Dear Pip-Ers,

I am planning to Use S-80 TEE in a S-40 piping system. B31.3, Appendix D, Note (3) says that "T - Nominal wall thickness of matching pipe".

My questions are

1. What is matching pipe thickness?

2. Shall I use increased thickness (S-80) for both "SIF" and "Section modulus" calculation?

or

3. Shall I use increased thickness (S-80) only for "SIF" Computation and nominal pipe thickness (S-40) for "Section modulus" computation?

Please advise me to solve this issue.

Thanks in advance.