Battelle is continuing work on a comprehensive study of electric resistance weld (ERW) pipe failures. The Longitudinal ERW Seam Failures study will identify actions that could be implemented by pipeline operators to reduce the risk of longitudinal seam failures in ERW pipes.
The Pipeline and Hazardous Material Safety Administration (PHMSA), part of the Department of Transportation (DOT), initiated the study in response to the National Transportation Safety Board (NTSB) Recommendation P-09-1, which identified areas of concern related to ERW pipe. Battelle was contracted to lead the study in 2011, and is working with Kiefner and Associates (KAI) and Det Norske Veritas (DNV) as subcontractors.
ERW pipe is often found in pressure pipes commonly used to carry natural gas. ERW, a technique used since the 1920s, uses an electric current to bond the seams of steel pipes without the use of welding filler material. Until the 1970s, manufacturers used a low frequency AC current to heat the edges of the seam. However, over time these welds were found to be susceptible to selective seam corrosion, hook cracks and inadequate bonding of the seams. While a more reliable high frequency process is now used for new pipeline construction, thousands of miles of original ERW pipe are still in use today. Reliable methods are urgently needed to evaluate the condition of this existing infrastructure and identify pipelines at risk of failure.
The goal of Phase I of the project was to develop a better understanding of the current state of these issues, including failure rates, conditions that predict failure, and the reliability of current testing equipment. Researchers gathered extensive data on the failure history of vintage ERW seams, including flash-weld (FW) pipe and selective seam-weld corrosion (SSWC), and performed a technical literature review. Researchers also developed experimental studies to better characterize the failure of ERW/FW seams and analyzed the effectiveness of existing in-line inspection (ILI) and hydrotesting technologies for detection of flaws in ERW pipes. Study data was used to quantify the resistance of ERW/FW seams and their response to pressure and develop predictive modeling methods. The final report detailing Phase I activities and results is publically available on the PHMSA website.
Phase II work is still ongoing, and is scheduled to be completed by the end of this year. In Phase II, researchers are working to develop workable hydrotest protocols for ERW/FW seam defects and improve the sensors, interpretive algorithms and tool platforms of ILI and in-the-ditch-methods (ITDM) to improve defect detection. They will also validate computational models used to assess and quantify defect failures and develop a software tool to support integrity management of seam welds. The final reports for Phase II will be available in early 2016.
Battelle has a long history of pipeline safety and integrity work for the oil and gas industry. Battelle is an industry leader in advancing the science of corrosion detection and mitigation, including development of new detection technologies for Microbial Induced Corrosion (MIC) and the Battelle Smart Corrosion Detector Bead. At the Battelle Pipeline Inline Inspection Facility in West Jefferson, OH, researchers evaluate in-line inspection devices (pigs) to find out how accurately they pinpoint pits, cracks, thinning walls and other pipeline flaws. The facility has one of the largest archives of pipes in the world, with pipe diameters ranging from 16” to 42” and various materials characteristics.
Battelle also performs extensive field work including pipeline evaluation, risk analysis and mitigation. In a current project for a commercial customer, Battelle researchers are using operational analysis and computational modeling methods to determine where and how operational failures are likely to occur in a cross-country hydrocarbon fluids pipeline. Battelle will use the analysis to make recommendations for both operational changes and physical changes to the pipeline itself in order to reduce the risk of future operational problems or pipeline failures.