Low Strength Bolts

Low strength bolts don’t work well with ASME PCC-1 Appendix O. 

What is wrong with low strength bolts? The low Minimum Permissible Bolt Stress, Sbmin combined with the low Maximum Permissible Bolt Stress, Sbmax creates a nightmare scenario for engineers like me attempting to give bolt torque values to operators assembling flanges in the field. There simply isn’t a bolt torque range that will work.

The biggest issue is that low strength bolts make it difficult to achieve the clamping force required for gasket seating. This is because the Maximum Permissible Bolt Stress, Sbmax is too low to ever meet an acceptable Selected Assembly Bolt Stress, Sbsel in the (O-7) equation for achieving the Minimum Gasket Assembly Seating Stress, Sgmin-s. Gaskets that do not meet the Minimum Gasket Assembly Seating Stress, Sgmin-s are considered improperly seated and represent a major source of leaks in flanges. Please consider replacing your low strength bolts with high strength bolts at your next turnaround.

Unsure if low strength bolts are controlling your PCC-1 Appendix O results? Metalmark Engineering loves checking your PCC-1 Appendix O calculations to determine the source of leaky flanges.