Tosco Refinery fire
Flawed Management Supervision
Summary
Data:
Date: February 23, 1999,
Location: Avon refinery in Martinez, California,
What happened: Four workers were
killed in a fiery accident. The men were in the process of replacing corroded
pipes at one of the refinery’s oil fractionators
Causes: The project was classified as low-risk
routine maintenance, no special precautions were in place. The fractionator
continued to operate, with large volumes of flammable vapor and liquid flowing
inside the tower and its attached piping
What
Happened ?
Earlier that morning, under the direction of a Tosco maintenance
supervisor, workers had removed a section of corroded naphtha piping 112 feet
up the tower, near where the piping joined the fractionator. But things had not
been going as planned. When a second cut was made 26 feet below the first,
petroleum naphtha – a volatile hydrocarbon mixture that ignites spontaneously
at 232°C – began to ooze out and workers had to immediately reseal the pipe.
After breaking for lunch, the workers climbed 40 to 100 feet up scaffolding
alongside the tower. They tried to drain the piping system of naphtha by
opening a pipe flange 36 feet up and directing the leaking fuel into a vacuum
truck using makeshift plastic sheeting and a bucket.
The operation proceeded without apparent problem for 30 minutes, when
suddenly a large volume of naphtha, propelled by vapor pressure from the
operating fractionator, shot out of the open pipe overhead, spraying the
workers. For the five men high on the scaffold, there were few avenues of
escape as the hot surface of the fractionator ignited the naphtha, engulfing
them in flames.
Although emergency teams arrived quickly, no one could approach the victims
for 20 minutes because of the fire. One man died at the scene, three died at
the hospital and another, who had thrown himself off the scaffolding to escape
the flames, survived with critical injuries.
Recurring
naphta leaks
The Chemical Safety Board investigated the accident, Tosco’s second in two
years, to determine root causes. Almost two weeks before the accident, on
February 10, operators had observed a naphtha leak coming off the fractionator,
which they treated as an emergency at the time. Workers located a pinhole leak
in the naphtha piping 112 feet up and closed a series of valves in an effort to
eliminate it. But the leaks kept recurring. In succeeding days, one attempt
after another failed to completely staunch the flow of naphtha. Shut-off valves
malfunctioned repeatedly, and drain valves were found to be clogged beyond use
or repair.
Ultrasound and X-ray tests were ordered, and these revealed that both the
piping and the valves were severely corroded and needed to be replaced.
Although the unit operator argued for shutting down the process before
attempting to replace the deteriorated piping, a maintenance supervisor decided
to do the job while the hot fractionator continued to run. This fateful
decision did not receive any oversight or scrutiny from the facility’s
management.
Process
should have been shut down
Good operating practice calls for draining hazardous materials from lines
and equipment and verifying that the equipment has been isolated before opening
for maintenance. But that could not be done at Tosco so long as the
fractionator was operating. The repeated recurrence of naphtha leaks was a
strong indicator that shutoff valves were corroded and were not functioning
properly. As long as the fractionator was running, naphtha continued to leak
into the piping, and vapor from the fractionator pressurized the escaping fuel.
In the 13 days that elapsed between the first occurrence of the leak and
the fatal accident, Tosco personnel missed numerous opportunities to reassess
the hazards of the pipe replacement work and take measures to ensure the work
would be performed safely. In this case, such safety measures would have
included shutting down the fractionator as the only way to eliminate both the
source of the naphtha and the potential sources of its ignition.
Avon did not have a systematic job planning and authorization process to
ensure that this kind of maintenance work received appropriate scrutiny before
going forward. No formal hazard evaluation was conducted before or during the
maintenance project, and managers and safety specialists were not sufficiently
involved in decision-making and oversight. Instead, individual workers were
given the authority to put a halt to unsafe work.
Corrosion,
management of change of programs
The naphtha piping and valves had been run to the point of breakdown due to
corrosion, leading to a potentially hazardous situation. The valves and piping
had corroded at an excessive rate because an upstream vessel known as the crude
oil desalter was being operated beyond its design lim- its. Tosco had routinely
processed excessive volumes of crude oil with high water content, overtaxing
the desalter.
As a result, water and corrosive materials like ammonium chloride were
carried over into the fractionator, where they began to deteriorate the piping
and valves.
Key
recommendations
The CSB recommended that Tosco conduct periodic safety audits of its
refineries and document all findings in writing. The CSB said audits should
examine the conduct of hazardous non-routine maintenance, the role of
management in overseeing safety, and the corrosion control and management of
change programs. Audit findings and recommendations should be shared with the
workforce and tracked to completion.
The Board recommended that the refinery, implement a program to ensure that
hazardous non-routine maintenance is conducted safely. The refinery should
require a written hazard evaluation by a multidisciplinary team before any
hazardous job is started. The refinery should also require higher levels of
approval for higher hazard jobs, develop a written protocol for making shutdown
decisions, and make sure that managers and safety officials provide adequate
oversight for hazardous work.
The Board also recommended that the refinery improve its management of
change and corrosion control programs to prevent situations where safety is
compromised.
Tosco Final report :
http://www.csb.gov/assets/1/19/Tosco_Final_Report.pdf
