Ship Bunkering procedure, stages, accidents and safety precautions have been discussed thoroughly in this article.
What is ship bunkering?
Ship bunkering is a vital process that every ship undertakes at regular intervals with the utmost care. Bunkering operation essentially translates into refilling the fuel tanks or lube oil storage tanks of the vessel. But is it as easy as driving up your car to the gas station?
You guessed it right, it’s not. Ship bunkering is a complex procedure that requires strict adherence to the laid down procedure and involves a certainly high-risk factor. So here’s a detailed insight on bunkering operations in the merchant navy covering the technical aspect, hazards, and the regulatory framework involved with ship bunkering.
Bunkering & Modes of Transfer
The evolution of the word bunkering has a bit of unique history to it. Earlier when steamships used to dominate the merchant navy fleets, coal was used as a source of energy to produce steam which was stored in bunkers onboard ships. Over the years fuels being used in vessels were referred to as bunker fuel and hence the refueling process of ships came to be known as bunkering.
Bunkering operations involve the receiving of bunker fuel or lube oil by the vessels and there are various modes of transfer that carry out this bunkering procedure. The different modes include smaller bunker barges or ships, fuel pipelines, and in some cases even road tankers.
The mode of transfer generally depends on the port facility at which the bunkering takes place, accessibility of the ship, and what kind of fuel is being bunkered. Generally in the case of Heavy Fuel oil (HFO), smaller barges and ships are used whereas for smaller quantities of LNG, lube oil, and MNO direct supply from tankers take place.
Bunkering Operation Procedure
Ship bunkering being a critical operation, the bunkering procedure development and implementation occur in a chain of planned stages to avoid any form of negligence or operational error.
The first stage involves a prior crew meeting, followed by pre-bunkering checklist execution. Before commencement of bunkering procedure, a pre-transfer conference for confirmation regarding the operation between the vessel in charge and barge or port facilities takes place.
As soon as the bunkering starts, continuous monitoring and assessment are undertaken. In the last stage, a post-bunkering checklist is implemented after which confirmation of successful bunkering is communicated. Let’s look into the details of each stage.
STAGE-1 (Crew Meeting)
- The stage is marked by a crew meeting where the detailed bunkering operation plan is developed.
- Bunker fuel requirements are calculated by the engine department and communicated to authorities at shore-based on further voyage plans decided in coordination with the deck department.
- A sequential plan of order in which the fuel tanks are to be filled and their respective volumes to be filled is devised as per the heel and trim of the vessel to be maintained during bunkering.
- The fuel oil and lube oil grades and transfer work along with the piping diagram are agreed upon.
- The positioning of every crew member and their responsibilities during the bunkering operation is decided and clarified
- Identification of emergency plans to be followed in case of any mishap during bunkering.
- In the end, a pre-loading plan notifying all the details of the bunkering operation procedure, discussed and agreed upon, and authorized by the ship’s master is put up in the bunker station.
STAGE-2 (Pre-Bunkering Checklist)
- After arriving close to the port facility, before initiation of the process a thorough pre-bunkering checklist is filled.
- The checklist includes Sounding to be done before bunkering. Sounding refers to the measurement of depth from the surface of the fluid to the bottom of the tank.
- Marking valves and pipes involved in the operation for easy identification
- Confirming that save all trays and all deck scuppers are plugged in
- Ensuring that the overflow tank is empty to prevent spillage in case of excess supply.
- Conforming the operability of overfill alarm.
- presence of red flag or light on the masthead
- All SOPEP (shipboard oil pollution emergency plan) equipment are checked
- Issuing no smoking notice in the proximity of bunkering station
- Ensuring satisfactory working of all pressure gauges and thermometers
- Conducting a leak test of pipeline
- Conforming operability of all valves and gauges along the pipeline
- Ensuring blige line valves are closed.
- Initial trim and heel of the vessel are noted.
STAGE-3 (Pre-Transfer Conference)
- This is the communication between the person in charge of the receiving vessel and that of the bunkering facility before the transfer. This conference is kept as a record in the logbook.
- The confirmation regarding requisitions of the bunker fuel is made like that of quantity, quality, sulfur content, viscosity, and specific gravity.
- The pumping rate of bunker fuel is communicated to the supplying barge/truck
- The hose connection is checked for any kind of leakage
- Communication signals and emergency shut-down procedures are discussed
- Continuous monitoring of flow rates and any abnormalities or leakage is confirmed
- Confirmation of the presence of operable oil spill containment equipment and fire safety equipment is done
- All connections leading to the receiving tanks are again checked and the deck department is notified of the initiation of bunkering.
In the case of tankers and gas carriers, additional safety guidelines need to be abided by, therefore further confirmations are made,
- Radar is turned off along with the Main radio transmitters being earthed.
- Has the AIS system and VHF/UHF transceiver been turned off or regulated to lower power modes?
STAGE-4 (During Bunkering)
- Initially, the pumping rate is maintained at a lower level
- Sounding to verify if the correct tank is being filled is done and after positive confirmation pumping rate is increased.
- Sounding is done at regular intervals and with greater frequency towards the end, close to the final volume till which the tank is to be filled. The safety margin for a tank is generally 90% above which supply of bunker fuel is prohibited.
- Continuous sampling of fuel is also undertaken to ensure satisfactory quality of the bunker fuel supply. Properties like temperature, specific gravity, and viscosity are noted.
- Cautious changing of pipeline network by an order of filling the tanks to avoid spillage.
- Towards the end pumping rate gradually lowered down on instructions of the officer in charge.
STAGE-5 (Post Bunkering)
- The bunkering manifold valve is shut down
- Bunker supply lines are air blown to get rid of any fuel trapped in the pipes
- The Sounding of every tank is done
- Draught and trim of the vessel are noted
- One of the samples of the bunker full story within the MARPOL convention
- Other samples are sent to a lab and until the results are reported back fuel is not taken underuse
- After completion of the bunkering operation, the chief engineer signs a bunkering receipt known as BDN acknowledging the amount and quality of fuel received. A similar entry is made in the logbook.
- In case of any difference of opinion regarding the bunker supplied the chief engineer can issue a note of protest against the supplying authority.
- Lastly on completion, the deck department is notified and signals regarding bunkering are removed.
Accidents and Safety Precautions During Bunkering
A large majority of bunkering operations onboard are successfully conducted without any mishaps and accidents. But in a small fraction of cases, incidents of bunker overflow overboard and oil spillage have been reported, which can also turn into massive fires and cause widespread maritime pollution. Cases of collision during mooring of bunker barges have also occurred causing oil spills.
In a vast number of cases negligence during pre-bunkering inspections and monitoring, impaired communication between the vessels, or poor maintenance of transfer systems onboard are reasons for these accidents. Negligence results in failure to establish a secure pipeline system or inaccurate readings during monitoring and malfunctioning of valves.
Like in the case of AM Ghent causing an oil spill in the Strait of Gibraltar. In case of poor communication collisions and failure to regulate pumping rate may result in oil spills.
Precautions are the only prevention of accidents during bunkering. A full proof plan during crew meets strict adherence to duties, diligent implementation of inspections, and monitoring during bunkering. Establishing a satisfactory level of communication with supplying vessels should be a top priority. All safety protocol equipment including those of fire safety and SOPEP need to be in working condition and accessible to the crew to mitigate any crisis.
Ship bunkering is a critical procedure and this can not be emphasized enough, the slightest error can result in loss of lives, harm to the marine environment, and exorbitant sums of money and it is only correct to say that every step of every stage of bunkering procedure onboard ships are crucial and cannot be compromised for safe and successful bunkering.
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