The U.S. Chemical Safety and Hazard Investigation Board has recommended that BP revise the maintenance program at its Texas City refinery to include verification of all alloy steel piping components. The board said maintenance contractor JV Industrial Companies inadvertently switched an alloy steel elbow resistant to the effects of high-temperature hydrogen with a non-resistant carbon steel elbow. The elbow failed July 28 and released hydrogen gas, which ignited and burned for about two hours. The investigation found that BP had not informed the contractor that the two parts were not interchangeable.