Findings of a metallurgical investigation into the cause of the Mayflower oil spill point to manufacturing defects, the same defects that the pipeline industry has known exist in pipelines, like Exxon’s Pegasus, since as early as 1989.
Multiple reports, including one of more than 200 pages of highly technical information released at the close of a metallurgical study of the failed pipeline Thursday, show pipelines similarly manufactured, and in the same era as the ruptured line in Mayflower, are inferior and susceptible to failure.
The awaited metallurgical study findings released Thursday and comments ExxonMobil made in a meeting this week with Congressman Tim Griffin raise critical questions.
Griffin said Thursday Exxon officials admitted a corrosion test from 2010 and a test performed this year to detect cracking within the pipeline did not show any indication of a manufacturing flaw.
Exxon’s admission pulls into question Exxon’s current inspection tests’ relevancy if tests failed in February to detect defects that would lead to a more than 5,000 barrel crude oil spill in March.
The Log Cabin Democrat posed the question to Exxon spokesman Aaron Stryk Thursday, but that and other questions were not answered by the time this report was published.
Stryk was also asked if Exxon was aware that pipes like the Pegasus, which was manufactured using electric resistance welding, or ERW, had been widely documented as problematic and prone to hook cracks that would lead to failures along the ERW seam.
When Exxon received the recently released report from Hurst Metallurgical Research Laboratory in Texas earlier this month, the company released brief findings and said it was up to the other report’s recipient, the Pipeline and Hazardous Materials Safety Administration, to release the report.
Exxon said manufacturing defects, “namely hook cracks near the ERW seam,” were to blame for the spill that released an estimated 200,000 gallons of the toxic substance into Northwoods subdivision, prompting the evacuation of more than 20 homes. The oil flowed downhill through the neighborhood, into a creek, under the Interstate and in drainage ditches to a cove of Lake Conway. Officials say they stopped the oil before it reached the lake.
PHMSA declined until Thursday to make the metallurgical report and spill findings public, citing an ongoing investigation.
Much has been said within the pipeline industry and regulatory agencies about the ERW pipeline and the resulting hook crack phenomenon.
Trade publication “Oil and Gas Journal” author Dr. John F. Kiefner, founder of Kiefner and Associates pipeline consulting firm, of which Exxon is a client, points to pressure management as a solution for the widely “problematic ERW pipe.”
Representatives at Kiefner’s firm would not comment on Kiefner’s research and published pieces and said he had since retired, but recommended the firm’s information as reference.
Kiefner wrote in a 1992 report published in the journal that raising the pressure level in a defective segment of pipe can lead to failure, and flaws in ERW pipelines may grow while the pipe is in service, due to large pressure fluctuations.
PHMSA records show Exxon reversed the pipeline’s flow in 2006 when product volume increased and the pipe began carrying the heavy crude, also called diluted bitumen, from Illinois to Texas.
“A change in the direction of flow can affect the hydraulic and stress demands on the pipeline,” PHMSA’s corrective order issued to Exxon after the March 29 spill states.
Exxon has told the Log Cabin and others in earlier interviews and issued statements that the pipeline’s age, about 65 years, should not indicate its integrity, but pipeline manufactured in the 1940s using the ERW technique is inferior, Kiefner wrote in the 1992 report.
A 1998 assessment of ERW pipelines conducted by the National Institute of Standards and Technology, under the U.S. Department of Commerce, compiled after the Dec. 24, 1988, failure of an ERW pipeline in Maries County, Missouri, also states the pipe manufactured in the 1940s using the ERW technique, as portions of the Pegasus line were, is “inherently susceptible to seam failures.”
The report states special safety standards are only warranted in ERW pipes at “critical risk locations,” due to the small number of failures at the time the report was compiled.
For critical risk locations, defined as a location where risk to public safety, property and environment is large, it is recommended that periodic hydrostatic testing be conducted to eliminate large flaws.
Exxon has performed hydrostatic testing, but the company told Griffin the results did not tip them off about the spill.
“Consideration should also be given to the replacement of the older pipe in certain critical risk locations, since a cost analysis might indicate this to be a better alternative,” the ERW pipeline assessment report states.
PHMSA has classified the Mayflower rupture site as a “high consequence area,” directly affecting a high population area under PHMSA’s integrity management regulations.
The NIST investigation into ERW pipelines goes on to say that while the recommended actions, such as hydrostatic testing, can be expected to significantly reduce the incidence of failure, they are unlikely to completely eliminate failure.
Replacing in-service ERW pipeline or retiring a line is undesirable, Kiefner wrote in the “Oil & Gas Journal,” despite “abundant evidence” that the pipeline is inferior, and reliance is placed on modern methods of testing, the same ones Exxon had told Griffin did not reveal manufacturing defects.
Exxon’s Pegasus pipeline is 850 miles in length.
Jim Hall, former chairman of the National Transportation Safety Board and leader of Washington D.C.-based consulting firm Hall & Associates, said Thursday the Pegasus line’s record “speaks for itself.”
“If you’re interested in safety, it needs to be replaced,” he said. “Or at least there should be safe rules for the operation.”