CSB Issues Safety Bulletin on BP Texas City Fire
October 24, 2006 // Published as a news service by IHS
The fire occurred four months after the explosion in the refinery's isomerization (ISOM) unit that killed 15 workers and injured 180.
The July 28 fire caused $30M in property damage. Weeks later, this accident was also cited in the CSB urgent recommendation for BP to examine the safety culture at all its North American refineries.
The fire occurred on the evening of July 28 when a piping elbow failed catastrophically and without warning, releasing highly flammable hydrogen gas at high temperature and pressure that immediately ignited. A huge fireball erupted and a fire burned for approximately two hours.
The CSB safety bulletin notes that the piping system for an RHU heat exchanger contained three elbows of identical dimensions and appearance. Two elbows were constructed of alloy steel and were resistant to the effects of high-temperature hydrogen, but the third elbow was made of carbon steel, which is not resistant.
In February 2005, five months prior to the fire, the unit was shut down for routine scheduled maintenance. During the maintenance shutdown the contractor inadvertently switched the positions of the carbon steel elbow with one of the alloy steel elbows, placing a carbon steel elbow on the outlet side of the heat exchanger, where it would be exposed continuously to high-temperature hydrogen.
The investigation found that BP had not informed the maintenance contractor that the elbows were not interchangeable.
Lead Investigator John B. Vorderbrueggen said "Merely disassembling and reassembling piping components during maintenance resulted in an unacceptable hazardous system modification. BP should have required positive materials verification of these pipe elbows using an x-ray fluorescence test device. This would have identified the mistake in the reassembly of the identically appearing elbows before the unit was returned to service. The accident would not have occurred."
The fire resulted in a Level 3 community shelter-in-place alert in Texas City. Level 3 is the second highest emergency classification that applies to an incident where the situation is not under control and protective action may be necessary for the surrounding or offsite area.
The CSB issued several formal safety recommendations. The BP Texas City Refinery was urged to revise its maintenance program to include materials testing or verification of all alloy steel piping components and to inform work crews of material handling precautions.
The CSB also recommended that JV Industrial Companies update its piping component installation procedures to require material identification for components removed during maintenance to ensure they are reinstalled in the correct locations.
"There are important safety lessons for oil and chemical companies from this incident," said CSB Chairman Carolyn W. Merritt. "Positive materials verification of the components in piping systems can avoid simple mix-ups that can have devastating consequences."
The bulletin also emphasized what it calls "human factors based design" - that is, designing components so that foreseeable human errors are less likely to occur.
Source: U.S. Chemical Safety Board (CSB).