During a Port State Control visit to the ship, it was noted the security system of the incinerator door was disconnected.
Causal factors: Failure to follow planned repair/ maintenance instructions on defective equipment. Inadequate guidelines listed in manuals.
Preventative action: All waste oil incinerator alarms and trip devices were tested as per the monthly checklist and all were in operational condition, without remarks. The main cause of the problem was two small securing bolts, which keep an interlock plate connected to the door. They were not found during the investigation and probably fell down into the incinerator furnace. This in turn was caused by a wrong size or a bad thread condition that allowed them to unscrew due to vibration or heat effect. The repair was put in place immediately and additionally LOCTITE glue used for better securing of these small bolts. The officer in charge and the incinerator operator were instructed to check all safety devices on the incinerator every time before operation
A useful reminder on the importance of safety checks before use of an incinerator.