150lb Flange Pressure Capability

[hershey28]

Can't find data showing pressure capability of Class 150 steel weldneck flange. Not concerned about pressure vs. temp, but, rather pressure vs. bolt torque.

I want to use 150lb flanges in an application where system pressure MAY reach 500 psig, normal operating range will be less than 100 psig. Gasket choice will sustain the pressure. Question is, can I torque the flanges to handle this pressure?

 

[RossABQ]

The contractor is bound to ask if there is a way around this situation, it is obviously of great financial importance to him. He would be stupid not to ask. But it is your duty as a professional to tell him the work is unacceptable and not in conformance with the contract documents. He'll get over it!