200228 Enclosed Space Incident

Enclosed Space Incident
Report No. 200228

A hazardous incident occurred on board a tanker while crew members were engaged in rinsing and mopping up in a slop tank and discharging oily water slops with a pump into oil drums on deck. The slop tank had been water washed, purged with inert gas and gas freed with air. Although the report stated that safety measures were observed, these measures were not defined other than the fact that a reading of 20.9% O2 by volume and 0% LEL had been obtained prior to entry.

The report stated that the Chief Officer entered the slop tank first and found a breathable atmosphere, the methodology used to reach this conclusion was not defined. Shortly afterwards two crewmembers entered the slop tank and commenced work as described. Within a short space of time the atmosphere became unsafe and again, the methodology used to reach this conclusion was not defined. Fortunately on this occasion, the tank was evacuated without injury or loss of life. The report concluded by stating that perhaps the removal of the oil caused the problem and that on the next occasion such an operation was carried out, it would be necessary to continuously ventilate the tank with air.

Lessons Learned

From the information provided, the incident would appear to have been caused by crewmembers failing to follow Company procedures and industry guidelines effectively in relation to the implementation of 'Work Permit' and 'Enclosed Space Entry Permit' systems. The ineffective use of these systems ultimately led to inadequate enclosed space entry arrangements and work procedures relating to the removal of sludge.

Atmospheric hazards kill more people than all other confined space hazards combined, therefore it is imperative that Company procedures and industry guidelines are strictly adhered to. The principal dangers associated with enclosed spaces are oxygen deficiency, flammable, and toxic gases. It is essential that pre entry tests are carried out to find out what hazard exists and that steps are taken to remove any hazard found. While crewmembers are within the space, frequent atmosphere monitoring and continuous ventilation is necessary to ensure that no new hazard is generated. Remember, ventilation may just be keeping pace with the generation of hazardous gases and therefore must be continued throughout the operation.