Bunkering Overflow and BDN Dispute at a Product Terminal
At 01:40 the 18,000 dwt product tanker is loading 420 m³ VLSFO through the port manifold at 180 m³/h. No. 3 port fuel oil tank is receiving; No. 4 port tank is isolated. The tank gauging system for No. 3 has shown a fixed 91% for the last 20 minutes, and the deck watch reports a thin film of oil around the No. 3 vent head and a strong diesel smell. The high-level alarm has not sounded. The bunker barge's manifold pressure is steady at 0.45 MPa. The second engineer is supervising, an oiler is at the manifold, and the chief engineer has just arrived on deck. The vessel is alongside a terminal in a special area; wind is light onshore. The barge master is asking to continue at reduced rate to finish the parcel.
1. What immediate actions would you take and in what order? Explain why you would not simply reduce the pumping rate and finish the parcel.
Read the worked answer
Stop the transfer first. Use the agreed signal or radio to tell the barge to stop pumping, then close the vessel manifold valve and the No. 3 tank valve. Do not rely on the barge alone, and do not continue at reduced rate while oil is already on deck.
Raise the alarm and muster the spill team under the SOPEP. Plug scuppers, contain the oil with absorbent or booms and prevent it from reaching the water. Do not wash the deck with water, because that spreads the spill.
Take an independent sounding of No. 3 tank and check the vent and adjacent tanks. Confirm whether the gauge is stuck and whether the high-level alarm is functional.
Notify the terminal, port authority, company and DPA as required, and make the initial report. Keep the barge informed and preserve samples and records.
Continuing at reduced rate is unsafe because the indicated level is unreliable, the high-level alarm has not operated and oil has already escaped. The remaining parcel is not worth a larger pollution incident or a false BDN.
2. How would you record the event and handle the bunker delivery note and samples?
Read the worked answer
Make an entry in the Oil Record Book covering the bunkering operation, the overflow or spill, the time, location, estimated quantity and the action taken. Entries must be factual and made as soon as practicable; do not backdate or alter them to match the barge figures.
Do not sign a clean BDN. Sign with a written protest stating that the tank gauge was unreliable, the high-level alarm did not sound, oil was found at the vent and the delivered quantity is disputed. Record the barge name, tank numbers, times, flow rate and manifold pressure.
Retain the vessel's samples and ensure the barge samples are taken and sealed in the normal way. Record sample numbers and witnesses.
If the spill is reportable under the applicable regulations, notify the authorities within the required time and keep copies of all reports. The BDN and Oil Record Book must tell the same story as the incident report.
3. What root causes and procedural changes would you investigate after cleanup?
Read the worked answer
Investigate the stuck gauge, the high-level alarm circuit and the valve lineup. Check whether the alarm was tested before bunkering, whether the tank was being sounded independently, and whether the manifold watch and tank watch had clear communication.
Review the pre-bunkering checklist and loading plan: tank capacities, alarm set points, emergency stop signal, valve markings and the maximum filling rate for the final 20% of each tank. Check supervision and rest hours, because the event occurred at night with a senior engineer newly arrived on deck.
Corrective actions should include testing high-level alarms before every bunkering, using independent sounding or a second gauge during the final stage, marking and locking isolation valves, holding a pre-bunkering meeting with the barge, and drilling the emergency stop and spill response.
Record the findings in the safety management system, assign actions and follow up. The goal is to fix the gauge and the procedure, not only to clean the deck.