Massive 2019 Philly refinery explosion was caused by a corroded pipe

The federal Chemical Safety Board issued a final report Wednesday that found the 2019 Philadelphia Energy Solutions refinery fire and resulting explosions were caused by a pipe elbow that ruptured due to “extensive” corrosion because to its composition.

The elbow, installed in 1973, corroded faster than other components within the piping circuit because it had a high concentration of nickel and copper that “did not meet the composition limits” that were adopted in later years, according to the report by the Chemical Safety Board (CSB).

“Had the elbow met the composition recommendations,” Wednesday’s report said, “the elbow likely would not have corroded at a significantly faster rate than adjacent piping components and likely would not have failed from excessive thinning.”

The report also found that water pumps an operator tried to turn on after a vapor cloud was released did not work because a control system failed. Three explosions followed.

Those explosions rocked South and Southwest Philadelphia on June 21, 2019, and ended a major chapter in city history. The refinery had been in operation for 150 years, dominating a large chunk of local landscape that became the largest oil refining complex on the East Coast as it processed 335,000 barrels of crude oil each day.

The refinery complex was shuttered and purchased in bankruptcy by Hilco Redevelopment Partners, which is razing the old infrastructure with plans to create what it calls the 1,300 acre Bellwether District — described by the company as a “new home for e-commerce, life sciences, and logistics leaders.”

The refining complex, split into two parts, Girard Point and Point Breeze, had a long history with various owners over the years. Sunoco owned the complex until it was bought by Philadelphia Energy Solutions (PES) in 2012. A cleanup is still underway at the site.

The fire and explosion occurred in a hydrofluoric acid (HF) alkylation unit in the Girard Point refinery. HF is toxic if released in large enough quantities. There was no major release of the gas, however, when the pipe ruptured. The vapor cloud was composed almost 95% by propane and only 2.5% HF, the report states.

The final report confirms the CSB’s preliminary finding in 2019 that the elbow was the cause.

Philadelphia Energy Solutions Refining and Marketing LLC, along with the trust that is liquidating the company’s remaining assets, sued the elbow’s maker, Babcock & Wilcox Co., in 2021 for allegedly mislabeling the pipe. The pipe was installed 46 years before the explosion when the refinery was owned by Gulf Oil.

» READ MORE: Bankrupt Philadelphia Energy Solutions blames ‘mislabeled’ pipe for big blast that led to refinery’s closure

The report also found that PES and Sunoco “never inspected all carbon steel components within the HF alkylation unit,” though it noted that such an inspection was not required.

However, the report states that if either of the two owners had conducted an inspection, it might ”have identified that the elbow was corroding at a faster rate than adjacent piping components, which could have prevented the incident.”

The CSB recommends that changes be made nationally as the result of the explosion.

It says, among other recommendations, that the U.S. Environmental Protection Agency should develop a program that prioritizes inspections of HF alkylation units and that new and existing refineries should be required to perform an analysis to see whether safer alternatives to the use of hydrofluoric acid exist.