Standard bolt torque specifications¶

How to determine bolt strength¶

Bolt	Mark	Class
Hexagon head bolt	Bolt head No. 4 – 11	4T – 11T
Hexagon head bolt	No mark	4T
Hexagon flange bolt w/ washer hexagon bolt	No mark	4T
Hexagon head bolt	Two protruding lines	5T
Hexagon flange bolt w/ washer hexagon bolt	Two protruding lines	6T
Hexagon head bolt	Three protruding lines	7T
Hexagon head bolt	Four protruding lines	8T
Stud bolt	No mark	4T
Stud bolt	Grooved	6T
Welded bolt	—	4T

Class	Diameter mm	Pitch mm	Head bolt kg-cm	Head bolt ft-lb	Head bolt N·m	Flange bolt kg-cm	Flange bolt ft-lb	Flange bolt N·m
4T	6	1	55	48 in.-lb	5	60	52 in.-lb	6
4T	8	1.25	130	9	12.5	145	10	14
4T	10	1.25	260	19	26	290	21	29
4T	12	1.25	480	35	47	540	39	53
4T	14	1.5	760	55	74	850	61	84
4T	16	1.5	1,150	83	115	—	—	—
5T	6	1	65	56 in.-lb	6.5	75	65 in.-lb	7.5
5T	8	1.25	160	12	15.5	175	13	17.5
5T	10	1.25	330	24	32	360	26	36
5T	12	1.25	600	43	59	670	48	65
5T	14	1.5	930	67	91	1,050	76	100
5T	16	1.5	1,400	101	140	—	—	—
6T	6	1	80	69 in.-lb	8	90	78 in.-lb	9
6T	8	1.25	195	14	19	210	15	21
6T	10	1.25	400	29	39	440	32	44
6T	12	1.25	730	53	71	810	59	80
6T	14	1.5	1,100	80	110	1,250	90	125
6T	16	1.5	1,750	127	170	—	—	—
7T	6	1	110	8	10.5	120	9	12
7T	8	1.25	260	19	25	290	21	28
7T	10	1.25	530	38	52	590	43	58
7T	12	1.25	970	70	95	1,050	76	105
7T	14	1.5	1,500	108	145	1,700	123	165
7T	16	1.5	2,300	166	230	—	—	—
8T	8	1.25	300	22	29	330	24	33
8T	10	1.25	620	45	61	690	50	68
8T	12	1.25	1,100	80	110	1,250	90	120
9T	8	1.25	340	25	34	380	27	37
9T	10	1.25	710	51	70	790	57	78
9T	12	1.25	1,300	94	125	1,450	105	140
10T	8	1.25	390	28	38	430	31	42
10T	10	1.25	800	58	78	890	64	88
10T	12	1.25	1,450	105	140	1,600	116	155
11T	8	1.25	430	31	42	480	35	47
11T	10	1.25	890	64	87	990	72	97
11T	12	1.25	1,600	116	155	1,800	130	175