For completeness,
What are the correct buttons to press when limiting all pipe stress to below yield?
The glass lined pipework i am reviewing cannot accept any yielding of the CS pipe base.
As Sh =2/3 Sy, and OCC=1.33Sh,
Then if i run a operating case using (occ) for
the load, then am i right?
If you use OCC for an operating case it certainly will be confusing for whoever would happen across your work after the fact.
Why not simply run the correct B31 code cases and limit your stresses across the board to be less than yield?
TJN,
The use of "conservative allowable" for stress design will avoid the case of yielding material.
Will the glass lining have cracking problems before the carbon steel approaches yield? There might be a strain limit for the glass lining. It might be advisable to use some value of allowable stress approximately that of the glass material. Even then the point loads at support locations could cause cracking of the glass lining, while overall stresses could be within allowables.
I would be very surprised if you could run your glass lined pipe anywhere near to the yield stress of the CS pipe. It's been a good while since I've had to suffer through a glass lined system, but I seem to remember having to limit bending stresses to more along the lines of 5000 psi in order ot keep the glass lining from cracking.
I second Edwards Experience!