The Delaware Fire Marshall says the explosion and fire was caused by a corroded pipe.
The massive fire and explosion at Sunoco’s refinery in Claymont was an accident. That’s the official conclusion of Delaware State Fire Marshal Grover Ingle following a lengthy investigation into the cause of the blast.
The explosion happened around 10:30 PM on May 17. The initial explosion rocked homes nearby and the flames could be seen for miles around. The cause? Corrosion on the outside of a 10 inch pipe that carried ethylene unit feed gas. That corrosion allowed the gas to leak out, causing nearly instant combustion when it came in contact with a scorching hot unit nearby. The corrosion was on the underside of the pipe, where it came in contact with a metal sleeve. That u-shaped sleeve which was on top of an 18 foot tall concrete support, hid the corrosion from view.
Sunoco officials say although the pipe that leaked was more than 40 years old, it had undergone regular inspections. Its last inspection was in March of this year. Sunoco’s Thomas Golembeski says, “That wall thickness test had been performed at representative places along the pipe, and no issues at all were found, but those wall thickness testings did not occur at the spot of the corrosion.” A visual inspection of the pipe was done in 2005. “One of the lessons learned is clearly that our inspection practices can be improved,” says Golembeski.
Golembeski says Sunoco is in the process of inspecting the rest of its facilities nationwide for flaws in similar pipes. He says inspectors have found nothing similar at the facility in Claymont, although some similar risks have been found at a Sunoco facility in Toledo, Ohio. Sunoco is sharing the findings of its own investigation into the explosion and fire with other companies that operate refineries and chemical plants in an effort to prevent a similar situation somewhere else.
Despite the massive explosion and extensive fire, no one was injured in the blast.