Accident: Shell Polymers Furnace Explosion and Fire
Location: Location: Monaca , PA
Accident Occurred On: 06/04/2025 | Final Report Released On: 09/16/2026
Accident Type: Chemical Manufacturing - Fire and Explosion
Investigation Status: The CSB's Final Report was released on September 16, 2026.
On June 4, 2025, at approximately 2:19 p.m. local time, the Shell Polymers Monaca facility experienced an explosion in an ethane cracking furnace. The incident resulted in a fire, a release of ethylene cracked gas and combustion products, and estimated property damage of $95 million.
Review the Shell Polymers Monaca Ethane Cracking Unit process hazard analysis to identify process deviations that are addressed solely with administrative controls. Implement an inherently safer design or an engineered control for any scenario identified that could result in a fatality, serious injury, or substantial property damage.
Based on licensor input and good industry practices, such as ANSI/ISA-61511-2-2018 / IEC 61511-2:2016, Functional Safety – Safety Instrumented Systems for the Process Industry Sector – Part 2: Guidelines for the application of IEC 61511-1:2016 and Part 3: Guidance for the Determination of the Required Safety Integrity Levels, implement and maintain an engineered control to prevent backflow of cracked gas into a furnace during all modes of furnace operation.