"Although this latest explosion and fire fortunately caused no injuries, such accidents are not an acceptable part of normal operations," CSB Chairman Carolyn Merritt said. "The accident occurred at an entirely different part of the Texas City facility, but we are interested in knowing whether the two accidents share any common root causes such as lack of an effective mechanical integrity program. Such a program would make sure the equipment is safe and serviceable."
The July 28 explosion occurred in the refinery's resid hydrotreating unit (RHU), which processes "resid," a heavy crude oil, into refined products such as gasoline. The blast caused no injuries but prompted Texas City officials to issue a shelter-in-place order after the 6 p.m. blast due to concerns that winds might carry smoke and fumes into the city.
The RHU is on the opposite end of the Texas City refinery from the isomerization unit, where the deadly March 23 blast occurred. BP spokesperson Howard Miller told Occupational Hazards.com that company officials believe the two incidents were not connected.
"The two units are about a mile away from each other," Miller said. "There's no production link between the RHU and the isom unit."
'Large Jet Fire'
The July 28 explosion occurred when an 8-inch pipe connected to a heat exchanger failed at the flange a pipe fitting that connects equipment such as pipes and valves according to CSB investigator Giby Joseph.
"Recycled gas, primarily hydrogen, was suddenly released when the pipe broke away," Joseph said. " The hydrogen, under high pressure and temperature, was ignited, sending a large jet fire shooting an estimated 75 feet westward from the flange. Damage was localized along that fire path."
Initial information indicates the hydrogen was pressurized at approximately 3,000 pounds per square inch at a temperature of over 500 degrees Fahrenheit, according to Joseph. Heat from the fire deformed piping and bent structural beams, he noted.
The incident occurred during routine operations, and not during maintenance or a startup, according to CSB.
Witnesses report having received no warning indications before the pipe failure and explosion, the agency says.
CSB says its investigators were told that 13 workers were in the area, including several contractors. BP has provided CSB investigators with handwritten eyewitness statements from employees, who will be interviewed this week by CSB.
At press time, CSB investigators Joseph and Francisco Altamirano who also are part of the CSB team currently investigating the March 23 explosions and fire had made two visits to the site where the accident occurred. After an initial assessment is made of the July 28 accident, CSB will determine whether it would form part of the ongoing investigation.
Lead investigator Donald Holmstrom, in charge of the March 23 explosion investigation, was expected to arrive in Texas City on Aug. 1.