Types of bunkering and bunker fuel oil
Conventionally, bunkering is done in ports but with modern techniques and heavy traffic, bunkering can now be done at sea under normal weather conditions. The most common type of bunkering procedure at sea, is ship to ship (STS) bunkering, where one ship acts as a terminal whilst the other moors. The second type is stern line bunkering, which is the easiest but, at the same time risky way of transferring fuel during bad weather. In terms of fuel, there are two principal types of bunker fuel oil:
- Residual fuel: a mix of refinery residual fuel and distillates blended to meet specification requirements. It is available in different viscosities and high and low Sulphur variants.
- Distillate fuel: a product obtained by condensing the vapours distilled from petroleum crude oil or its products. It comes in two variants, both with high and low Sulphur variants.
- Marine Gas Oil (MGO) – it doesn’t contain any residual component.
- Marine Diesel Oil (MDO) – it may contain a small amount of residual component.
Actions prior to bunkering
The first thing that has to be established before any bunkering procedure, is to identify the person in charge (P.I.C) for both the receiving and the delivering vessel. These people must have full control over the vessel during the transfer.
Prior to bunkering, usually a pre-bunkering meeting with all individuals involved is held, in order to identify risks, discuss plans and agree upon a fixed set of operating procedure. Before the process begins, it must be ensured that all the associated individuals are adequately prepared and have been allocated to their designated jobs. Furthermore, one individual from the team should be held responsible for providing safe access / passage to and from the barge.
The P.I.C, which in most cases is the Chief Engineer, is responsible for the preparation of the bunkering plan. It includes estimated filling grades and respective quantities, designated filling tanks, filling sequences, topping-up, emergency procedures and crew responsibilities.
How to prepare a complete bunkering plan
A typical bunkering plan should include the following:
- Grades to be transferred, their amount and details, such us volumes, loading temperatures etc.
- Stability & Stress condition: Draft forward, draft mid, draft aft and sea condition.
- Emergency procedures: In the event of a spill, the vessel’s emergency procedures must be immediately initiated as per the Emergency Procedure Manual.
- Responsibility for Bunkering Operations: Responsibility for bunkering operations must be identified for all the job functions.
- The sequence of loading, which is agreed with the Chief Officer so that it’s safe to ship’s stability and stress condition.
- Checks prior starting.
- Checks during operation.
- Checks during topping off.
- Tasks after completion.
Crew members assigned to bunkering operations should not have any other duties during operation. It’s critical to emphasize to the crew that if anything seems to be out of order, they have a responsibility to stop or even to shut down the bunkering operation and inform the Officer in charge.
The ship must be ready for any fuel transfer before the actual process. All associated pipes and tanks should be sounded and prepared. Warning signs must be placed and the vessel’s personnel to be briefed. Both the bunker station and its trays must be cleaned, and the deck scupper must be plugged. All necessary overboard valves should be closed, and oil absorbing material should be placed at different strategic / key locations. All tank ventilation and sounding piping system should be checked for being open and closed respectively and all the high-level alarms on each tank are functional.
A detailed hose checking is critical for bunkering operation. Weight, length and condition of the hoses should be checked prior coupling for damage.
The bunkering plan and transfer process should be discussed with the barge crew and appropriate signaling procedure, sampling process and response in time of emergency to be agreed. A proper communication link between the ship’s personnel and the barge must be established. An agreement has to be reached regarding the final quantity to be transferred, measuring unit, flow rate and sampling process.
Preparing bunkering safety checklist
Before the bunkering operation commences, the responsible officers should complete and sign the Bunkering Safety Check-List. The Bunkering Safety Check-List uses statements assigning responsibility and accountability. Once signed, this provides the minimum basis for safe operations as agreed through a mutual exchange of critical information. The Bunkering Safety Check-List contains the following sections:
- Bunkers to be transferred
- Bunker tanks to be loaded
- Checks by Barge prior to Berthing
- Checks prior to Transfer
- Record of repetitive checks
Attention to continuous improvement, to detail and procedure will make for a more efficient operation, a cleaner environment, a safer crew and vessel.
Other critical issues
During the start of the bunker, the pumping rate is kept low. All associated valves positions and tanks are verified for correct order with any leaks in the hose connection. The hose should be properly supported to avoid undue strain on manifolds and rails. Pressure gauge and tank levels must be closely monitored, and associated valves be operated with low flow rate during changing over tanks. A ship crew from the engine is present on the barge to take samples and sounding during the start and end of the transfer process.
Samples must be taken at both barge and ship right at the start of the bunkering operation. The quantity and flow rate of fuel oil is monitored throughout the process from the control room. On completion of loading, all hoses and lines should be drained to the tank or if applicable, back to the barge, prior to disconnection.
Detailed guidelines instructions, guidelines and procedures about bunkering, should be available in the vessel’s Ship Management System (SMS), accompanied by those included in Ship’s Oil Pollution Emergency Plan (SOPEP). A detailed implementation of these procedures and guidance is essential for safe bunkering operations.