

6.8 If the shank is cut at an angle, the bolt length is checked along its longer side.

6.9 The position of the slots of castle nuts and slotted nuts is checked with a gauge whose thread is made to the dimensions of the “go” thread gauge of the nut being checked, and whose pin diameter equals the cotter pin diameter (Figure 3).

Figure 3

The shape of the slot base is not checked.

Other inspection methods are permitted.

6.10 The diameter of the circumscribed circle of hexagon nuts and hexagon head bolts is checked in the middle part of the height of the nut or bolt head, over a section equal to half their height.

6.11 Thread roughness is checked on the side surfaces of the profile.

6.12 The roughness of the shank end face is not checked.

6.13 Dimensions not limited by tolerances are not checked. Their achievement shall be ensured by the manufacturing process.

6.14 Hardness is determined in accordance with GOST 9012 or GOST 9013. Hardness values shall be within the limits specified in Table 1.

Hardness of bolts is checked on the head; for nuts, on the end face or flats. The hardness measurement method is chosen by the manufacturer.

6.15 The depth of the decarburized layer is measured on a microsection. The total decarburization depth shall not exceed 1/2 of the nominal thread profile height at the crest and 1/10 of the nominal thread profile height at the root (Figure 4).

1 - fully or partially decarburized zone;

2 - non-decarburized zone

Figure 4

6.16 Mechanical properties of bolt and nut blanks shall conform to the technical requirements for the material from which the product is made.

Control of blanks manufactured by free forging is carried out in accordance with GOST 8479.

7 TRANSPORTATION AND STORAGE

Temporary corrosion protection of products, packaging, package marking, transportation and storage - in accordance with GOST 18160.

APPENDIX A

(recommended)

DESIGNATION SCHEME FOR BOLTS AND NUTS

The designation of bolts and nuts shall be written according to the following scheme

1 - product name; 2 - product grade A; 3 - design type 2; 4 - nominal thread diameter; 5 - fine thread pitch; 6 - thread direction; 7 - thread tolerance class; 8 - product length (except nuts); 9 - material group designation; 10 - indication of the use of killed (C) or free-cutting (A) steel; 11 - material grade for groups 02, 04, 11, 21; 12 - coating types and thickness

Notes

1 The designation does not indicate:

design 1, coarse thread pitch, right-hand thread, absence of coating, as well as parameters uniquely defined by the standard;

product grade B, if the standard for a specific fastener provides for 2 product grades (A and B).

2 If a coating not covered by this standard is used, its designation shall be given according to GOST 9.306.