Code differences (ASME 31.1 & 31.3) in Pipe wall thickness calculations
ASME B31.1
ASME B31.3
Basic formula to calculate wall thickness is same.
Each code has different Weld Joint efficiency factor (E).
Each code has different Stress range reduction factor (f).
31.3 advise to use Weld joint strength reduction factor for temperatures 511 & above.
31.3 defines the design pressure & design temperature as:
The most severe coincident pressure & temperature for which greatest thickness or
highest component rating is required.
31.1 defines the design pressure & design temperature as:
The design temperature shall be assumed to be the same as the fluid temperature and
the internal design pressure shall be not less than the maximum sustained operating
pressure (MSOP) within the piping system including the effects of static head.