CLEANUP WORK: A file photo shows workers in Mayflower in April after Pegasus pipeline break.

  • KUAR/Michael Hibblen
  • CLEANUP WORK: A file photo shows workers in Mayflower in April after Pegasus pipeline break.

KUAR’s Michael Hibblen reports that a federal regulatory agency has received from ExxonMobil a metallurgical report that was due today on the Pegasus pipeline that ruptured and spewed tar sands on a Mayflower neighborhood. But the agency is not releasing the findings and what they might reveal about the cause of the rupture as its investigation continues.


UPDATE: Exxon has allowed (AP), however that “manufacturing defects” contributed to the rupture.

Exxon says no corrosion. Tar sands are cool in other words. They haven’t yet said how many hundreds of miles of this line might have manufacturing defects. Here’s the full statement:


ExxonMobil Pipeline Company (EMPCo) and the Pipeline and Hazardous Materials Safety Administration (PHMSA) have received the results of an independent assessment conducted by Hurst Metallurgical Research Laboratory, Inc. on the Pegasus Pipeline segment that failed on March 29, 2013. We are currently in the process of reviewing and analyzing the data.

Based on the metallurgical analysis, the independent laboratory concluded that the root cause of the failure can be attributed to original manufacturing defects — namely hook cracks near the seam.

Additional contributing factors include atypical pipe properties, such as extremely low impact toughness and elongation properties across the ERW seam.

There are no findings that indicate internal or external corrosion contributed to the failure.

While we now know the root cause of the failure, we are still conducting supplemental testing, which will help us understand all factors associated with the pipe failure and allow for the verification of the integrity of the Pegasus Pipeline. These tests will help us determine the mitigation steps we need to take to ensure a similar incident does not occur again.