7 Machinery
Clasification Society 2024 - Version 9.40
Statutory Documents - MCA Publications - The Workboat Code Edition 2 - 7 Machinery

7 Machinery

 7.1 General Requirements

7.1.1 Generally, machinery installations should comply with the requirements given below. Other installations proposed may be specially considered, provided that full information is presented to and approved by the Administration.

7.1.2 The main propulsion machinery and all auxiliary machinery essential to the propulsion and the safety of the vessel should be designed to operate when the vessel is upright and when inclined at any angle of heel and trim up to and including 15 degrees and 7.5 degrees respectively either way under static conditions.

7.1.3 Requirements relating to Air Emissions from engines are addressed in 28.2.5.

7.1.4 A vessel fitted with either a petrol or diesel engine should be provided with an engine suitable for marine use and with sufficient fuel tankage for its area of operation.

7.1.5 A vessel fitted with twin / multiple engine rooms should also be fitted with separate fuel systems and separate electrical and control systems.

7.1.6 A vessel should be provided with sufficient fuel for its intended area of operation, spare portable petrol containers must not be carried on board (containers intended for refuelling a tender are excluded from this, see Chapter 24) unless it is judged to be essential to assure the safe completion of a particular voyage or excursion (see section 7.8).

7.1.7.1 Fuel tanks should be built of steel / stainless steel or other suitable metal to a suitable standard, see Appendix 13. Other materials may be used if they demonstrate equivalent fuel and corrosion resistance and fire resistance to the same standard as that required for the machinery space boundary, where the space is not protected, the tank should be protected against the effect of fire in the machinery space.

7.1.7.2.1 Where a rigid aluminium fuel tank is fitted, it should be built to a suitable standard (see Appendix 13) and it should not normally be installed within the machinery space, nor are they to form part of the boundary of such a space. They should be located in a dedicated, suitably ventilated space. -Where fitting inside the machinery space is unavoidable then it should not contribute any additional fire risk e.g. through the fitting of additional structural fire protection.

7.1.7.2.2 Where a rigid plastic fuel tank is necessary it should not contribute any additional fire risk, it should be built to a suitable standard (see Appendix 13), should not be installed within the machinery space, nor are they to form part of the boundary of such a space. They should be located in a dedicated, suitably ventilated space to prevent the build-up of explosive gases with suitable electrical equipment; NOTE Thermoplastic tanks and components may be affected by high return fuel temperature. It is therefore important for designers and operators to understand the engine installation manual.

7.1.7.3 Fuel spaces shall be ventilated to prevent the build-up of explosive gases. Where petrol tanks are fitted, the requirements of ISO 11105footnote shall be fulfilled. See Appendix 13 and 7.3.1.2.

7.1.8.1 Where it is proposed to use low flash point fuels (other than petrol or diesel), the operator should contact the Administration for guidance early in the project and the proposal shall be supported by a detailed risk assessment. Consideration should be given to safe storage and use of the fuel on board in approved containers using approved pipe systems where appropriate.

7.1.8.2 The operator will need to satisfy the Administration that an appropriate level of safety is provided, which shall include the machinery installation being verified against UK authorised Classification Society standards and being in general compliance with national standards.

7.1.8.3 The operator should take consideration of fuel transportation, carriage, storage ashore, and refuelling operations which shall be in accordance with Health and Safety Executive requirements.

7.2 Diesel Engines

7.2.1 A vessel may be fitted with either an inboard or an outboard diesel engine.

7.3 Petrol Engines

7.3.1 A petrol engine may be accepted provided that the engine is a suitable outboard type.

7.3.1.1 A vessel of any type may be fitted with a small engine (usually less than 4.5 kW) manufactured with an integral fuel tank, provided a safety warning sign is displayed with details of appropriate precautions to be taken when filling the fuel tank.

7.3.1.2 Vessels other than inflatable boats should supply fuel to the engine from either:

  • .1 permanently installed fuel tank/s constructed to an appropriate standard (see Standards Appendix 13) and in the case of vessels fitted with a watertight weather deck shall have arrangements such that spillage during fuel handling will drain into a suitable receptacle to prevent it draining overboard. A vessel’s permanently installed tank/s should not form part of the hull; or

  • .2 if the vessel is less than 8m length or is a vessel with a total power rating of less than 75kW, a separate tank of 55 litres or less with a handle, or two tanks of 27 litres or less, where two outboard engines are fitted, in capacity complying to an appropriate standard (see Standards Appendix 13), provided that the portable tank arrangement is of a suitable proprietary design where the tank meets the securing, ventilation and filling arrangements in 7.5. The tank/s must be fitted with the standard quick connection to the outboard engine without the risk of any spillage and the batteries should be linked by an emergency link isolator or other means of cross-connecting to allow the starting of an engine with a flat battery.

