Operating Case vs Sustained Case (Hoop Stress)

Good Morning.

I made an analysis for preinsulated burried piping as per ASME B31.3;I have a question regarding hoop stress. Why is that the result of Operating Case (W+T1+P1) is different from Sustained Case (W+P1) with regards to the HOOP STRESS considering they have the same pressure (P1) applied?

Thank you very much for the help. Greatly appreciate it.

Corrosion.

Regards,

sorry..what do u mean "corrosion"?

to what i understand the formula for sustained hoop stress is S=Pd/2t...but with how about for operating hoop stress which involves TEMPERATURE?

thanks

I think that you have now the answer:

http://65.57.255.42/ubbthreads/ubbthreads.php?ubb=showflat&Number=41684#Post41684

Regards,