SA193-B7M > 2 1/2"

[codeeng]

We have an application where we would like to use 2 3/4" studs. Is anyone aware of any relaxation for use on a Div 1 vessel. Thanks in advance.

 

[metengr]

Yes, refer to the 2004 Edition of ASME B31.3, Appendix A, Table A-2 page 194, for Grade 193 B7M bolting; the allowable stress values are applicable to 4" and under.

 

[codeeng]

Thanks meteng, but how does this equate with Section IID which only goes up to 2 1/2".

 

[metengr]

codeeng;
I figured you would probably respond rather quickly with the answer I provided. Before elaborating, I should have probably prefaced my answer with a question - where exactly are the studs going to be used in the pressure vessel? If the studs are to be used in a horizontal or vertical flange that is a direct part of the pressure vessel (it is designed for exposure to direct pressure), the answer is Section VIII, Div 1 for bolting follows the specific requirements in Section II, Part D (which limits your use at 2.5" and under).

If the studs are used external to the pressure vessel - like a nozzle flange or appurtance flange, you can refer to one of the B31 Piping Codes for guidance.

 

[codeeng]

They're on the vessel proper, not part of piping.