Section 8 Piping

8.1.1 Fuel oil and hydraulic oil piping systems arrangements are to comply with Pt 5, Ch 12 Piping Design Requirements and Pt 5, Ch 14 Machinery Piping Systems as applicable.

8.1.2 Engine fuel system components are to be designed to accommodate the maximum peak pressures experienced in service. Where fuel injection pumps are fitted, particular attention is to be given to the fuel injection pump supply and spill line piping which may be subject to high-pressure pulses from the pump. Connections on such piping systems should be chosen to minimise the risk of pressurised fuel oil leaks. Fatigue analysis may be considered necessary to establish the suitability of the piping system components for the pressures and fluctuating stresses that the pipe system may be subject to in normal service.

8.1.3 On engines used for propulsion, where fuel oil and hydraulic oil pressure pumps are fitted, and these are essential for engine operation, not less than two fuel oil and two hydraulic oil pressure pumps are to be provided and arranged such that failure of one pump does not render the other pump(s) inoperative. Each fuel oil pump and hydraulic oil pump is to be capable of supplying the quantity of oil for engine operation at its maximum continuous rating and arranged ready for immediate use.

8.1.4 External high-pressure fuel delivery piping between the fuel injection pump or high-pressure fuel pumps and fuel injectors is to be protected with a jacketed piping system capable of containing leakage and/or spray of flammable fluid from a high-pressure line failure. The jacketed piping arrangements are to be approved, see Table 2.1.1 Plans and particulars to be submitted. The protection of high-pressure fuel pipes on common rail fuel systems will be specially considered.

8.1.5 The protection required by Pt 5, Ch 2, 8.1 Fuel oil, hydraulic and high pressure oil systems 8.1.4 is to prevent fuel oil or fuel oil mist from reaching a source of ignition on the engine or its surroundings. Suitable drainage arrangements are to be made for draining any fuel oil leakage one or more collector tank(s) fitted in a safe position. These tanks are to be separate from any tank used to collect other oils such as lube oil or hydraulic oil to prevent cross contamination. An alarm is to be provided to indicate that leakage is taking place. The collector tank arrangement is to be approved. .

8.1.6 Hydraulic oil pressure piping between the high-pressure hydraulic pumps and hydraulic actuators is to be protected with a jacketed piping system or suitable enclosure capable of containing hydraulic oil leakage from a high-pressure pipe failure. Where flammable oils are used in high-pressure systems to operate exhaust valves, the oil pipe lines between the high-pressure oil pump and actuating oil pistons are to be protected with a jacketed piping system capable of preventing oil spray from a high-pressure line failure.

8.1.7 All lubricating and hydraulic oil pipes, and fuel oil pipes that are not jacketed or enclosed, are to be suitably installed and screened to avoid oil spray or leakage onto hot surfaces, see also Pt 5, Ch 14, 2.9 Precautions against fire 2.9.2, Pt 5, Ch 14, 8.15 Precautions against fire 8.15.2 and Pt 5, Ch 14, 9.7 Precaution against fire 9.7.2 as applicable.

8.1.8 Where flammable oils are used in high-pressure actuating systems, a fatigue analysis is to be carried out in accordance with a suitable standard and all anticipated pressure, pulsation and vibration loads are to be considered. The analysis is to demonstrate that the design and arrangements are such that the likelihood of failure is as low as reasonably practicable. The analysis is to identify all assumptions made and standards to be applied during manufacture and testing of the system. Any potential weak points which may develop due to incorrect construction or assembly are also to be identified.

8.1.9 Accumulators and associated high-pressure piping are to be designed, manufactured and tested in accordance with a standard applicable to the maximum pressure and temperature rating of the system.

8.1.10 For high-pressure oil containing and mechanical power transmission systems, the quality plan for sourcing, design, installation and testing of components is to address the following issues (see Table 2.1.1 Plans and particulars to be submitted, Note 11):

1. Design and manufacturing standard(s) applied.

2. Materials used for construction of key components and their sources.

3. Details of the quality control system applied during manufacture and testing.

4. Details of type approval, type testing or approved type status assigned to the machinery or equipment.

5. Details of installation and testing recommendations for the machinery or equipment.

8.2.1 Vessels of less than 500 gross tons and which are not required to comply with the SOLAS - International Convention for the Safety of Life at Sea, are to be capable of maintaining adequate manoeuvring capability.

