Following its preliminary inquiry into the recent accident at the Goodyear rubber manufacturing facility in southeast Houston, the U.S. Chemical Safety Board (CSB) announced it will proceed with an investigation of the causes of the event. During the accident, one employee was killed and approximately seven others were injured, including several contract workers who were exposed to hazardous anhydrous ammonia.
The accident occurred on June 11 during a maintenance operation on a heat
exchanger that used pressurized, liquid ammonia to cool chemicals that are
later processed to make synthetic rubber. The rubber-making chemicals were
pumped through steel tubes inside the heat exchanger, while ammonia flowed
through a cylindrical steel shell that surrounded the tubes.
The day prior to the accident, the process was shut down for cleaning. During
the shutdown, an isolation valve was closed between the heat exchanger and a
pressure-relief device designed to protect the heat exchanger from possible
On the morning of the accident, an operator used steam to clean out process
piping; the steam also flowed through the heat exchanger tubes. The steam
heated the liquid ammonia remaining in the exchanger shell, which caused the
pressure to build. With the path to the pressure-relief device blocked, the
heat exchanger ruptured catastrophically.
An operations supervisor who was not involved in the maintenance work but was
working in the area was killed by the explosion. Her body, which was covered
with explosion debris, was not discovered until several hours after the
emergency had been declared over.
Since the accident, CSB investigators have completed two week-long visits to
the plant conducting interviews and gathering other evidence.
"This tragic accident is but the latest example of the destruction that
can result from a lack of effective pressure relief systems and
practices," said CSB Chairman John Bresland, who personally visited the
accident site on June 12. "Companies should be vigilant to ensure that
pressure-relief systems are adequate and are properly maintained and operated
to continuously protect equipment from overpressure."
Chairman Bresland said the CSB investigation would likely focus on the
company's practices for managing, inspecting, and maintaining relief systems;
training operators; and accounting for workers during emergencies. A case study
report is expected at the end of 2008.