ASME B31.3 Allowable Bolt Stress vs. Required Flange Bolt Preload

[beh188]

I am trying to understand the design intent for the ASME B31.3 allowable bolt stresses when bolts used on flanges.

A company like Flexitallic recomends bolt preload values for spiral wound gaskets around 50,000 psi, but the maximum allowable stress in ASME B31.3 for many bolt materials is 25,000 psi.

Can someone explain the B31.3 code issues when using a preload of 50,000 psi?

 

[SnTMan]

beh188, the differences between allowable bolt stress for DESIGN and actual applied bolt stress at assembly have been discussed numerous times, see the PV forum, maybe you could research previous threads, and come back with further questions.

Regards,

Mike