8.2.2 Where multi-engined installations are supplied from the same fuel source, means of isolating the fuel supply and spill piping to individual engines is to be provided. These means of isolation are not to affect the operation of the other engines and are to be operable from a position not rendered inaccessible by a fire on any of the engines.

8.3.1 Where the surface temperature of the exhaust pipes and silencer may exceed 220°C, they are to be water cooled or efficiently lagged to minimise the risk of fire and to prevent damage by heat. Where lagging covering the exhaust piping system including flanges is oil-absorbing or may permit penetration of oil, the lagging is to be encased in sheet metal or equivalent. In locations where the Surveyor is satisfied that oil impingement could not occur, the lagging need not be encased.

8.3.2 Where the exhausts of two or more engines are led to a common silencer or exhaust gas-heated boiler or economiser, an isolating device is to be provided in each exhaust pipe.

8.3.3 For alternatively fired furnaces of boilers using exhaust gases and fuel oil, the exhaust gas inlet pipe is to be provided with an isolating device and interlocking arrangements whereby fuel oil can only be supplied to the burners when the isolating device is closed to the boiler.

8.3.4 In two-stroke main engines fitted with exhaust gas turbo-blowers which operate on the impulse system, provision is to be made to prevent broken piston rings entering the turbine casing and causing damage to blades and nozzle rings.

8.3.5 Where the exhaust is led overboard near the waterline, the exhaust system shall be so designed as to prevent water from entering the engine exhaust manifold through wave or wake action, both when the engine is in operation or shutdown. The system shall also be designed to prevent ingress of water at the angles of inclination as shown in Pt 5, Ch 1, 3.7 Inclination of ship.

8.3.6 Where the exhaust is cooled by water spray, the exhaust pipes are to be self-draining overboard. Suitable measures shall be taken to prevent inadvertent closure of drain valves where this may lead to sprayed water entering the engine. Means shall be provided to prevent water from flowing back into the engine when the engine is stopped.

8.3.7 Exhaust systems having components sensitive to heat shall be fitted with a high temperature alarm after water injection. This alarm shall be integrated into the ship’s alarm system.

8.3.8 Exhaust pipes penetrating the shell below the bulkhead deck shall be provided with a shipside valve or other approved positive means of closure at the shell to prevent back-flooding into the hull through a damaged exhaust system.

8.3.9 The exhaust system shall be designed such that the exhaust back-pressure is within the allowable limits stated by the engine manufacturer under all expected operating conditions.

8.4.1 In designing the compressed air installation, care is to be taken that the compressor air inlets will be located in an atmosphere reasonably free from oil vapour or, alternatively, an air duct from outside the machinery space is to be led to the compressors.

8.4.2 The air discharge pipe from the compressors is to be led direct to the starting air receivers. Provision is to be made for intercepting and draining oil and water in the air discharge for which purpose a separator or filter is to be fitted in the discharge pipe between compressors and receivers.

8.4.3 The starting air pipe system from receivers to main and auxiliary engines is to be entirely separate from the compressor discharge pipe system. Stop valves on the receivers are to permit slow opening to avoid sudden pressure rises in the piping system. Valve chests and fittings in the piping system are to be of ductile material.

8.4.4 Drain valves for removing accumulations of oil and water are to be fitted on compressors, separators, filters and receivers. In the case of any low-level pipelines, drain valves are to be fitted to suitably located drain pots or separators.

8.4.5 The starting air piping system is to be protected against the effects of explosions by providing an isolating non-return valve or equivalent at the starting air supply to each engine.

8.4.6 In direct reversing engines bursting discs or flame arresters are to be fitted at the starting valves on each cylinder; in non-reversing and auxiliary engines at least one such device is to be fitted at the supply inlet to the starting air manifold on each engine. The fitting of bursting discs or flame arresters may be waived in engines where the cylinder bore does not exceed 230 mm.

8.4.7 Alternative safety arrangements may be submitted for consideration.