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
1⁄4201,053790243
5⁄16181,7351,302387
3⁄8162,5671,92561512
7⁄16143,5212,640102419
1⁄2134,7003,525153729
9⁄16126,0284,521215342
5⁄8117,4855,614297358
3⁄41011,0628,29752130104
7⁄8915,30111,47684209167
1820,07115,053125314251
11⁄8725,27118,953178444355
11⁄4732,09324,070251627501
13⁄8638,25428,690329822657
11⁄2646,53434,9004361,091873
13⁄4562,92847,1966881,7211,377
241⁄282,80062,1001,0352,5882,070
21⁄441⁄2107,64080,7301,5143,7843,027
21⁄24132,48099,3602,0705,1254,140
23⁄44163,282122,4612,8067,0165,613
34197,726148,2953,7079,2687,415
31⁄44235,152176,3644,77711,9419,553
31⁄24275,890206,9176,03515,08812,070
33⁄44319,939239,9547,49918,74614,997
44366,970275,2279,17422,93618,348

SAE Grade 2

Bolt SizeTPIProof Load (lbs) 1Clamp Load (lbs) 2Tightening Torque (ft-lbs)
Galv+WaxedGalvPlain
1⁄4201,7501,313375
5⁄16182,9002,17561411
3⁄8164,2503,188102520
7⁄16145,8504,388164032
1⁄2137,8005,850246149
9⁄161210,0007,500358870
5⁄81112,4009,3004812197
3⁄41018,40013,80086216173
7⁄8915,20011,40083208166
1820,00015,000125313250
11⁄8725,20018,900177443354
11⁄4732,00024,000250625500
13⁄8638,10028,575327819655
11⁄2646,40034,8004351,088870

ASTM A325

Bolt SizeTPITensionTightening Torque Range (ft-lbs) (Min – Max)
MinMaxGalv+WaxedPlain
1⁄21312,00014,00050 – 58100 – 117
5⁄81119,00023,00099 – 120198 – 240
3⁄41028,00034,000175 – 213350 – 425
7⁄8939,00047,000284 – 343569 – 685
1851,00061,000425 – 508850 – 1,017
11⁄8764,00077,000600 – 7221,200 – 1,444
11⁄4781,00098,000844 – 1,0211,687 – 2,042
13⁄8697,000117,0001,111 – 1,3412,223 – 2,681
11⁄26118,000143,0001,475 – 1,7882,950 – 3,575

ASTM A449 / SAE Grade 5*

Bolt SizeTPIProof Load (lbs) 1Clamp Load (lbs) 2Tightening Torque (ft-lbs)
Galv+WaxedGalvPlain
1⁄4202,7002,0254118
5⁄16184,4503,33892217
3⁄8166,6004,950153931
7⁄16149,0506,788256249
1⁄21312,0509,038389475
9⁄161215,45011,58854136109
5⁄81119,20014,40075188150
3⁄41028,40021,300133333266
7⁄8939,25029,438215537429
1851,50038,625322805644
11⁄8756,45042,338397992794
11⁄4771,70053,7755601,4001,120
13⁄8685,45064,0887341,8361,469
11⁄26104,00078,0009752,4381,950
13⁄45104,50078,3751,1432,8572,286
241⁄2137,500103,1251,7194,2973,438
21⁄441⁄2178,750134,0632,5146,2845,027
21⁄24220,000165,0003,4388,5946,875
23⁄44271,150203,3634,66011,6519,321
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
1⁄4203,3502,51351310
5⁄16185,5004,125112721
3⁄8168,1506,113194838
7⁄161411,1508,363307661
1⁄21314,90011,1754711693
9⁄161219,10014,32567168134
5⁄81123,75017,81393232186
3⁄41035,05026,288164411329
7⁄8948,50036,375265663530
1863,65047,738398995796
11⁄8780,10060,0755631,4081,126
11⁄8882,93462,2015831,4581,166
11⁄47101,75076,3137951,9871,590
11⁄48105,00678,7548202,0511,641
13⁄86121,30090,9751,0422,6062,085
13⁄88129,49297,1191,1132,7822,226
11⁄26147,550110,6631,3833,4582,767
11⁄28156,687117,5151,4693,6722,938
13⁄45199,500149,6252,1825,4554,364
13⁄48218,400163,800––4,778
241⁄2262,500196,8753,2818,2036,563
28290,850218,138––7,271
21⁄441⁄2341,250255,9384,79911,9979,598
21⁄48373,801280,351––10,513
21⁄24420,000315,0006,56316,40613,125
21⁄28466,200349,650––14,569
23⁄44468,500351,2638,05020,12416,100
23⁄48515,851386,888––17,732
34567,150425,36310,63426,58521,268
38618,451463,838––23,192
31⁄44674,500505,87513,70134,25227,402
31⁄48730,550547,913––29,679
31⁄24791,350593,51317,31143,27734,622
31⁄28851,201638,401––37,240
33⁄4491770068827521,50953,77143,017
33⁄48982,300736,725––46,045
44105260078945026,31565,78852,630
481,121,950841,463––56,098

ASTM A490

Bolt SizeTPITension (lbs)Tightening Torque Range (ft-lbs) (Min – Max)
MinMaxPlainLubricated
1⁄21315,00018,000125 – 15063 – 75
5⁄81124,00029,000250 – 302125 – 151
3⁄41035,00042,000438 – 525219 – 263
7⁄8949,00059,000715 – 860357 – 430
1864,00077,0001,067 – 1,283533 – 642
11⁄8780,00096,0001,500 – 1,800750 – 900
11⁄47102,000122,0002,125 – 2,5421,063 – 1,271
13⁄86121,000145,0002,773 – 3,3231,386 – 1,661
11⁄26148,000178,0003,700 – 4,4501,850 – 2,225

ASTM A354-BD / SAE Grade 8*

Bolt SizeTPIProof Load (lbs) 1Clamp Load (lbs) 2Tightening Torque (ft-lbs)
PlainLubricated
1⁄4203,8002,850126
5⁄16186,3004,7252512
3⁄8169,3006,9754422
7⁄161412,7509,5637035
1⁄21317,05012,78810753
9⁄161221,85016,38815477
5⁄81127,10020,325212106
3⁄41040,10030,075376188
7⁄8955,45041,588606303
1872,70054,525909454
11⁄8791,55068,6631,287644
11⁄47120,00090,0001,875938
13⁄86138,600103,9502,3821,191
11⁄26168,600126,4503,1611,581
13⁄45228,000171,0004,9882,494
241⁄2300,000225,0007,5003,750
21⁄441⁄2390,000292,50010,9695,484
21⁄24480,000360,00015,0007,500
23⁄44517,650388,23817,7948,897
34626,850470,13823,50711,753
31⁄44745,500559,12530,28615,143
31⁄24874,650655,98838,26619,133
33⁄441,014,300760,72547,54523,773
441,163,400872,55058,10029,085
* SAE J429 grade 8 bolts do not exceed 1-1/2″ diameter.