( SOLAS reg. II-2/15, MSC/Circ.851 )
1 The Maritime Safety Committee, at its sixty-third session (16 to 25 May 1994), approved Guidelines to Minimize Leakages from Flammable Liquid Systems, set out at annex to the present circular, as prepared by the Sub-Committee on Ship Design and
Equipment at its thirty-seventh session.
2 Member Governments are invited to bring the Guidelines and the measures that should be taken to reduce fires originating from machinery space flammable oil systems to the attention of designers, shipyard personnel, engine-room personnel, owners, operators and
maintenance personnel.
Annex
GUIDELINES TO MINIMIZE LEAKAGES FROM FLAMMABLE LIQUID SYSTEMS
1 OVERVIEW
1.1 Purpose
.1 The International Maritime Organization recognizes that oil fuel, lubricating oil and other flammable oil system failures are a major source of shipboard fires.
.2 These guidelines, including appendices, are developed to assist designers, shipyard personnel, engine-room personnel, owners, operators and maintenance personnel to
be aware of measures that should be taken to reduce fires originating from machinery space flammable oil systems.
1.2 Scope
.1 The status of the guidelines is that of a recommendation. Attention is drawn to the importance of the design, construction, testing, installation, maintenance and inspection of systems containing flammable oils in order to reduce the risk of fire.
.2 The guidelines supplement the regulation II/2-15, "Arrangements for oil fuel,
lubricating oil and other flammable oils", of the International Convention for the Safety of Life at Sea (SOLAS 74), as amended, and are applicable to new and existing ships, including non-convention ships and ships covered by instruments other than SOLAS Convention.
.3 The guidelines have been developed without prejudice to the requirements of existing SOLAS regulations, MSC circulars, or other IMO safety instruments.
Appendix 01 General Piping System Considerations
1Introduction
Based on past experience, it is known that the combination of combustible and
flammable materials and sources of ignition is the main cause of machinery space fires. The combustible and flammable materials involved in the majority of cases are oils, i.e., oil fuel, lubricating oil, thermal oil, or hydraulic oil.
There are many potential ignition sources in a machinery space, the most common being hot surfaces, e.g., exhaust pipes and steam pipes. Overheating of machinery, ignition from electrical installations due to short-circuiting or arcing of switchgear and other fault conditions may result in fire. Other frequent ignition sources are those associated with human activities, e.g., smoking, welding, and grinding.
2Human element
The role of the human element should always be considered and personnel involved should be properly trained and follow established procedures.
3 Inspection, maintenance and repairs
Inspection, maintenance and repairs should be carried out in a professional manner.
Owners should ensure that this is done and that the necessary skills, equipment and spares are available.
4Operations
4.1 Many fires have been caused by pipe connections and fittings working loose. The fuel, lubricating and hydraulic oil pipes, their fittings, connections and securing arrangements should be routinely checked. Care should be taken not to overtighten fittings during these checks.
4.2 When maintenance or repair to the main or auxiliary engines has been carried out checks should be made to ensure that the insulation covering the heated surfaces has been properly replaced. A regular check of the engines should be made to confirm that the
insulation is in place.
4.3 Any fuel, lubricating or hydraulic oil leakages should be dealt with promptly. The screening arrangements and pipe securing devices should be kept in good order.
4.4 Serious fires have originated because of a failure to recognize potential hazards, such as burning oil running out of furnace fronts onto the tank top, a spray of oil from a defective gland, joint or a fractured pipe, in areas where these may not be readily noticeable but may be easily ignited. It is essential to avoid the dangerous situation in which a small fire could spread to waste oil in the bilges or on tank tops where it could rapidly spread out of control. Cleanliness is essential for safety and a high standard of cleanliness should always be maintained.
4.5 Woodwork or other readily combustible materials should not be used in boiler rooms and machinery spaces where oil fuel is used. No combustible material should be stored near any part of the oil installations. The use of bituminous or similar flammable compounds should be kept to a minimum in machinery and boiler spaces.
4.6 When repairs, however temporary, are carried out to oil lines, special attention must be paid to fire risks. All repairs, even temporary ones, should be adequate to prevent any danger of leakage and should be to a standard which would endure exposure to fire.
