The UK P&I Club released guidance to ensure safe bunkering operations. The Club said that bunkering operations are routine and critical, high risk operations which require to be carefully planned and performed.
Causes of bunker spills
Although the most of the bunker transfers are carried out without incident, very occasionally, things can and do go wrong. The UK Club notes that only a minority of cases do bunker spills occur because of failure of the hoses or pipelines, while the majority of spills result from a tank overflowing.
But these are not the only causes. Common causes of bunker spills can be summarised as follows:
- Improper set up of pipeline system valves: Potentially causing either overpressure, or flow of bunkers to an unintended location;
- Insufficient monitoring of tank levels during bunkering: All tanks, not only those nominated to receive the fuel;
- Excessive transfer rate or pressure: Risk of exceeding the design pressure or capacity of the system; also increases operational stress on the crew.
- Air lock: Depending on internal tank structure and the arrangement of ventilation pipework (exacerbated by excessive trim or list), an excessive pumping rate can cause pockets of air to become trapped in the tank;
- Malfunction of valves: Potentially related to lack of valve testing or maintenance;
- Loss of containment from transfer pipelines and hoses: This may be because of poor maintenance/insufficient pressuretesting, over-pressurisation, or failure to properly close/blank off unused manifold connections.
- Human element: Complacency during bunkering operations, high work-load, fatigue, unfamiliarity and poor communication, are all playing a key role.
Safe bunkering operations
A number of safe bunkering measures are required for each bunkering operation. These can be divided into four stages and checks:
- Pre-arrival;
- Prior to bunkering;
- During bunkering;
- On Completion.
Pre-arrival
The crew designated to perform bunkering duties should not be distracted from their task. Key members of staff should be appraised of their forthcoming duties in good time and should be properly rested and rotated as required for the duration of the operation.
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What is more, the Bunker Plan should be completed, confirming the capacity of the vessel’s tanks allows adequate free volume, while a visual check of pipelines, including any internal or external overflow arrangements should also be carried out.
In addition, high-level and overflow alarms should be tested by physical activation if possible and readings of remote level gauges should be verified by manual ullages or soundings.
Finally, the bunker checklist must be diligently completed at appropriate times.
Prior to bunkering
SOPEP equipment should be deployed before starting operations:
- First response equipment should be available adjacent to the manifold. This should include a suitable portable pump and emergency containment;
- Check save-alls around the bunker manifolds and fuel oil tank vents are empty and are fitted with drain plugs;
- Check there are no non-bunkering related leaks which could fill shared containment arrangements;
- Deck scuppers and freeing ports should be plugged with suitable dedicated devices. Consideration should be made for controlled drainage in the event of rainfall.
During bunkering
On commencement, the manifold pressure should be kept to a minimum until it is clear that the intended tanks are filling, and there is no delivery to unintended tanks, overflow or leakage. When satisfied, the pumping rate should be increased until the agreed pressure/flow rate is reached; this may not necessarily be the maximum.
Regular communication checks with the supplier should also be maintained, along with a continual manifold watch throughout the bunkering operation.
Furthermore, when topping-off tank levels or reducing capacity by closing full tanks off, the supplier should be warned, and an appropriate reduction in flow rate considered.
On Completion
The manifold valve should be closed. Following disconnection, the hose blank and the bunker manifold blank should be securely fitted without delay. The hose should not be lifted away from the manifold save-all until this has been done. The vessel’s fuel system valves should be re-aligned for normal operation. Consideration should be made to leave scupper plugs in place until departure from the port, but all SOPEP equipment should otherwise be secured and restowed appropriately.
The Master should confirm to the agent that bunkering operations are completed without incident.
See more details in the PDF below
Yes insufficient pressure testing is often a reason..