New EEMUA guidance on PWHT for P1 steels

12 February 2019

The removal of mandatory Post Weld Heat Treatment (PWHT) for P1 group CMn steels thicker than 0.75 inch in the 2014 edition of ASME B31.3 (and later editions) prompted EEMUA to develop new guidance, now published as EEMUA 235, Guidance on PWHT for P1 CMn Steels.

If PWHT is performed incorrectly, or neglected altogether, residual stresses can combine with load stresses to exceed a material’s design limitations. This can lead to weld failures, higher cracking potential and increased susceptibility to brittle fracture.

EEMUA 235 provides guidance to designers of piping systems on the threshold thickness for PWHT of P1 steels. It also advises on the benefit of PWHT for P1 steels when selected for low temperature applications, such as in the offshore oil and gas sector.

EEMUA commissioned fracture mechanics specialists to create a new set of design curves for P1 steels based on ASME B31.3 and API 579, which are included in the new publication.

EEMUA 235 (Edition 1) is available to purchase as digital and print editions directly from EEMUA through the on-line Shop.

Employees of EEMUA Member companies can download a complimentary digital edition from the online Knowledge Centre, and employees of EEMUA Associate companies can purchase digital and printed copies at a discounted price from the Shop.