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U.S. Bolts: Tensile Strength & Proof Load Specifications

Tensile strength and proof loads SAE bolts.

  • Proof Load - is the maximum tensile force that can be applied to a bolt that will not result in plastic deformation
  • Clamp load - equals to 75% of proof load

U.S. Bolts - Coarse Threads

Proof Load

U.S. Bolts Coarse Threads - Proof Loads
Nom Bolt Size
(in)		Grade
258Lamalloy
Proof Load (lbf)
1/4 1750 2700 3800 4600
5/16 2900 4450 6300 7600
3/8 4250 6600 9300 11250
7/16 5850 9050 12800 15400
1/2 7800 12100 17000 20600
9/16 10000 15500 21800 26400
5/8 12400 19200 27100 32750
3/4 18400 28400 40100 48500
7/8 15200 39300 55400 67000
1 20000 51500 72700 87900
1 1/8 25200 56500 91600 110700
1 1/4 32000 71700 116300 140500
1 3/8 38100 85500 138600 167500
1 1/2 46400 104000 168600 203700

Clamp Load

U.S. Bolts Coarse Threads - Clamp Loads
Nom Bolt Size
(in)		Grade
258Lamalloy
Clamp Load (lbf)
1/4 1313 2025 2850 3450
5/16 2175 3338 4725 5700
3/8 3188 4950 6975 8438
7/16 4388 6788 9600 11550
1/2 5850 9075 12750 15450
9/16 7500 11625 16350 19800
5/8 9300 14400 20325 24563
3/4 13800 21300 30075 36375
7/8 11400 29475 41550 50250
1 15000 38625 54525 65925
1 1/8 18900 42375 68700 83025
1 1/4 24000 53775 87225 105375
1 3/8 28575 64125 103950 125625
1 1/2 34800 78000 126450 152775

US Bolts Coarse Threads - Proof Loads

U.S. Bolts - Fine Threads

Proof Load

U.S. Bolts Fine Threads - Proof Loads
Nom Bolt Size
(in)		Grade
258Lamalloy
Proof Load (lb)
1/4 2000 3100 4350 5280
5/16 3200 4900 6950 8410
3/8 4800 7450 10500 12730
7/16 6550 10100 14200 17200
1/2 8800 13600 19200 23200
9/16 11200 17300 24400 29450
5/8 14100 21800 30700 37100
3/4 20500 31700 44800 54100
7/8 16800 43300 61100 73800
1 21900 56400 79600 96200
1 1/8 28200 63350 102700 124100
1 1/4 35400 79400 128800 155600
1 3/8 43400 97300 157800 190700
1 1/2 52200 117000 189700 229200

Clamp Load

U.S. Bolts Fine Threads - Clamp Loads
Nom Bolt Size
(in)		Grade
258Lamalloy
Clamp Load (lb)
1/4 1500 2325 3263 3960
5/16 2400 3675 5213 6308
3/8 3600 5588 7875 9548
7/16 4913 7575 10650 12900
1/2 6600 10200 14400 17400
9/16 8400 12975 18300 22088
5/8 10575 16350 23025 27825
3/4 15375 23775 33600 40575
7/8 12600 32475 45825 55350
1 16425 42300 59700 72150
1 1/8 21150 47513 77025 93075
1 1/4 26550 59550 96600 116700
1 3/8 32550 72975 118350 143025
1 1/2 39150 87750 142275 171900
  • Grade 2 - Low Carbon Steel - up to 3/4" proof load 55000 psi, minimum tensile strength 74000 psi - 3/4" - 1/1/2" proof load 33000 psi, minimum tensile strength 66000 psi
  • Grade 5 - Medium Carbon Steel, Quenched and Tempered - up to 1" proof load 85000 psi - 1" - 1/1/2" proof load 74000 psi, minimum tensile strength 105000 psi
  • Grade 8 - Medium Carbon Alloy Steel, Quenched and Tempered - up to 1 1/2" proof load 120000 psi, minimum tensile strength 150000 psi
  • Lamalloy - Medium Carbon Alloy Steel, Quenched and Tempered - up to 1 1/2" proof load 145000 psi, minimum tensile strength 180000 psi
  • 1 psi = 6.9 kPa

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