West P&I Club has analyzed a pollution incident during a routine bunkering operation at a port where fuel was observed to be overflowing from the air vent from one of the bunker tanks.
A container vessel was conducting a routine bunkering operation at a port. The operation involved the transfer of 117 metric tonnes of very low sulphur fuel oil (VLSFO) from a bunker barge to the vessel’s designated bunker storage tanks. The Chief Engineer and the 2nd Engineer supervised the operation, assisted by engine ratings.
At 17:15, the bunker barge was alongside the vessel. Upon completion of the pre-bunkering procedures, the transfer started at 19:30. Then, at approximately 20:10, fuel was observed overflowing from the air vent from one of the bunker tanks.
In addition, the emergency stop was activated, and the Ship Oil Pollution Emergency Plan (SOPEP) was initiated. Port authorities were notified and it t was estimated that 400 litres of VLSFO spilled into the port’s waters.
Investigation Findings
A detailed investigation into the incident revealed several procedural, operational, and equipment-related shortcomings that contributed to the spill:
- Procedural Deficiencies
- Lack of specified maximum bunkering pumping rate and delivery pressure
- Improper tank soundings
- Operational Shortcomings
- High pumping rate
- Manual sounding issues
- Crew Competency Concerns
- Use of unapproved and outdated drawings and tank sounding tables
- Oil Record Book (ORB) records deficient
- Vent Pipe maintenance. There were no records of air vent pipe head regular maintenance
- Equipment and System Deficiencies
- Lack of high-level alarms
- Lack of pressure monitoring
- Lack of maintenance
- Poor condition of deck scupper plugs
Recommendations
According to West P&I, based on the findings, the following corrective actions were recommended to prevent future incidents:
Procedural Revisions:
Revise bunkering checklists to include:
- Maximum pumping rate and pressure limits.
- More detailed and standardised tank sounding procedures.
- Ensure all checklists and procedural documents are clear and straightforward to enhance crew understanding.
- Ensure that personnel assigned with bunkering operation duties are properly trained and certified and that their roles align with the crew list.
Equipment and System Improvements:
- Install high-level alarms in all bunker storage tanks and ensure they are included in the vessel’s planned maintenance system.
- Upgrade the bunker manifold by adding pressure and temperature gauges.
- Implement a routine inspection and cleaning program for vent pipes to prevent blockages.
- Ensure scupper plugs are inspected and replaced regularly to improve containment in case of overspill.
Operational Enhancements:
- Set up the maximum bunkering rate at 40 MT/hour (as observed in operations prior to the incident).
- Improve emergency response training to ensure quicker activation of the emergency stop procedure.
- Require the use of approved tank sounding tables that account for vessel’s trim and heel to prevent incorrect ullage measurements.
- Require that the vessel’s plans and drawings are revised and updated.
- Conduct an Oil Record Book (ORB) compliance review to ensure proper documentation of fuel transfers and accidental discharges.
