Respected Chuck Becht sir,John Breen sir,Anindya sir,
My query is about Consideration of Hoop stress in Expansion stress but not in sustained stress...
As per B31.3 ,Sustained Longitudinal stress to be compared with Sh....so it is clear that as per code Hoop and radial not to be included in Sustained stress because it is stating"Longitudinal".
and
for Expansion Stress Hoop stress is considered.

please share your opinion in this matter...Why Sustained stresses computation skipped Hoop and Radial stresses..

and Why Hoop stress is considered in computation of Expansion stresses.

Thanks in advance.