UK P&I Club launched a guide providing recommendations and “safe” steps for an efficient LNG bunkering operation, in light of the preparations of the upcoming 2020 sulphur cap.
Although the old-way oil fuel bunkering is a routine, it remains a challenging operation, which is more crucial now, given that LNG bunkering brings additional risks, because of the different methods of bunkering.
LNG bunker hazards
Rollover phenomenon: The process of rapid release of LNG vapour as a result of spontaneous mixing-up of LNG from different densities in one storage tank.
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Rapid phase transition: It represents a very rapid physical phase transformation of liquefied natural gas to vapour, when the LNG meets water. Previous incidents include LNG spills on water.
Vapour dispersion and remote flash fire: The potential for a cloud of gas to burn without the generation of any significant over-pressure. For this to occur, the LNG should first evaporate and then form a concentration of explosive atmosphere between the Lower Flammable Limit (LFL) and the Upper Flammable Limit (UFL) of the methane.
Possible BLEVE (Boiling Liquid Expanding Vapour Explosion): This phenomenon, also known as a fireball, is a sudden release of the pressurised gas caused by a rupture of a tank containing a pressurised liquid above its boiling point
Asphyxiation: A potential release of LNG and the formation of cold gas will result in the gas spreading above the water and on deck. When cold, the methane is heavier than air. Methane is not a poisonous gas; however, it will deplete the oxygen present in the air and will likely cause asphyxiation.
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Low temperature: A leakage will cause severe frostbite or death.
Sloshing: The surge of liquid inside the tank.
Cryogenic damage to steel: A release of LNG, as well as other liquids at temperatures below -40°C can cause serious structural damage to steel and other materials, other than cryogenic steel.
Trapped LNG in bunker transfer pipes and hoses: Where LNG remains trapped and not properly purged with nitrogen, a potential is created for the development of rapid phase transition, pressure build-up, structural failure of the transfer pipe/hose, and the release of the LNG to the atmosphere.
STS LNG transfer operations: All hazards associated with STS LNG transfer operations, such as collision/allision, mooring failure, cargo transfer hose failure, fatigue and availability of personnel, concurrent operations and others.
In addition, the procedures should include:
- Risk assessment for bunker operations
- Bunkering fundamentals and LNGBMP
- Maintenance and testing of bunker transfer equipment
- Emergency response
- Regular drills and training on board ships
Moreover, the guide pays close attention to procedures and steps taken for all states of the bunkering operations.
Specifically, prior to bunkering the procedures must include planning for personnel availability, checks, tests, completion of drills, training and toolbox meetings.
Then, during the bunkering procedure, all those participating should monitor the temperatures, flow, pressure and all bunker transfer sensors, and also periodically test the communication between the bunker supplier and the LNG fueled ship.
When the bunkering operations is finished, interested parties should be careful considering the avoidance of frost bite and inhalation from accidental contact with cold equipment and release of cold nitrogen, and update all documentation prior to the vessel’s departure.
To explore more on the guide, click herebelow