7.3.1.3 Inflatable boats less than 8 m length overall, with engines of less than 15 kW power rating, that do not have an integral fuel tank, should supply fuel to the engine from a separate tank of 27 litres or less in capacity complying with an appropriate standard (see Standards Appendix 13). The tank must be fitted with the standard quick connection to the outboard engine without the risk of any spillage. The securing, ventilation and filling arrangement of this tank should meet the requirements of 7.5.

7.3.2 In locations where an accumulation of hydrocarbon vapours is likely to occur, a suitable hydrocarbon gas detector should be fitted under or adjacent to the tank (located in a safe place). The detector components and any other electrical equipment residing in the vapour area should not be capable of causing ignition.

7.3.3 Attention is drawn to the electrical arrangement requirements (section 8.6).

7.4 Installation

7.4.1 The machinery, fuel tank(s) and associated piping systems and fittings should be of a design and construction adequate for the service for which they are intended, see Appendix 13. These should be installed and protected so as to reduce to a minimum the danger to persons during normal movement about the vessel, with due regard being paid to moving parts, hot surfaces and other hazards.

7.4.2 Special consideration should be given to the design and installation of high pressure fuel pipe systems on diesel machinery to reduce the risk of oil mist fires through failure of the pipes or associated fittings, particularly where they are exposed to excessive temperatures and vibrations.

Mitigations could include the use of double-skinned pipes, shielding, insulation of hot surfaces, proximity and protection of electrical apparatus, anti-vibration measures and fuel oil mist detection or a combination of these measures.

7.4.3 Means should be provided to isolate a source of fuel which may feed a fire in a machinery space. A valve or cock, which is capable of being closed from a position outside the machinery space, should be fitted in the fuel feed pipe as close as possible to the fuel tank.

7.4.4 The recommended material for fuel pipes is stainless steel or equivalent.

7.4.5 Fuel filling and venting pipes should be constructed of fuel compatible, fire resistant, non-kinking material and of sufficient dimensions to prevent spillage during filling.

7.4.6 Fuel pipes should be adequately supported along their entire length especially in way of pipe connections. Consideration should be given for vibrations and the movement of fuel tanks or machinery.

7.4.7 In a fuel supply system, short lengths of flexible fuel pipes may be used where necessary to allow for relative movements and vibration between fuel tanks and fixed fuel pipes or fuel consumers and fixed fuel pipes. Where flexible fuel pipes are introduced, they should be fire resistant/metal reinforced or otherwise protected from fire (see applicable Standards in Appendix 13) and be suitable for the carriage of the chosen fuel. Flexible fuel pipes shall be secured by either metal hose clamps of a non-worm drive type or permanently attached end fittings (e.g. swaged sleeve or sleeve and threaded insert). Where hose clamps are used, the fitting to which the flexible fuel pipe attaches should have a bead, flare, annular grooves or other means of preventing slippage, the anti-slippage arrangement shall not provide a path for fuel leakage.

7.4.8 When flexible fuel pipes are fitted in accordance with 7.4.7 they shall be renewed according to the pipe manufacturer’s instructions. Records of date of fitting and date for renewal shall be kept on board and ashore, where practicable.

7.4.9 Where lengths of conductive materials are used in pipework, consideration should be given to the requirements of Section 8.1.1.

7.4.10 A venting pipe should be led to the open atmosphere, terminating in a position level with or higher than the fuel filling mouth and its open end protected against:-

  • .1 water ingress – by a goose neck or other efficient means; and

  • .2 where there is a risk from flame ingress – by a suitable gauze diaphragm (which can be detached for cleaning).

7.4.11 Fuel filling and ventilation pipes should be arranged to prevent over pressure of the fuel tank systems during filling. As a general guide, a ventilation pipe from a fuel tank intended to be filled by on board transfer pumps or a pressurised system should have a diameter of not less than 1.25 times the diameter of the filling pipe. Small tanks intended to be filled directly by shore fuel line and nozzle may be accepted with a minimum 11mm diameter vent pipe at the top of the tank, if the filling line runs directly and near vertically to the top of the tank and has inside diameter of at least 32mm (solid pipe) or 38mm (hose).

7.4.12 Any fuel vent pipe opening should be not less than 400mm from any ventilation opening through which fuel vapour may enter the vessel.

7.4.13 When the main engine(s) oil fuel system is provided with water separator filter(s) of a type which has plastic or glass bowl(s), it should be located so that it can be easily seen and protected against heat and accidental damage.

7.5 Securing, Ventilation and Filling Arrangements of Petrol Tanks

7.5.1 A separate petrol tank (see section 7.3.1.2.2 and 7.3.1.3) or a spare portable petrol container (see section 7.8) should be secured to the weather deck, in such a way that prevents its movement in a seaway and is able to be quick released in case of a need to jettison. The securing arrangement should also mitigate any risks associated with damage to the tank that could be caused by loose cargo or other equipment. It should also be ventilated and drained into a suitable receptacle to prevent any leakage overboard. The tank/s must not be filled on board or decanted by other means whilst the vessel is at sea.

