GOST 7801-81 Increased Cup Nibbed Head Bolts, Product Grade C. Construction and Dimensions

GOST 7801-81 applies to increased cup nibbed head bolts, product grade C, with nominal thread diameter from 6 to 20 mm.

The construction and dimensions of the bolts shall conform to those shown in the drawing and in Tables 1 and 2.

Table 1

mm

INCREASED CUP NIBBED HEAD BOLTS, PRODUCT GRADE C Construction and dimensions Increased cup nibbed head bolts, product grade C. Construction and dimensions	GOST 7801-81* Supersedes GOST 7801-72

Example of a designation for a bolt with thread diameter d = 12 mm, coarse thread pitch, tolerance class 8g, length l = 60 mm, property class 3.6, with zinc coating 6 µm thick applied by cathodic reduction, chromated:

Bolt M12×60.36.016 GOST 7801-81

Table 2

mm

Nominal thread diameter d		6	8	10	12	16	20
Head diameter D		14	18	23	28	35	44
Head height k		3	4	5	6	8	10
Sphere radius R »		11	14	18	22	26	32
Nib height W, not less than		3	3.5	5	6	8	9
Thread length b	For l ≤ 120	18	22	26	30	38	46
	For l > 120	-	-	32	36	44	52

Thread — per GOST 24705-81, thread pitch — coarse. Thread runout and incomplete thread — per GOST 27148-86. Bolt ends — per GOST 12414-66.

Radius under head — per GOST 24670-81.

Tolerances and methods for inspecting dimensions and deviations of form and location of surfaces — per GOST 1759.1-82.

By agreement between the manufacturer and the customer, bolts may be made with thread tolerance class 6e.

Surface defects and inspection methods — per GOST 1759.2-82.

The diameter of the plain part of the shank d₁ is approximately equal to the pitch diameter of the thread or equal to the nominal thread diameter.

Technical requirements — per GOST 1759.0-87. The mechanical properties of the bolts shall conform to property classes 3.6, 4.6, 4.8, 5.6 and 5.8.

The theoretical mass of bolts is given in the reference appendix.

Appendix

For reference

Bolt length l	Nominal thread diameter d
	6	8	10	12	16	20
25		-	-	-	-	-
30			-	-	-	-
35				-	-	-
40						-
45						-
50						-
55
60
65
70
75
80
90
100
110	-
120	-
130	-
140	-
150	-
160	-	-
170	-	-
180	-	-
190	-	-
200	-	-
Notes: 1. Bolts are made with lengths between the bold lines. 2. Bolts in the range from the upper bold line to the dashed line are made with thread up to the nib.

Bolt length l, mm	Theoretical mass of 1000 pcs of bolts, kg, at nominal thread diameter d, mm
	6	8	10	12	16	20
25	6.501	-	-	-	-	-
30	7.346	14.34	-	-	-	-
35	8.191	15.88	27.16	-	-	-
40	9.035	17.42	29.87	46.53	90.15	-
45	9.880	18.95	32.32	50.08	96.67	-
50	10.725	20.48	34.76	53.62	103.20	-
55	11.570	22.03	37.20	57.16	109.73	188.2
60	12.415	23.57	39.64	60.70	116.25	198.5
65	13.260	25.11	42.08	64.24	122.78	208.7
70	14.105	26.65	44.53	67.78	129.31	219.0
75	14.950	28.19	46.97	71.32	135.83	229.2
80	15.795	29.73	49.41	74.86	142.36	239.5
90	17.484	32.80	54.30	81.94	155.42	259.9
100	19.174	35.89	59.19	89.01	168.47	280.4
110	-	38.97	64.06	96.09	181.52	300.9
120	-	42.04	68.95	103.17	194.58	321.3
130	-	45.12	73.83	110.25	207.63	341.8
140	-	48.20	78.72	117.33	220.69	362.3
150	-	51.28	83.60	124.41	233.74	382.7
160	-	-	88.49	131.49	246.79	403.2
170	-	-	93.37	138.57	259.85	422.9
180	-	-	98.25	145.65	272.90	443.4
190	-	-	103.14	152.73	285.95	463.8
200	-	-	108.02	159.81	299.01	484.3

Corresponds to DIN 607.