Section 8 Gas turbine package sub-systems

8.1.1 Gas turbine piping systems are, in general, to comply with the requirements given in Vol 2, Pt 7, Ch 1 Piping Design Requirements and Vol 2, Pt 7, Ch 3 Machinery Piping Systems, due regard being paid to the particular type of installation.

8.1.2 The gas turbine design and construction are to minimise the possibility of a fire fed by fuel or lubricating oil leaks.

8.1.3 Any flexible hose assemblies are to comply with Vol 2, Pt 7, Ch 1, 13 Flexible hoses.

8.2.1 Fuel oil arrangements are to comply with the requirements of Vol 2, Pt 7, Ch 3, 3.9 Fuel oil treatment for supply to engines and gas turbines; gas fuel supply arrangements are to comply with the requirements of Vol 2, Pt 7, Ch 1 Piping Design Requirements.

8.2.2 Any high-pressure fuel delivery lines between the fuel pumps and fuel metering valves that are external to the enclosure are to be of double walled construction and are to be capable of containing fuel from a high-pressure line failure to prevent fuel, or fuel oil mist, from reaching a source of ignition on the gas turbine or its surroundings.

8.2.3 Suitable arrangements are to be made for draining/venting any fuel leakage from the protection required by Vol 2, Pt 2, Ch 2, 8.2 Fuel systems 8.2.2 and to prevent contamination of the lubricating oil by fuel oil. An alarm is to be provided to indicate that leakage is taking place.

8.2.4 Means are to be provided to purge the fuel system of air.

8.2.5 Gas turbine fuel system components are to be designed to accommodate the maximum peak pressures experienced in service. Connections on such piping systems should be chosen to minimise the risk of pressurised fuel leaks.

8.2.6 Where more than one gas turbine is supplied from the same fuel source, means of isolating the fuel supply and spill piping to individual engines are to be provided. These means of isolation are not to affect the operation of the other gas turbine(s) and are to be operable from a position not rendered inaccessible by a fire on any of the engines, see also Vol 2, Pt 1, Ch 3 Requirements for Design, Construction, Installation and Sea Trials of Engineering Systems.

8.3.1 Lubricating oil arrangements for the gas turbine system and, where applicable, the alternator, are to comply with the requirements of Vol 2, Pt 7, Ch 3, 8 Lubricating oil systems. They are to be configured to provide adequate flows of lubricating oil to all bearings in the gas turbine unit and, where applicable, the alternator, over the whole range of normal operation and reasonably foreseeable abnormal operating and fault conditions, including start-up and shutdown (run-down) periods.

8.3.2 Where the lubricating oil is circulated under pressure, provision is to be made for the efficient filtration of the oil. At least two filters are to be fitted in the lubricating oil supply lines to the gas turbine and be so arranged that any filter may be cleaned without interrupting the supply of filtered lubricating oil to the gas turbine.

8.3.3 Gas generator and power turbine bearings are to be arranged such that lubrication is not affected adversely by heat flow from adjacent hot parts. Effective means are to be provided for intercepting oil leakage and preventing oil from reaching high temperature glands and casings.

8.4.1 Air cooling and/or ventilation arrangements are to comply with the requirements of Vol 2, Pt 1, Ch 3, 5.9 Ventilation and Vol 2, Pt 1, Ch 3, 5.14 Machinery enclosures.

8.4.2 Cooling water arrangements are to comply with the requirements of Vol 2, Pt 7, Ch 3 Machinery Piping Systems, as applicable.

8.5.1 Turning gear is to be provided to facilitate operation and maintenance of the gas turbine unit as required by the manufacturer.

8.5.2 Gas generator turning gear may be hand-operated where hand operation is practicable. Where turning gear is electrically driven, the motor is to be rated continuously to turn the rotor for an indefinite period with no restrictions. Manuals are to be provided and are to comply with the requirements of Vol 2, Pt 1, Ch 1, 4.6 Through life operation principles 4.6.7.

8.5.3 The turning gear is to be fitted with safety interlocks which prevent gas turbine operation when the turning gear is engaged, see Vol 2, Pt 1, Ch 3, 4.14 Machinery interlocks. Indication of engaged/disengaged is to be provided at all start positions. In the case of hand-operated turning gear, turbine operation may be prevented by manual means, including the provision of warning devices or notices.

8.5.4 The remote control of power-driven turning gear is to be designed so that power is removed if the operating switch is released.

8.5.5 If permanently attached, means are to be provided to secure the turning gear when disengaged.

8.5.6 Overload protection arrangements are to be provided to prevent damage to the turning gear train. Where the turning gear is electrically driven, the protection system is to comply with Vol 2, Pt 10, Ch 1 Ergonomics.

8.6.1 Power take-off shafts coupling the power turbine to the main gearbox/generator are to comply with the requirements for such intermediate shafts given in Vol 2, Pt 3, Ch 2 Shafting Systems, due regard being paid to the particular type of installation.

8.7.1 Drainage arrangements for package components are to link to ship’s drains, taking due account of the materials involved (wash water, fuel, lubricating oil, etc.). Where applicable, those arrangements are not to compromise any requirements to operate the space containing the gas turbine unit at pressures above/below atmospheric ambient.

8.7.2 The ventilation arrangements for the space containing the gas turbine system are to provide sufficient air flow to ensure that the temperatures of components are maintained within the limits specified by the supplier for all normal and reasonably foreseeable abnormal operating and fault conditions.

8.7.3 Where the gas turbine unit is subject to a process of ‘upkeep by exchange’, the lifting arrangements that form part of the installation and/or provisions for the attachment of lifting gear within the installation shall conform to the requirements of a recognised Standard for lifting appliances.

8.7.4 Machinery is to be mounted to provide adequate support against ship motions and relative movement between items of equipment and, where required, protection against shock in accordance with Naval Administration requirements, and to attenuate the transmission of noise and vibration to meet the specified requirements. The requirements of Vol 2, Pt 1, Ch 3, 5.5 Resilient mount, are to be satisfied.

8.8.1 Where the package includes a dedicated fire protection system to protect against fire in the gas turbine unit and its ancillaries, that system is to meet the requirements of Vol 2, Pt 1, Ch 3, 5.15 Fire detection, alarm and extinguishing arrangements.

8.8.2 Where the gas turbine is installed inside a dedicated enclosure, the enclosure boundary is to provide an appropriate level of fire protection, containing/limiting the spread of flames and smoke. An engineering assessment of this boundary demonstrating that the installation meets the levels of fire safety demanded of the ship is to be provided as part of the Assurance Case, see Vol 2, Pt 2, Ch 2, 5.2 Documentation 5.2.10.