Problem:

What is the significance of Bending Stresses in ASME B31.1 2018?

Solution:

Piping component should meet the requirement given in the equation (15), (16) & (17) from ASME B31.1 to qualify in stress analysis.

Equation (15) gives requirement for Longitudinal stress due to pressure, weight, and other sustained loads (S_L) as follows,

Here, M_A = resultant moment loading on cross section due to weight and other sustained loads, in.-lb (mm-N) (see para. 104.8.4).

First part of longitudinal stress is pressure stress and second part is bending stress.

For example, For Node Number A57 code stresses are as follows,

Find below manual calculations with same design conditions and moments,

As results are matching you can see the effect of bending stress on the longitudinal stress calculation.