In December 2024, the U.S. National Transportation Safety Board (NTSB) held an in-person public board meeting to discuss the probable cause of a natural gas-fueled explosion and fire at the R.M. Palmer candy factory in West Reading, Pennsylvania, USA.
The explosion on March 24, 2023, occurred when natural gas transported though a UGI Corp.-owned pipeline leaked into and accumulated in the factory’s basement. The gas ignited, causing an explosion and fire that killed seven Palmer employees, injured 10 people, and destroyed the facility. Another Palmer building, as well as an adjacent apartment complex, were also badly damaged.
In an ongoing probe, NTSB investigators say they found a series of failures involving a corroded steam pipe and a defective natural gas fitting. In addition, they determined that the factory failed to have natural gas emergency procedures in place that could have resulted in an immediate evacuation.
According to the findings, an old Palmer steam pipe cracked due to preexisting corrosion, thereby allowing steam to escape while raising the temperature of UGI’s gas fitting—which also cracked. Gas then migrated underground and made its way into the basement of a second building, where it exploded. The ignition source was unclear.
Two years before the blast, a UGI crew replacing nearby gas lines was alerted to the presence of the steam pipe. However, they failed to notify the utility’s safety managers, who could have assessed the pipe for its impact on the gas fitting that ultimately failed, the NTSB found.
“By not addressing the threat posed by the steam pipe, UGI’s distribution integrity management program was not effective in preventing the accident,” the NTSB writes. Furthermore, the board found a delay in shutting off gas after the blast because UGI did not properly mark its valves and a critical valve had been paved over.
Installed in 1982, the service tee that failed was made by DuPont and has a known tendency to crack, NTSB says. The aged plastic piping is still in widespread use, but NTSB notes that many utilities may not be aware of the locations where it is most vulnerable to failure from elevated temperatures.
Among a series of recommendations, the NTSB is urging asset owners of buildings served by natural gas to install alarms that can detect leaks.
For more information, visit www.ntsb.gov.