Section
8 Piping
8.1 Fuel oil and hydraulic and high pressure
oil systems
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 1.1.1 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 10, Ch 1, 8.1 Fuel oil and hydraulic and high pressure oil systems 8.1.10 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 to one or more collector tanks 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 15, Ch 3, 4.11 Precautions against fire 4.11.1 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. 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 (Table 1.1.1 Plans and particulars to be submitted,
Note 11:
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Design and manufacturing
standard(s) applied.
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Materials used
for construction of key components and their sources.
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Details of the
quality control system applied during manufacture and testing.
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Details of type
approval, type testing or approved type status assigned to the machinery
or equipment.
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Details of installation
and testing recommendations for the machinery or equipment.
8.2 Additional requirements for fuel oil, hydraulic and high pressure oil systems for special service craft
8.2.2 Where multi-engine installations on board special service craft required
to comply with the SOLAS - International Convention for the Safety of Life at Sea and yachts that are of 500 gt or more
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.
8.2.3 Where fuel treatments, additives or emulsified fuel are used as a means
of abating exhaust emissions, engines and fuel systems are to be compatible with
such additives, treatments and emulsified fuel.
8.3 Exhaust systems
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 shut down. The
system shall also be designed to prevent ingress of water at the angles of inclination
as shown in Pt 9, Ch 1, 4.2 Inclinations of the craft.
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 craft’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 Additional exhaust system requirements
8.4.1 Engine inlets are to be arranged to provide sufficient air to the engines
whilst minimising the ingestion of harmful particles.
8.4.2 The arrangement of the exhaust system is to be such as to prevent exhaust
gases being drawn into the manned spaces, air conditioning systems and air intakes.
They should not discharge into air cushion intakes.
8.4.3 For small service craft not required to comply with the HSC Code, where
the lowest point of the exhaust outlet is well above the waterline, alternative
arrangements to those specified in Pt 10, Ch 1, 8.3 Exhaust systems 8.3.8 may be submitted for consideration. Details of
the alternative arrangements are to be included in the documentation required by
Pt 10, Ch 1, 1.4 Submission requirements and are to demonstrate:
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equivalence to Pt 10, Ch 1, 8.3 Exhaust systems 8.3.8 is achieved; and
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compliance with the applicable statutory requirements of the
National Authority of the country in which the craft is to be
registered.
8.5 Starting air pipe systems and safety fittings
8.5.1 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.
8.5.2 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.
8.5.3 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.
8.5.4 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.
8.5.5 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.
8.5.6 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.
8.5.7 Alternative
safety arrangements may be submitted for consideration.
8.6 Emissions abatement systems
8.6.2 Where fuel treatments, additives or emulsified fuel are used as a means of abating
exhaust emissions, engines and fuel systems are to be compatible with such
additives, treatments and emulsified fuel
8.6.3 Where chemicals or substances are injected into the exhaust gas flow
before engine turbo-charger(s) or emissions abatement equipment, this is not to
present a risk of damage, chemical attack or performance degradation to the
turbo-charger(s) or emissions abatement equipment.
8.6.4 Where emissions abatement equipment is installed as part of the exhaust
system, the exhaust system is to be capable of safely transmitting the minimum and
maximum exhaust gas flows also with the emissions abatement equipment out of
operation.
8.6.5 Where emissions abatement equipment is to be installed as part of the
exhaust system, the resulting exhaust gas system back pressure is to remain within
the allowable limits stated by engine manufacturer, and a means of measuring
differential pressure across the emissions abatement equipment is to be provided.
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