The governing code for the pipe stress analysis is generally ASME B31.3[1] and 31.

Underground or buried piping (or Pipeline) is all piping that runs below grade. In every process industry, there will be few lines (Sewer or drainage system, Sanitary, and Storm Water lines, Firewater or drinking water lines, etc), part of which normally runs underground. However the term buried piping or underground piping, in a true sense, appears for the pipeline industry as miles of long pipe run carrying fluids will be there.