Lessons learned from a hydrogen explosion in a process unit

Polysar Limited operates a large petrochemical complex in Sarnia, Canada with several plants that produce monomers and synthetic rubber. On Good Friday, April 20th, 1984, there was a hydrogen explosion and fire in the Litol benzene unit of Polysar's Styrene I plant. Two men were killed and two more were injured. Injury and loss of life would likely have been greater had the explosion not happened on a plant holiday. The explosion occurred when the unit was being restarted following a scheduled shutdown for maintenance. The explosion followed the release of about 30 kilograms of hydrogen gas into a compressor shed from a burst flange operating at 4800 kPa (700 psig). The findings of the investigation into the explosion and the actions taken to prevent a re-occurrence are discussed.