In common with shamaliabhavin,

1. I'm wondering why B31.1 used allowable bending stress value as 15.86 MPa for calculated pipe support span at 400 C. I don't know exactly where this value(15.86Mpa)is derived from. Is it just Sh/4 ??

2. whenever we calculate bending stress, It is affected by pipe material, pipe size, section modulus and so on. I think that allowable bending stress is variable factor(ASME B31.1 has only one value in considering maximum pipe span). So How do we get the allowable bending stress for pipe support span?