* Investigators, regulators question type of pipe Chevron
wants to use
* Chevron says will discuss pipe choice with all raising
questions
* Chevron expects discussions can be concluded quickly
(Adds details, background)
By Erwin Seba
HOUSTON, Nov 19 (Reuters) – Chevron Corp is delaying
replacing fire-damaged pipe on the shut central crude
distillation unit at its refinery in Richmond, California, until
questions raised by investigators and regulators about the
metallurgy of the replacement pipe are resolved, a refinery
official said on Monday.
An Aug. 6 fire at the crude unit began with a leaking pipe
thought to have suffered corrosion from sulfur under the high
temperatures required to refine crude oil. The fire forced a
shutdown of the crude unit and halved motor fuel production at
the 245,000 barrel-per-day refinery in the San Francisco Bay
area.
Chevron had said it would use pipe more resistant to sulfur
corrosion as it repairs the crude unit, but U.S. Chemical Safety
Board Chairman Rafael Moure-Eraso said in a letter on Saturday
that the company’s choice of pipe was not best for preventing
corrosion from sulfur in high-temperature environments.
The City of Richmond, which must approve the plan for
repairing the refinery, has said Chevron must also explain its
choice of replacement piping before it will allow the work to go
forward.
“We will make sure not to proceed until all of these
discussions with all interested parties have occurred,” the
refinery’s senior business manager, Barbara Smith, said in a
presentation to the Bay Area Air Quality Management District
(BAAQMD) Board on Monday.
Smith said she believes the discussions can be performed
quickly. It was unclear how long a delay the discussions might
cause in the repairs.
Richmond Refinery General Manager Nigel Hearne said in a
letter to California pollution regulators earlier this month
that the crude unit, which does all the refining of crude oil
coming into the Richmond plant and provides feedstock for all
other units, was expected to be repaired and restarted by the
first quarter of 2013.
Smith said the major components of the crude unit were not
damaged in the Aug. 6 fire, but the shutdown of the unit has cut
fuel production at the refinery to about 50 percent of capacity.
The pipe that failed, triggering the Aug. 6 fire, was made
of carbon steel and apparently suffered significant thinning due
to corrosion caused by the presence of sulfur at high
temperatures, in a process called sulfidation.
Chevron has said it will make repairs using steel pipe
containing 9 percent chromium to prevent corrosion. However,
Moure-Eraso said in his letter that stainless steel pipe with 18
percent chromium is the best choice to prevent corrosion in
high-temperature sulfur environments.
Further, Moure-Eraso wrote that failure of a pipe with 9
percent chromium played a role in a Washington state refinery
fire in February.
“A serious fire at the BP (Plc ) Cherry Point refinery
in Washington State involved sulfidation corrosion of (9 percent
chromium) steel piping that was in similar service conditions as
the Chevron pipe,” Moure-Eraso wrote.
Smith, however, said 9 percent chromium pipe has a higher
resistance to stress cracking than stainless steel pipe.
BAAQMD directors expressed frustration at being called on to
oversee some aspects of Chevron’s repairs before investigations
by the Chemical Safety Board, the U.S. Environmental Protection
Agency and the California Division of Occupational Safety and
Health are completed.
“It’s very frustrating to hear over and over again that the
investigation is not complete and Chevron’s saying we’re moving
ahead like a train wreck,” said BAAQMD Director Shirlee Zane.
BAAQMD Chief Executive Jack Broadbent said current
regulations allow the Richmond Refinery to make repairs as long
as no changes in process or capacity are made. Chevron has said
there will be no changes in process or capacity of the crude
unit.
(Reporting By Erwin Seba; Editing by John Wallace and Tim
Dobbyn)
