Allowable stresses for the materials specifications contained in the piping class have been established in line with ANSI/ASME B31.3, Paragraph 302.3.
For API 5L Grade B, a distinction has been made between seamless pipe and welded pipe with a weld joint factor E=0.95 (in accordance with ANSI/ASME B31.3, Table 302.4). For all other materials, the selection of pipe wall thickness is based on allowable internal pressure calculations for seamless pipe only. Consequently, where welded pipe is used, a weld joint factor of 1 should be guaranteed.
In accordance with ANSI/ASME B31.3, Paragraph 302.2.2, not more than 87.5% of the nominal wall thickness has been used in calculations for butt welding fittings.