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GAS SUPPLIES AND GAS DISTRIBUTION SYSTEM Extracts from regulations relating to central system A central system for Acetylene and Oxygen consists of a cylinder store with fittings, piping systems and one or more outlet stations. The various components of the central system are subject to rules laid down by the Norwegian Maritime Directorate or similar organisations, and fittings are required to be of approved types. We quote from the Regulations: – The gas cylinder store shall be a separate room on or above the upper continuous deck. The room shall have bulkheads, deck and deckhead of steel and have a gastight separation from adjacent rooms.

– On drilling platforms and special purpose ships the gas cylinder store may be located on an open deck. – The gas cylinder store shall be insulated, ventilated and so arranged that the temperature does not normally exceed 40°C.

– The ventilation system shall not be connected to any other ventilation system on board.

– The room shall not be used for any other purpose than the storage of gas cylinders.

– Electrical installations in a gas cylinder system shall be of explosionproof types. – Acetylene and Oxygen cylinders shall not be kept in the engine room. – Pipes (on the low-pressure side) shall be seamless, of material ST35 or equivalent, and of wall thickness not less than 2.0 mm. On drilling platforms and special-purpose ships the wall thickness of pipelines on open deck shall be not less than 2.5 mm.

– Pipelines shall be laid with the fewest possible joints. Joints shall be made by butt welds, of good workmanship.

– Connections such as unions, sleeves, flanges etc. are not accepted as alternatives to welding. – Normally, only two outlet stations are allowed for each pipe system from the cylinder store or cabinet. On drilling platforms and special-purpose ships a greater number of outlet stations may be permitted. Approval of the number of outlet stations must be obtained in each individual case. – When the central plant is not in use the gas cylinder valves and other valves shall be shut.

The above points are only extracts from some of the rules relating to central plants in ships. The complete rules are to be found in “Regulations relating to welding equipment etc. for the welding gases Acetylene and Oxygen on board ships, mobile drilling platforms and special-purpose vessels in offshore operations”, issued by the Norwegian Maritime Directorate. A copy of these Regulations can be obtained from Unitor.

Approval and certification of central plants Before a central plant is allowed to be brought into use it must be inspected, degreased, blown through and pressure-tested in compliance with the rules of the Norwegian Maritime Directorate or similar organisations. When the plant is found to be in order an installation certificate is issued, valid for 5 years.

The original of the installation certificate is to be posted in the

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