Accident at rubber plant occurred during maintenance
01 October 2008
The US Chemical Safety Board (CSB) is investigating the causes of a recent accident at the Goodyear rubber manufacturing facility in southeast Houston, in which one employee was killed and approximately
seven others were injured, including several contract workers who were exposed to hazardous anhydrous ammonia.
The accident occurred last June during a maintenance operation on a heat exchanger, which used pressurised, 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 pressurerelief device, designed to protect the heat
exchanger from possible over-pressures. 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.
An operations supervisor, who was not involved in the maintenance work but was working in the area, was killed by the explosion that followed the vessel rupture.
“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 pressurerelief systems are adequate and are properly maintained and operated to continuously protect equipment from over-pressure.”
Bresland suggested the investigation would likely focus on the company's practices for managing, inspecting, and maintaining relief systems; training operators; and accounting for workers during emergencies.
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