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LNG safety

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Sufficient safety barriers must be in place in order to keep the risk within acceptable limits.

Liquefied natural gas has approximately 600 times the energy density of natural gas at atmospheric conditions. LNG is typically stored at a pressure between 1 and 4 bar, whereby the equilibrium temperatures are approximately –160°C to –155°C. In order to minimise the risks related to both property and life, it is vital that the material used for the LNG system has been certified for cryogenic temperatures and that the system has built-in pressure relief functionality.

When designing the vessel, deciding where to place the LNG fuel tank and processing equipment, as well as how to arrange the ventilation ducts and pressure relief masts, and LNG/gas piping in general, must be well thought through. Access to hazardous areas must be arranged in a safe manner and great effort must be put into developing a complete and consistent safety philosophy from the beginning of any vessel design.

The safety philosophy must combine the design and operation of the entire system – from gas bunkering to consumers – and include everything from shut-down functionality to crew awareness. Though not part of the scope of the DNV GL gas-fuelled rule, emphasising the training of crew is also considered paramount.

DNV GL has developed a framework for minimising any risk associated with building gas-fuelled vessels. By reviewing concepts and actual designs against a set of safety criteria included in our rules, DNV GL takes your vessel from the drawing table into operation in a safe and sustainable matter.

Important regulations

Important regulations for the safe application and handling of LNG as ship fuel are:

  • IMO International Code of Safety for Ships using Gases or other Low-flashpoint Fuels (IGF Code ); MSC.391(95), in force since 2017-01-01
  • IMO draft International Code of Safety for Ships using Gases or other Low-flashpoint Fuels (IGF Code)
  • DNV GL rules for gas as ship fuel: 
    • Part 6, Chapter 2, Propulsion, power generation and auxiliary systems
      • Section 5 Gas fuelled ship installations - Gas fuelled
      • Section 6 Low flashpoint liquid fuelled engines - LFL fuelled
      • Section 8 Gas ready ships - Gas ready
    • Part 6, Chapter 5 Equipment and design features
      • Section 14: Gas bunker vessels - gas bunker 
    • DNV GL Recommended Practice RP – G105 on the development and operation of LNG bunkering facilities
  • ISO technical specification for supply of LNG as fuel to ships (ISO TS 18683)