why is the code allowable for ASME B31.4 - 2012 is different from B31.4-2009 for Stresses Due to Sustained Loads?
According to AutoPIPE help section: Reference Information> Code Compliance Calculations> ASME 31.4 2012>
A. Stresses Due to Sustained Loads allowable:
"AutoPIPE reports Sl, and the allowable stress (0.75×Sy), where Sy is the specified minimum yield strength."
B. According to ASME B31.4 code:
Stress Values for steel pipe during operation shall not exceed the allowable values of table 403.3.1-1 as calculated by this chapter.