As part of its Good Catch series, the American P&I Club draws lessons learned from an incident in which a fire occurred due to cracked refractory bricks caused by thermal shock from adding cold water during incinerator operation.
The Third Assistant Engineer on a general cargo vessel was operating the vessel’s incinerator. He had received prior on-the-job training for the incinerator and had operated it several times without issues. He also ensured the operation was properly logged.
On that day, the incinerator was burning sludge oil in a continuous feed. After approximately 30 minutes of operation, he noticed smoke filling the incinerator room. The fire detection system alarmed immediately thereafter. The Third Assistant Engineer pressed the emergency stop on the incinerator and evacuated the space. The crew mustered, and the Chief Engineer and Master approved the use of the water mist extinguishing system in the space. It worked effectively, and the fire was quickly extinguished.
An investigation revealed that the refractory brick was severely cracked. The incinerator manufacturer’s representative attributed the cracking to temperature shock, typically caused by cold water contacting hot refractory brick. The crew admitted to occasionally adding water to the sludge tank while the incinerator was operating, unaware of the potential damage to the refractory bricks. The water was added to make the sludge flow more easily and prevent clogs that could shut down the incinerator. However, when added while the incinerator is running, cold water can create a temperature shock, causing the refractory brick to crack.
The cracks allowed excessive heat to escape from the incinerator, causing oil-soaked insulation on the nearby waste oil tank to smolder and ignite.
Potential damage
Had the Third Assistant Engineer not been attentive, the fire could have burned longer, potentially damaging the incinerator beyond repair. The fire might also have spread to adjacent compartments. Repair costs could have exceeded $200K.
Lessons learned
- Does your training emphasize safe incinerator operation and include precautions to prevent thermal shock to the refractory brick?
- Is your crew reminded not to add water to the sludge tank when burning sludge to avoid thermal shock?
- Is the refractory brick regularly inspected and repaired as needed to ensure it is in good condition?
- Are regular inspections and tests of the incinerator automation and safety devices conducted?
