ASME PCC-1 Table O-8 75 ksi max allowable bolt stress

[soletto]

Hallo,

can anyone explain me how the 75 ksi max allowable bolt stress been calculated or how it is derived?

I do know the 172 allowable form ASME II Part D but dont understand the 75 ksi in the table

Thank you BR Stefan

 

[GD2]

Soletto,

Simple. ASME II Part D gives the Max allowable stress for ONLY the bolt material, whereas ASME PCC-1 table gives the ASSEMBlY Bolt stress that takes into account the allowable stresses for flange (without bending) and gasket (without exceeding the max compressive stress).
In other words, when you make a joint with different materials with different stress values, and where you send the muscle man to tighten the joint, you must limit the load on the bolts to protect the other components.

GDD
Canada

 

[BJI]

75 ksi is for the example with B7 bolts, which is about 70% of min specified yield. The actual selection of the 70% maximum is arbitrary, because 75%, 80% or 85% seemed too high for general application. If you refer to section 10, it states that this range can be exceeded for specific cases when assessed by a qualified engineer.

 

[soletto]

yes i was thinking about the 70% of yield stress but i didnt found a formula or a paragraph where this is explained properly...

Thank you!

BR Stefan

 

[r6155]

Try to read actual edition ASME PCC-1 2019
Try to avoid torque, use bolt elongation. Length of stud is not considered in torque value.

Regards