The U.S. Chemical Safety and Hazard Investigation Board has released a preliminary report that identifies a failed piping component as the proximate cause of the April 2 explosion at the KMCO chemical manufacturing plant in Crosby, Texas. One worker died in the accident and at least thirty others were injured, including two workers who received second- and third-degree burns. The failed component, known as a “y-strainer,” resulted in a leak of isobutylene, a highly flammable, colorless gas used in the production of products such as aviation fuel, packaging, and plastics. According to CSB, the Crosby plant uses isobutylene in a process to manufacture lubrication additives and other chemicals. The CSB report states that on the morning of the accident an operator was walking by a reactor used to produce sulfurized isobutylene when he heard a loud “pop” followed by a hissing sound. A vapor cloud of isobutylene formed, found an ignition source, and exploded, destroying a building at the plant. Members of the community within a one-mile radius of the plant were advised to shelter in place.  An autopsy determined that the deceased worker was killed by shrapnel from the explosion. CSB did not indicate when it expects to complete its investigation. To read the CSB report, visit the agency's website.