WASHINGTON Aug 1 A leak in Exxon Mobil Corp's
nearly 70-year-old Pegasus pipeline, which spilled
thousands of barrels of crude oil in a small Arkansas town in
March, appears to have been caused by an original manufacturing
defect, U.S. regulators said on Thursday.
The 95,000-barrel-per-day pipeline, which has been shut
since March after spilling about 5,000 barrels of Canadian crude
in Mayflower, Arkansas, will remain shut until it can be
restarted safely, a spokesman for the U.S. Pipeline and
Hazardous Materials Safety Administration said.
The initial review of the ruptured pipeline, prepared by
Hurst Metallurgical Research Laboratory, found the pipeline
failure "resulted from an original manufacturing defect of the
electronic resistance welded pipe," the spokesman said.
The 185-page review concluded it was "highly probable" some
micro-cracking might have occurred immediately following the
pipe's manufacturing, which likely led to further cracking and
thinning of the pipeline during service, and ultimately causing
The report did not give an opinion as to who was to blame
for the failure.
When asked whether Exxon Mobil was responsible for the
defect, company spokesman Aaron Stryk said the Youngstown Sheet
and Tube Company, from Ohio, was the original maker and was no
longer in business.
In 2009, Exxon completed a three-year project to reverse the
Pegasus line to run north to south and increase its capacity by
50,000 bpd. The company did not increase the diameter of the
line, but raised the pressure of it.
The review said Pegasus was running at above 700 PSIG, or
gauge pressure, at the time of the spill.
The review is one part of PHMSA's ongoing investigation
into the cause of the leak and the regulator, a branch of the
Transportation Department, is working to finalize its
understanding of the cause of the failure, the PHMSA spokesman