GOST 7786-81 Countersunk Square Shoulder Bolts, Product Grade C. Construction and Dimensions

Countersunk square shoulder bolts, product grade C. Construction and dimensions.

This standard applies to countersunk square shoulder bolts with nominal thread diameter from 5 to 20 mm. Corresponds to ST SEV 2325-80.

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

COUNTERSUNK SQUARE SHOULDER BOLTS, PRODUCT GRADE C Construction and dimensions Countersunk square shoulder bolts, product grade C. Construction and dimensions	GOST 7786-81* (ST SEV 2325-80) Supersedes GOST 7786-72

Example of designation for a bolt with thread diameter d = 12 mm, coarse thread pitch with tolerance field 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 7786-81

Nominal thread diameter d		5	6	8	10	12	16	20
Head diameter D		9	11	14	18	23	28	35
Head and shoulder height k ( js 16)		4	5	6	8	10	12	15
Side of square shoulder V		5	6	8	10	12	16	20
Thread length b	For l ≤ 120	16	18	22	26	30	38	46
	For l > 120	-	-	-	32	36	44	52

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

Tolerances and methods for checking 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 shank portion d₁ is approximately equal to the pitch diameter or the nominal thread diameter.

Technical requirements — per GOST 1759.0-87. Mechanical properties of bolts shall conform to property classes 3.6, 4.6, 4.8, 5.6, 5.8 and 8.8.

Theoretical mass is given in the reference appendix.

Bolt length l	Nominal thread diameter d
	5	6	8	10	12	16	20
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 manufactured with lengths between the bold lines. 2. Bolts in the range from the upper bold line to the dashed line are manufactured with thread up to the shoulder.

Bolt length, l, mm	Theoretical mass of 1000 pcs of bolts, kg, at nominal thread diameter d, mm
	5	6	8	10	12	16	20
20	2 , 908	-	-	-	-	-	-
25	3.498	5.240	9.66	16.40	-	-	-
30	4.080	6.086	11.20	18.84	30.19	-	-
35	4 , 678	6.932	12.74	21.28	33.73	-	-
40	5.268	7.777	14.28	23.72	37.27	71.71	-
45	5.859	8.621	15.81	26.16	40.81	78.04	-
50	6.448	9.466	17.35	28.61	44.35	84.37	131.7
55	7.038	10.311	18.89	31.05	47.89	91.09	141.9
60	7.628	11.156	20.43	33.49	51.43	97.62	152.1
65	8.218	12 , 001	21.97	35.93	54.97	104.15	162.3
70	8.808	12.845	23.51	38.38	58.51	110.67	172.6
75	9.399	13.690	25.05	40 ,82	62.05	117.20	182.8
80	9.989	14.535	26.59	43.26	65.59	123.73	193.1
90	-	16.225	29.67	48.27	72.67	136.78	213.5
100	-	-	32.75	56.08	79.75	149.84	234.0
110	-	-	-	58.04	86.83	162.89	254.5
120	-	-	-	62.92	93.91	175.94	274.9
130	-	-	-	67.81	100.99	188.10	295.4
140	-	-	-	72.69	108.07	202.05	315.9
150	-	-	-	77.58	115.15	215.11	336.3
160	-	-	-	-	122.23	228.16	356.8
170	-	-	-	-	129.31	241.21	377.3
180	-	-	-	-	136.39	254.26	397.7
190	-	-	-	-	143.47	267.31	418.2
200	-	-	-	-	150.55	280.36	438.7

Corresponds to DIN 605, DIN 608.