28 June 2005 22:45 [Source: ICIS news]
HOUSTON (CNI)--A spokesman for BP said Tuesday the latest findings of faulty alarms and instrumentation at the site of the 23 March Texas City, Texas refinery explosion were not surprising.
The Chemical Safety and Hazard Investigation Board (CSB) today released the latest findings of its probe into the blast that killed 15 workers and injured 170 others. CSB investigators said they found evidence that several key pieces of process instrumentation malfunctioned on the day of the explosion. The CSB also said alarms did not sound to warn operators of abnormal conditions in the isomerisation unit.
The CSB said it was continuing to probe the causes of the blast.
BP spokesman Hugh Depland said the CSB findings are “entirely consistent with what we said in our investigation interim findings - this is not a surprise to us.”
Depland said the CSB findings did not conflict with BP’s interim report, which said employees failed to follow procedures that could have prevented the blast during the start-up of the isomerisation unit.
However, Gary Beevers, a district director for the United Steelworkers union, said the findings of faulty alarms and sensor equipment “partially vindicate the operators.”
CSB lead investigator Don Holstrom said one alarm from the isomerisation unit’s raffinate splitter did sound at ?xml:namespace> (9:05GMT) when hydrocarbons reached 72% of the 10-foot mark inside the splitter and soon reached 100% of the 10-foot mark. Under normal conditions, he said, the reading from the level indicator should be 50%.
However, the CSB also found that from () to the time of the explosion nearly six hours later, the level indicator erroneously indicated that the liquid hydrocarbon level in the raffinate splitter tower was below 10 feet and was falling back toward a normal value. “We now know that during this time period, the tower was actually flooding with liquid to a height of 120 feet or more,” Holstrom said.
A geyser-like stream of hydrocarbons erupted and ignited, the CSB said.
Prior to the explosion, another high-level alarm failed to operate, Holstrom said.
Beevers said that according to the USW’s own investigation, unit operators heeded the initial alarm and cut the feed to the raffinate splitter in the early morning hours. However, the feed was resumed when the morning shift took over, he said.
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