Section 3 Fuel gas plant and related storage tanks

3.1.1 All equipment (heaters, compressors, vaporisers, filters, etc.) for conditioning the cargo and/or cargo boil off vapour for its use as fuel, and any related storage tanks, shall be located in the cargo or topside areas. If the equipment is located in an enclosed space the space shall be ventilated according to Pt 11, Ch 12, 1.1 Spaces required to be entered during normal cargo handling operations, be equipped with a fixed fire-extinguishing system, according to Pt 11, Ch 11, 1.5 Enclosed spaces containing cargo handling equipment, and with a gas detection system according to Pt 11, Ch 13, 1.6 Gas detection, as applicable.

3.1.2  Provision is to be made to enable the machinery and associated pipework used for preparing and supplying the gas boil-off to be purged of flammable gas prior to being opened up for maintenance or survey.

3.1.3  Gas heaters and compressors, of watertight construction, may be installed on the open deck provided they are suitably located and protected from mechanical damage.

3.1.4  The prime movers for the gas compressors are to be regulated to maintain a positive suction pressure and arranged to stop automatically if the pressure on the suction side of the compressors is lower than 0,035 bar gauge or other approved positive pressure appropriate to the cargo tank system.

3.1.5  The suction and discharge connections to the compressors are to be fitted with isolating valves.

3.2.1 All rotating equipment utilised for conditioning the cargo for its use as fuel shall be arranged for manual remote stop from the engine room. Additional remote stops shall be located in areas that are always easily accessible, typically cargo control room, navigation bridge where applicable and fire control station.

3.2.2 The fuel supply equipment shall be automatically stopped in the case of low suction pressure or fire detection. The requirements of Pt 11, Ch 18, 4.1 General 4.1.1 need not apply to fuel gas compressors or pumps when used to supply gas consumers.

3.3.1 If the heating or cooling medium for the fuel gas conditioning system is returned to spaces outside the cargo area, provisions shall be made to detect and alarm the presence of cargo/cargo vapour in the medium. Any vent outlet shall be in a safe position and fitted with an effective flame screen of an approved type.

3.4.1 Piping or pressure vessels fitted in the fuel gas supply system shall comply with Pt 11, Ch 5 Process Pressure Vessels and Liquids, Vapour and Pressure Piping Systems and Offshore Arrangements.

3.4.2  Pressure vessels for storing methane gas are to be of approved design and fitted with pressure relief valves discharging to atmosphere in a safe position.