Tightening torque vs clamp load

Suggested Starting Values

The below estimated torque calculations are only offered as a guide. Use of its content by anyone is the sole responsibility of that person and they assume all risk.

 

Due to many variables that affect the torque-tension relationship like human error, surface texture, and lubrication the only way to determine the correct torque is through experimentation under actual joint and assembly conditions.

 

ASTM A307

Bolt SizeTPIProof Load (lbs)1Clamp Load (lbs)2Tightening Torque (ft-lbs)
Galv+WaxedGalvPlain
14201,053790243
516181,7351,302387
38162,5671,92561512
716143,5212,640102419
12134,7003,525153729
916126,0284,521215342
58117,4855,614297358
341011,0628,29752130104
78915,30111,47684209167
1820,07115,053125314251
118725,27118,953178444355
114732,09324,070251627501
138638,25428,690329822657
112646,53434,9004361,091873
134562,92847,1966881,7211,377
241282,80062,1001,0352,5882,070
214412107,64080,7301,5143,7843,027
2124132,48099,3602,0705,1254,140
2344163,282122,4612,8067,0165,613
34197,726148,2953,7079,2687,415
3144235,152176,3644,77711,9419,553
3124275,890206,9176,03515,08812,070
3344319,939239,9547,49918,74614,997
44366,970275,2279,17422,93618,348

SAE Grade 2

Bolt SizeTPIProof Load (lbs) 1Clamp Load (lbs) 2Tightening Torque (ft-lbs)
Galv+WaxedGalvPlain
14201,7501,313375
516182,9002,17561411
38164,2503,188102520
716145,8504,388164032
12137,8005,850246149
9161210,0007,500358870
581112,4009,3004812197
341018,40013,80086216173
78915,20011,40083208166
1820,00015,000125313250
118725,20018,900177443354
114732,00024,000250625500
138638,10028,575327819655
112646,40034,8004351,088870

ASTM A325

Bolt SizeTPITensionTightening Torque Range (ft-lbs) (Min – Max)
MinMaxGalv+WaxedPlain
121312,00014,00050 – 58100 – 117
581119,00023,00099 – 120198 – 240
341028,00034,000175 – 213350 – 425
78939,00047,000284 – 343569 – 685
1851,00061,000425 – 508850 – 1,017
118764,00077,000600 – 7221,200 – 1,444
114781,00098,000844 – 1,0211,687 – 2,042
138697,000117,0001,111 – 1,3412,223 – 2,681
1126118,000143,0001,475 – 1,7882,950 – 3,575

ASTM A449 / SAE Grade 5*

Bolt SizeTPIProof Load (lbs) 1Clamp Load (lbs) 2Tightening Torque (ft-lbs)
Galv+WaxedGalvPlain
14202,7002,0254118
516184,4503,33892217
38166,6004,950153931
716149,0506,788256249
121312,0509,038389475
9161215,45011,58854136109
581119,20014,40075188150
341028,40021,300133333266
78939,25029,438215537429
1851,50038,625322805644
118756,45042,338397992794
114771,70053,7755601,4001,120
138685,45064,0887341,8361,469
1126104,00078,0009752,4381,950
1345104,50078,3751,1432,8572,286
2412137,500103,1251,7194,2973,438
214412178,750134,0632,5146,2845,027
2124220,000165,0003,4388,5946,875
2344271,150203,3634,66011,6519,321
34328,350246,2636,15715,39112,313
* SAE J429 grade 5 bolts do not exceed 1-1/2″ diameter.

ASTM A193 B7 / ASTM A320 L7 / ASTM A354 BC

Bolt SizeTPIProof Load (lbs) 1Clamp Load (lbs) 2Tightening Torque (ft-lbs)
Galv+WaxedGalvPlain
14203,3502,51351310
516185,5004,125112721
38168,1506,113194838
7161411,1508,363307661
121314,90011,1754711693
9161219,10014,32567168134
581123,75017,81393232186
341035,05026,288164411329
78948,50036,375265663530
1863,65047,738398995796
118780,10060,0755631,4081,126
118882,93462,2015831,4581,166
1147101,75076,3137951,9871,590
1148105,00678,7548202,0511,641
1386121,30090,9751,0422,6062,085
1388129,49297,1191,1132,7822,226
1126147,550110,6631,3833,4582,767
1128156,687117,5151,4693,6722,938
1345199,500149,6252,1825,4554,364
1348218,400163,8004,778
2412262,500196,8753,2818,2036,563
28290,850218,1387,271
214412341,250255,9384,79911,9979,598
2148373,801280,35110,513
2124420,000315,0006,56316,40613,125
2128466,200349,65014,569
2344468,500351,2638,05020,12416,100
2348515,851386,88817,732
34567,150425,36310,63426,58521,268
38618,451463,83823,192
3144674,500505,87513,70134,25227,402
3148730,550547,91329,679
3124791,350593,51317,31143,27734,622
3128851,201638,40137,240
334491770068827521,50953,77143,017
3348982,300736,72546,045
44105260078945026,31565,78852,630
481,121,950841,46356,098

ASTM A490

Bolt SizeTPITension (lbs)Tightening Torque Range (ft-lbs) (Min – Max)
MinMaxPlainLubricated
121315,00018,000125 – 15063 – 75
581124,00029,000250 – 302125 – 151
341035,00042,000438 – 525219 – 263
78949,00059,000715 – 860357 – 430
1864,00077,0001,067 – 1,283533 – 642
118780,00096,0001,500 – 1,800750 – 900
1147102,000122,0002,125 – 2,5421,063 – 1,271
1386121,000145,0002,773 – 3,3231,386 – 1,661
1126148,000178,0003,700 – 4,4501,850 – 2,225

ASTM A354-BD / SAE Grade 8*

Bolt SizeTPIProof Load (lbs) 1Clamp Load (lbs) 2Tightening Torque (ft-lbs)
PlainLubricated
14203,8002,850126
516186,3004,7252512
38169,3006,9754422
7161412,7509,5637035
121317,05012,78810753
9161221,85016,38815477
581127,10020,325212106
341040,10030,075376188
78955,45041,588606303
1872,70054,525909454
118791,55068,6631,287644
1147120,00090,0001,875938
1386138,600103,9502,3821,191
1126168,600126,4503,1611,581
1345228,000171,0004,9882,494
2412300,000225,0007,5003,750
214412390,000292,50010,9695,484
2124480,000360,00015,0007,500
2344517,650388,23817,7948,897
34626,850470,13823,50711,753
3144745,500559,12530,28615,143
3124874,650655,98838,26619,133
33441,014,300760,72547,54523,773
441,163,400872,55058,10029,085
* SAE J429 grade 8 bolts do not exceed 1-1/2″ diameter.