Guidelines for Effective Management of Corrosion Coincident With Seam Welds

Abstract This paper summarizes an 18-month-long research project funded by the Pipeline Research Council International (PRCI) with the primary objective to clarify what analysis methodologies are appropriate to assess corrosion coincident with a pipeline longitudinal seam weld and to support the development of recommended guidelines to effectively manage these types of features. A critical factor in determining the remaining strength of a corrosion feature intersecting a longitudinal seam weld (LSW) is whether the corrosion is preferential to the weld (often referred to as selective seam weld corrosion or SSWC) or coincident with weld yet no preferential attack of the bondline is occurring. SSWC is a form of corrosion that most often occurs in the bondline of electric resistance welded (ERW) and electric flash welded (EFW) pipe and typically has the appearance of a V-shaped groove. Past research supports that if no preferential attack of the LSW bondline is occurring and the weld has adequate ductility, the presence of the LSW does not reduce the remaining strength of the feature when compared to features not intersecting the LSW, and that industry accepted corrosion assessment models are suitable. The overall project scope included the execution of destructive testing of corrosion features intersecting an LSW, material property testing of LSWs produced by multiple manufacturing methods, detailed engineering analysis, and a literature review of all past relevant research. This document summarizes each of the above items, as well as the identification of guidelines and criteria to effectively manage corrosion intersecting an LSW. In addition to the learnings from the project tasks discussed herein, the final guidelines for effective management of corrosion coincident with LSWs consider the susceptibility of the affected pipeline to SSWC and the capability of different inspection technologies (ILI and in-ditch) to effectively identify and characterize potential SSWC. These guidelines will also serve as the basis for recommendations to revise the language of CFR 195.452 and API RP 1176. The work presented in this paper is part of the PRCI project EC-02-13 “Response to Corrosion Interacting with the Longitudinal Seam in Liquid Pipelines.” This work is being executed in parallel with sibling projects EC-02-12 “Evaluation of Selective Seam Weld Corrosion Susceptibility.” NDE-4-13 “Selective Seam Weld Corrosion Detection with In-line Inspection Technologies.” IM-3-03 “Comprehensive Review and Assessment Guidelines for SSWC,” IM-1-08 “Pragmatic Application of MegaRule RIN 1 - 192.712 Toughness Values,” and NDE-2-15 “SSWC Identification, Sizing, and Measuring Grooving Ratio in the Ditch.”