Session: 05-02-03 Weld NDE and ECA

Paper Number: 86737

86737 - Development of Alternative Weld Flaw Acceptance Criteria for Pipeline Construction Using a Hybrid of Semi-Automatic Waveform Controlled Gmaw and Mechanized FCAW-G Welding Processes 

Pipelines are widely used in the oil and gas industry for transporting crude oil and natural gas from the field to refineries. It has been a general practice to use alternative weld flaw acceptance criteria to assess the acceptability of mechanized girth welds using an engineering critical assessment (ECA) approach. The ECA concept of defining weld flaw acceptance criteria has been accepted as a fitness for service (FFS) assessment based on fracture mechanics, which requires robust welding procedures. Effective planning of the welding procedure specification (WPS) qualification and mechanical testing of the weld and heat-affected zone (HAZ) and weld inspection are the key factors contributing to robust welding procedures and an effective ECA.

Mechanized gas metal arc welding (GMAW) processes are commonly used in pipeline girth weld welding because of their high quality and productivity. With the technical advancements of non-destructive testing (NDT) techniques, the use of automated ultrasonic testing (AUT) with supplemental time of flight diffraction (TOFD) has further enhanced the accuracy and productivity in weld inspection, weld flaw sizing, and probability of detection. Alternative acceptance criteria to assess the acceptability of mechanized girth welds using an ECA significantly reduce the construction cost by minimizing unnecessary weld repairs. Mechanized girth weld acceptance criteria have been progressively transitioned from using workmanship standards into FFS-based ECAs.

The semi-automatic waveform controlled GMAW, and mechanized flux cored arc welding (FCAW) processes are also commonly used in pipeline construction, especially for tie-in welds. However, ECA based weld flaw acceptance criteria have not been applied to welds using the above welding process combinations. This paper focuses on the development of the alternative weld flaw acceptance criteria for mainline girth weld construction using a hybrid of semi-automatic waveform controlled GMAW and mechanized FCAW-G processes. It explains the integration of the robust WPS qualification, mechanical testing, ECA methodology and AUT procedures. The girth weld acceptance criteria were developed based on CSA Z662-19 Annex K using Option 2 methodology.

Presenting Author: Junfang Lu Enbridge Inc.

Presenting Author Biography: Junfang Lu is a Welding Specialist at Enbridge Inc. She has more than 16 years of working experience and has been with Enbridge for 13 years supporting welding activities including construction and maintenance of pipeline and facilities. She has authored more than a dozen of technical papers in Journals and Conference Proceedings on materials and welding. She was the recipient of the Best Student Paper at IPC 2008. She was also the recipient of 2013 Charles Hatchett Award in U.K. for her excellent work on steel microstructure characterization. She holds bachelor’s degree in welding engineering, MSc and PhD degree in Materials Engineering from the University of Alberta.