Spectra Energy Corp. officials on Tuesday said a confluence of factors led to the April explosion of its Texas Eastern Transmission LP (Tetco) pipeline in Southwest Pennsylvania, mainly attributing the blast to significant corrosion that has changed the way it will inspect pipes going forward.
The company addressed local, state and federal officials along with residents in Westmoreland County's Salem Township, where the blast occurred. Spectra reportedly said a test in 2012 revealed that the point of failure had lost more than a quarter of its steel to corrosion. A portion of Tetco, known as the Penn-Jersey system, exploded and caught fire almost five months ago, toppling trees, razing one house and damaging others, as well as severely burning one resident (see Shale Daily, April 29).
The 30-inch diameter Line 27, which ruptured in the explosion, was built in 1981. Spectra officials told residents during the public meeting that the last pipeline test in 2012 didn't alarm the company, according to media reports. Vice President Andy Drake, who handles operations and environmental health/safety, said the line was expected to continue corroding at most at a rate of 2-3% per year until the next inspection, which was scheduled for 2019. Instead, he said, it likely corroded at an unprecedented rate of 10-15% per year.
The Pipeline and Hazardous Materials Safety Administration said earlier this year a preliminary investigation showed evidence of corrosion along two of the affected pipe's welds (see Shale Daily, May 4). A failed tape coating on the pipe at the site has also been installed at hundreds of points along the system. That outdated tape coating, Spectra said, contributed to the corrosion because it lost its ability to shield the metal.
As a result, the company will now inspect its pipelines every three years rather than every five or more. In June, the company said it would voluntarily conduct an assessment along the Penn-Jersey system's entire 263-mile stretch between Delmont, PA, and Lambertville, NJ (see Shale Daily, June 28). It has thus far identified 626 anomalies and excavated 400 of them, making repairs. None have matched the weaknesses at the incident site.
The company also said Tuesday the incident could lead to changes throughout the industry and prompt other midstream companies to more frequently inspect the pipes with the kind of tape coatings that were installed between the 1970s and 1990s. Pipelines have been under intense scrutiny since the deadly San Bruno, CA, explosion in 2010 (see Daily GPI, Aug. 19).
In a notice posted last week, Tetco said it would provide another update on the progress of its work plan on Thursday. The company has said the work is on track for full service by Nov. 1 for the winter heating season (see Shale Daily, Aug. 31).