L51650 The Significance of Local Hard Zones on the Outside of Pipeline Girth Welds-Further Studies

In an earlier project it was demonstrated that it may be permissible to relax the NACE MR-01-75 (2) hardness restriction of 22HRC maximum for regions of a pipeline girth weld that are not in direct contact with H2S-containing environments. The objective of this report is to provide quantitative data on which permissible relaxations in hardness limits for external local hard zones in pipelines designed for sour service can be made. This report presents additional data to supplement that obtained in a previous PRCI project conducted at TWI. Further pipe materials with differing pipe wall thickness have been welded, exposed to an internal H2S containing environment and examined for sulphide stress corrosion cracking (SSCC).