7.6 Engine Starting and Stopping

7.6.1 An engine should be provided with either mechanical starting, air starting, hand starting or electric starting with independent batteries, or other means of starting acceptable to the Certifying Authority.

7.6.2 When the sole means of starting is by battery, the battery should be in duplicate and connected to the starter motor via a ‘change over switch’ so that either battery can be used for starting the engine. Charging facilities for the batteries should be available. Under normal circumstances it should not be possible to discharge both batteries in parallel.

7.6.3 For air start systems there should be 2 air receivers each with sufficient capacity to allow 6 consecutive starts of a cold engine. Design, maintenance, inspection and test of compressed air start systems should be according to an appropriate Class standard.

7.6.4 All internal combustion machinery, associated ventilation fans, oil transfer pumps, centrifuges etc. should have a secure means of remote stopping from outside the machinery space.

7.6.5 All inflatable boats, boats fitted with a buoyant collar, and open boats that achieve planing speed, including tenders, should be fitted with a kill-cord, to be used at all times during navigation and whilst the engine is on. A spare kill cord should also be carried on board or the kill system should be capable of override to facilitate the rescue of the person going overboard with the cord attached. A vessel that is either fitted with a throttle that is sprung loaded to return to idle or is fitted with a permanent substantial enclosure (see 4.5.2.2) in way of the control position is excluded from the use of kill cords. See also Section 24.

7.7 Portable Equipment

7.7.1 When portable equipment powered by a petrol engine is provided, the unit, unless fully drained of fuel, should normally be stored on the weather deck.

7.7.1.1 Alternatively it may be stowed in a deck locker or protective enclosure which is to the satisfaction of the Certifying Authority and meets the following requirements:

  • .1 vapour tight to the vessel’s interior;

  • .2 not openable from the vessel’s interior; and

  • .3 adequately drained overboard and ventilated to atmosphere.

7.7.1.2 A safety warning sign should be displayed with details of appropriate precautions to be taken when filling the fuel tank.

7.7.2 Gas welding and cutting equipment bottles, if carried, should be stowed in a secure manner on the open deck at a safe distance away from any potential source of fire and should have the capability of being readily jettisoned overboard if necessary.

7.8 Stowage of Spare Petrol

7.8.1 When spare petrol is carried on-board in a portable container/s, for any purpose for use on board the vessel (see 7.1.6), the quantity should be kept to a maximum of two 5 litre containers, the containers should be approved and clearly marked and should normally be stowed on the weather deck where they can readily be jettisoned, where they are ventilated and where spillage will drain directly overboard (see 7.8.2). Any spare portable petrol container/s should meet the securing requirements of 7.5. This section 7.8 does not apply to the carriage of a cargo (as defined in Chapter 29).

7.8.2 In small vessels where section 7.8.1 is not practicable, an approved 5 litre container of petrol may be stowed in a deck locker which meets the requirements of 7.7.1.1.

7.9 Cargo Pipes Carrying Flammable Liquids

7.9.1 Cargo, venting and filling pipes carrying flammable liquids should not pass through accommodation spaces. Where this is unavoidable it may be permitted on the proviso that:

  • Seamless steel pipe is used and it should be as short as possible,
  • Pipe runs within the accommodation space are without joints. However where joints are absolutely necessary for the design of the system, such joints are to be via fully welded sleeves on pipes over 25 mm OD and steel compression fittings approved for the intended service on pipes less than 25 mm OD, the number of compression couplings should be kept to a minimum,
  • Pipes running within accommodation spaces which may be subject to a pressure head should be provided with a means of isolation from tanks providing the pressure head or stopping of supply pumps. The means of isolation or pump stops should be easily accessible from locations within and outside the space,
  • Pumps, piping and associated equipment, which by design are required to be located below a false floor or deck within the accommodation space, are to be separated from the accommodation space by a vapour-proof enclosure or cofferdam which is suitably ventilated and drained with leakage indication providing an audible alarm fitted to the drain. If mechanical ventilation is used, Ex ratedfootnote fans should be such as to avoid the possibility of the ignition of flammable vapour/air mixtures,
  • After installation on board, pipe systems are to be tested at 1.5 times the working pressure, but not less than 3.5 bar to the satisfaction of the Certifying Authority,
  • Hydrocarbon (HC) gas/vapour detection is fitted within the vapour-proof enclosure or cofferdam,
  • Where pipes are required to pass through bulkheads, decks or deckheads, these penetrations are to be sealed with an approved bulkhead gland with the penetration insulated in accordance with the required bulkhead division or class, and
  • Pipes behind linings may be considered as acceptable provided they are within a vapour-proof enclosure.

7.10 Air Receivers

7.10.1 Where a vessel is fitted with air receivers in machinery spaces or other high fire risk areas, the system should be arranged such that any release of air through the pressure relief valves or bursting discs, that may occur during a fire, is vented to the open air and not within that space, unless the volume of free air which could be released is taken into account in the calculation for quantity of firefighting medium required. Installation of any fixed fire fighting system should be fitted in accordance with 15.6.3. See also 7.6.3.


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