Lubricated Bolts and Reduced Torque

Lubrication effect on bolt tension and torque. Calculate the reduced torque required for lubricated bolts compared to dry bolts.

LubricantTorque Reduction (%)
Graphite50 - 55
White Grease35 - 45
SAE 30 oil35 - 45
SAE 40 oil30 - 40
No lube0
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Lubricated Bolt Torque-- lbf ft

Example - Reduction of Torque when Bolt is Lubricated

The maximum tightening torque for a slightly lubricated 1" Grade 5 coarse bolt is 483 lbf ft. Dry bolt torque is approximately 30% higher - or 628 lbf ft.

Tdry = (483 lbf ft) (1 + (30%) / (100%))

= 628 lbf ft

If the bolt is lubricated with SAE 30 oil - the torque compared to a dry bolt is reduced with approximately 40%.

TSAE30 = (628 lbf ft) (1 - (40%) / (100%))

= 377 lbf ft

Note: If torque specified for a dry or slightly oiled bolt is applied to a lubricated bolt - the bolt may overload and break.

Lubricated Bolts and Reduced Torque | MEPKit Engineering Tools | MEPKit