Specification Library

Suggested Assembly Torque Values to Produce Corresponding Bolt Loads

Size Tensile
Stress Area
AS
Square Inch
SA193 & ASTM 193 B7 Studs with
A194 2H Heavy Hex Nuts
Clamp Load
P. Lbs.
Tightening Torque
Dry Lubed
K= .223
Ft. Lbs.
K= .167
Ft. Lbs.
1/2 – 13 0.138 10,350 96 72
9/16 – 12 0.177 13,275 139 104
5/8 – 11 0.220 16,500 192 143
3/4 – 10 0.327 24,525 342 256
7/8 – 9 0.452 33,900 551 413
1 – 8 0.594 44,550 828 620
1-1/8 – 8 0.776 58,200 1217 911
1-1/4 – 8 0.984 73,800 1714 1284
1-3/8 – 8 1.215 91,125 2328 1744
1-1/2 – 8 1.471 110,325 3076 2303
1-5/8 – 8 1.769 132,675 4006 3000
1-3/4 – 8 2.06 154,500 5024 3763
1-7/8 – 8 2.41 180,750 6298 4716
2 – 8 2.74 205,500 7638 5720
2-1/4 – 8 3.52 264,000 11,038 8266
2-1/2 – 8 4.40 330,000 15,331 11,481
Size SA193 & ASTM 193 B7M Studs with
A194 2HM Heavy Hex Nuts
Clamp Load
P. Lbs.
Tightening Torque
Dry Lubed
K= .223
Ft. Lbs.
K= .167
Ft. Lbs.
1/2 – 13 7,866 73 55
9/16 – 12 10,089 105 79
5/8 – 11 12,540 146 109
3/4 – 10 18,639 260 194
7/8 – 9 25,764 419 314
1 – 8 33,858 629 471
1-1/8 – 8 44,232 925 692
1-1/4 – 8 56,088 1303 976
1-3/8 – 8 69,255 1770 1325
1-1/2 – 8 83,847 2337 1750
1-5/8 – 8 100,833 3045 2280
1-3/4 – 8 177,420 3818 2860
1-7/8 – 8 137,370 4786 3584
2 – 8 156,180 5805 4347
2-1/4 – 8 200,640 8389 6282
2-1/2 – 8 250,800 11,652 8726
Size Tensile
Stress Area
AS
Square Inch
SA320 & ASTM A320 L7 Studs with
A194 Grade 7L Heavy Hex Nuts
Clamp Load
P. Lbs.
Tightening Torque
Dry Lubed
K= .223
Ft. Lbs.
K= .167
Ft. Lbs.
1/2 – 13 0.138 10,350 96 72
9/16 – 12 0.177 13,275 139 104
5/8 – 11 0.220 16,500 192 143
3/4 – 10 0.327 24,525 342 256
7/8 – 9 0.452 33,900 551 413
1 – 8 0.594 44,550 828 620
1-1/8 – 8 0.776 58,200 1217 911
1-1/4 – 8 0.984 73,800 1714 1284
1-3/8 – 8 1.215 91,125 2328 1744
1-1/2 – 8 1.471 110,325 3076 2303
1-5/8 – 8 1.769 132,675 4006 3000
1-3/4 – 8 2.06 154,500 5024 3763
1-7/8 – 8 2.41 180,750 6298 4716
2 – 8 2.74 205,500 7638 5720
2-1/4 – 8 3.52 264,000 11,038 8266
2-1/2 – 8 4.40 330,000 15,331 11,481
Size SA320 & ASTM A320 L7M Studs with
A194 7ML Heavy Hex Nuts
Clamp Load
P. Lbs.
Tightening Torque
Dry Lubed
K= .223
Ft. Lbs.
K= .167
Ft. Lbs.
1/2 – 13 7,866 73 55
9/16 – 12 10,089 105 79
5/8 – 11 12,540 146 109
3/4 – 10 18,639 260 194
7/8 – 9 25,764 419 314
1 – 8 33,858 629 471
1-1/8 – 8 44,232 925 692
1-1/4 – 8 56,088 1303 976
1-3/8 – 8 69,255 1770 1325
1-1/2 – 8 83,847 2337 1750
1-5/8 – 8 100,833 3045 2280
1-3/4 – 8 177,420 3818 2860
1-7/8 – 8 137,370 4786 3584
2 – 8 156,180 5805 4347
2-1/4 – 8 200,640 8389 6282
2-1/2 – 8 250,800 11,652 8726

NOTES:
1. Tightening torque values from the formula T=KDP, where T = tightening torque,
lb. ft. K – torque friction coefficient, D = nominal bolt diameter, in.; and P = bolt
clamping load developed by tightening, lb.
2. Clamp load is also known as preload or initial load in tension on bolt. Clamp load
(lb.) is calculated by arbitrarily assuming useable bolt strength is 75% of bolt
proof load (PSI) times the stress area (sq. in.) of threaded section of each bolt
size. Higher or lower values of clamp load can be used depending on the
application requirements and the judgement of the designer.
3. No proof load has been established by ASTM. Value shown in table are assumed
at 95% of yield strength.