Session: 05-02-03 Weld NDE and ECA

Paper Number: 87297

87297 - Copper Contamination Cracking of Mechanized Onshore Steel Pipeline Girth Welds 

Copper contamination cracking in pipeline girth welds has been experienced in the construction of onshore high strength steel transmission pipelines using mechanized welding. Copper contamination cracking has occurred with mechanized welding using gas metal arc welding short-circuit transfer (GMAW-S) on root pass welds with copper backing, gas metal arc welding pulse-spray transfer (GMAW-P) on fill pass welds, and flux cored gas-shielded arc welding (FCAW-G) on fill pass welds.

Copper is a common alloying element and generally soluble in steel. However, copper contamination cracking, which is a type of liquid metal embrittlement (LME), may occur if copper is melted or abraded onto a steel weld surface and reheated from subsequent weld pass(es), where the copper melts, penetrates, and weakens the steel grain boundaries in the solidified weld metal.

Traditionally, pipeline girth welds were made using manual shielded metal arc welding (SMAW), which is generally not susceptible copper contamination, as copper is usually not present in the weld zone. However, mechanized welding requires the use of copper materials in the weld zone, including the contact tip, gas nozzle, and backing bar when a root pass copper back up clamp is used. Copper contamination cracking is relatively new weld defect type, which is not covered in the welding literature, and not specifically recognized as a production weld defect type by North American pipeline welding standards.

Copper contamination cracking in mechanized girth welds occur in specific weld passes and weld locations, with distinct characteristics which are detectable by common nondestructive evaluation (NDE) methods, including visual testing (VT), radiographic testing (RT), and ultrasonic testing (UT). Copper contamination cracking may be effectively controlled when recognized and actions taken to optimize mechanized welding procedure qualification, minimize contamination of production welds with welding operator training and production controls, and tailor NDE methods and personnel training to improve detection.

Presenting Author: Kenneth Lee DNV

Presenting Author Biography: Mr. Lee is a Principal Engineer in the Welding Technology Group within DNV Energy Systems. With over 30 years of experience in the pipeline and welding industry, Mr. Lee is a recognized expert on pipeline safety and arc welding. Mr. Lee is an experienced pipeline welding engineer and has contributed to international pipeline construction, industry standards, government regulations, and pipeline research.