CSB Safety Video: Preliminary Animation of 2019 Fire and Explosions at PES Refinery in Philadelphia, PA

The U.S. Chemical Safety Board (CSB) has released a preliminary animation detailing the events leading to the June 21, 2019, explosion and fire at the Philadelphia Energy Solutions (PES) Refinery in Philadelphia, PA. 

The CSB also released a Factual Update noting that at approximately 4:00 a.m. a pipe elbow, which had corroded to about half the thickness of a credit card, appeared to have ruptured in the refinery’s alkylation unit, releasing process fluid that included over 5,000 pounds of hydrofluoric acid. The leaking process fluid formed a large ground-hugging vapor cloud. Two minutes later, the cloud ignited, causing a massive fire and explosions.

While the CSB’s investigation is still ongoing, the factual update notes important details of the incident collected through interviewing witnesses, gathering evidence and ultimately, piecing together the events that led to the explosion:

• The piping was susceptible to corrosion from the hydrofluoric acid that was in the process fluid. The elbow that ruptured corroded faster than the rest of the piping in this part of the process. 
• While pipe thickness in this section of the unit was periodically measured to monitor corrosion rates, the thickness of the elbow that failed had not been monitored for corrosion. The piece of piping that failed had a high nickel and copper content. Various industry publications have found that carbon steel with a higher percentage of nickel and copper corrodes at a faster rate than carbon steel with a lower percentage when used in a process with hydrofluoric acid.
• A secondary event at the PES refinery occurred when the V-1 Treater Feed Surge Drum ruptured, which launched a fragment of the vessel weighing 38,000 pounds across the Schuylkill River. Two other large fragments landed within the PES Refinery.

About the CSB

The CSB is an independent, non-regulatory federal agency whose mission is to drive chemical safety change through independent investigations to protect people and the environment. The agency’s board members are appointed by the President and confirmed by the Senate. CSB investigations look into all aspects of chemical incidents, including physical causes such as equipment failure as well as inadequacies in regulations, industry standards, and safety management systems. For more information, visit www.csb.gov.