A faulty O-ring seal on a composite boiler burner unit led to a fire aboard the bulk carrier Lem Verbena in January 2025, according to a National Transportation Safety Board (NTSB) report released on March 11.
The incident occurred while the 655.8-foot-long (199.9-metre) vessel was docked at the Alabama State Docks on the Mobile River.
The federal agency estimated that the blaze caused $5.5 million in damage to the steel-hulled ship. No injuries or environmental pollution were reported following the emergency, which involved nineteen crewmembers.
The second engineer observed ignited fuel dropping down from the upper deck at 23:22 on January 4, 2025. The crew responded by activating the vessel's carbon dioxide fixed fire extinguishing system and sealing the engine room.
The master notified the Mobile Fire-Rescue Department, whose members arrived on board at 23:50. Shoreside firefighters entered the space after allowing for a soak time and confirmed the fire was extinguished at 00:37 on January 5.
Investigators found that an O-ring within the burner unit's oil fittings block had become, "pinched between the two modules". This misalignment prevented the seal from seating properly and allowed pressurized fuel to escape.
The NTSB stated that the leaked fuel likely atomized and ignited on a nearby hot surface. US Coast Guard investigators also discovered a partially stripped bolt that prevented the burner from being tightly secured to the boiler.
A software error on the system's SD card further contributed to the failure by keeping the fuel pump active between cycles. Lemissoler Shipmanagement concluded the fire resulted from an "exploding leakage" at the weakened seal.
The NTSB noted that all scheduled maintenance tasks for the boiler had been completed prior to the accident.
