L51651 The Effect of Weld Metal Matching on Girth Weld Performance-Volume 1-A General Literature Review

Over the last decade, a number of recognised – but non-mandatory – Fitness-for-Purpose (FfP) or Engineering Critical Assessment (ECA) codes have become available which allow establishment of tolerable defect sizes in line pipe girth welds. Conceptually, the philosophy of an ECA/FFP defect assessment is torelate the operating stresses, the defect geometry (length and depth), the mechanical and toughness properties of the defected region. In deriving tolerable girth weld defect sizes, an optimized analysis is made in order to ensure that the calculated defect size is tolerable both from a (brittle/unstable) fracture and stable (plastic collapse) failure viewpoint. This report, the first in a three volume series (see also L51685 and L51711), summarizes the assumptions and limitations of currently used fitness-for-purpose based defect analysis methods. The focus is on the effect of differences between pipe and weld metal yield strengths on the capabilities of the PD 6493, WES 2805, API 1104, CSA Z184, and BS 4515 girth weld defect acceptance fitness-for-purpose analysis methods. The investigation also includes case studies to evaluate weld metal yield strength effects on failure behavior.