Pipe Corrosion led to Delaware Refinery Explosion

Pipe corrosion that went undetected for years led to an explosion and fire that rocked a Sunoco oil refinery in Claymont in May, authorities said.

Investigators said the corrosion, caused by unseen condensation moisture that had collected between the bottom of a 10-inch pipe and a loose steel sleeve on which it rested, resulted in a gas leak that triggered the May 17 fire and explosion.

No one was injured, but the explosion in the ethylene complex at Sunoco’s Marcus Hook Refinery lit up the night sky along the Delaware River and could be seen and felt miles away. Ethylene is a feed stock used in the production of plastics.

State Fire Marshal Grover Ingle said gas leaking from the pipe spread throughout the ethylene unit, where operating temperatures of some equipment ranged from 500 to 1,000 degrees Fahrenheit.

“That was enough for the escaping gases to ignite,” said Ingle, who declared the fire accidental.

Sunoco spokesman Thomas Golembeski said the state’s finding coincides with the results of Sunoco’s own internal investigation.

The corrosion was limited to the underside of the pipe, where the sleeve obscured it from view, he said, adding that the corrosion occurred over many years and was limited to the space between the sleeve and the pipe.

Golembeski said Sunoco has stepped up pipe inspections throughout the company to identify any similar problems and will develop stronger inspection practices that will exceed the current industry standards it follows.

“We don’t want anything like this to happen again,” said Golembeski, adding that the pipe, which is at least 40 years old, was subject to regular five-year inspections and had undergone a wall-thickness test in March.

“One of the lessons learned is that clearly our inspection practices can be improved,” Golembeski said.

Sunoco’s short-term effort to examine piping systems at its facilities to determine whether similar problems exist elsewhere already has paid off.

“A handful have been found at our Toledo refinery that are being addressed,” he said, adding that those inspections involve “low-risk” systems in Ohio that do not pose an immediate safety threat.

Golembeski said Sunoco will share the results of its investigation with the rest of the petroleum industry through trade associations, including the American Petroleum Institute, the American Chemistry Council, and the National Petrochemical and Refiners Association.

In the meantime, the May incident is still being investigated by the Occupational Safety and Health Administration, which Golembeski said has yet to release its findings.