4.7 If there is a leakage of fuel, lubricating or hydraulic oil the chances of preventing the outbreak of fire or quickly extinguishing one which has started will be greatly improved if all affected or adjacent machinery which may have heated surfaces, including ancillaries, can be immediately shut down. The prevention of further leakage will reduce the probability of fire or reduce the intensity of one which has already started and may help to avoid permanent disablement of the ship.
Appendix 02 Flexible Hose and Flexible Hose Assemblies
1 Scope
SOLAS Regulations II-2/15.2.8, II-2/15.3, II-2/15.4 permit the limited use of flexible
pipes in fuel oil, lubricating oil and other flammable oil systems. This appendix provides
guidance in complying with these regulations.
2 Application
Flexible pipes or hose assemblies, which are flexible hoses with end fittings attached, should be in as short lengths as practicable and only used where necessary to
accommodate relative movement between fixed piping and machinery parts.
3 Design and construction
Hoses should be constructed to a recognized standard and be approved as suitable for the intended service, taking into account pressure, temperature, fluid compatibility and mechanical loading including impulse where applicable. Each hose assembly should be
provided with a certificate of hydrostatic pressure testing and conformity of production.
4 Installation
Hoses should be installed in accordance with the manufacturers instruction, having regard to: minimum bend radius, twist angle and orientation, also support where necessary. In locations where hoses are likely to suffer external damage, adequate protection should be provided. After installation, the system should be operated at maximum pressure and
checked for possible malfunctions and freedom from leaks. General installation guidelines are given in figures 2.1 and 2.2.
5 Inspection and maintenance
Hose assemblies should be inspected frequently and maintained in good order or replaced when there is evidence of distress likely to lead to failure. Any of the following conditions may require replacement of the hose assembly:
.1 leaks at fitting or in flexible hose;
.2 damaged, cut, or abraded cover;
.3 kinked, crushed, flattened, or twisted flexible hose;
.4 hard, stiff, heat cracked, or charred flexible hose;
.5 blistered, soft, degraded, or loose cover;
.6 cracked, damaged, or badly corroded fittings;
.7 fitting slippage on flexible hose.
It is expected that hose assemblies may need to be replaced several times in the life
of the ship. Manufacturer's recommendations should be followed in this respect. However
hoses should be replaced in good time whenever there is doubt as to their suitability to
continue in service.
02.01 Metallic Flexible Host General INstallation Guidelines
02.02 Non-metallic Flexible Hose General Installation Guidelines
Appendix 03 Spray Shields
1 Scope
SOLAS regulations II-2/15.2.11, II-2/15.3 and II-2/15.4, require oil fuel, lubricating
oil and other flammable oil piping to be screened or otherwise suitably protected to avoid as far as practicable oil spray. This appendix provides guidance to comply with these regulations.
2 Application
Spray shields are intended for use around flanged joints, flanged bonnets and any
other flanged connection in oil pressure systems which are located above the floor plates and which have no insulation in way of the joints. The purpose of spray shields is to prevent the impingement of leaked or sprayed flammable liquid onto a hot surface or other source of ignition. (Refer to appendix 7, guidance for insulation of hot surfaces.)
3 Design
Many types of spray shields are possible and they need not necessarily be attached to the joint, or totally enclose the joint. An example of a spray shield which provides a
total enclosure is given in figure 3.1. This spray shield is designed to wrap completely around the joint and is long enough to provide an overlap equal to one-quarter of the joint's circumference. The shield is wrapped around the sides of the flange far enough to cover the heads of the bolts. The finished width is equal to or exceeds "A+B+A". The shield is laced tightly with wire and the overlap is pointed away from potential ignition
sources.
4 Inspection and maintenance
Spray shields should be inspected regularly for their integrity and any which have
been removed for maintenance purposes should be refitted on completion of the task.
Appendix 04 Jacketed High Pressure Fuel Lines
1 Scope
SOLAS regulation II-2/15.2.9 requires all external high pressure fuel delivery lines
between the high pressure fuel pumps and fuel injectors to be protected with a jacketed piping system capable of containing fuel from a high pressure line failure. A jacketed pipe incorporates an outer pipe into which the high pressure fuel pipe is placed forming a permanent assembly. The jacketed piping system is to include a means for collection of leakages and arrangements are to be provided for an alarm to be given of a fuel line failure. Regulation II-2/15.2.12 will require existing ships to retrofit engines having an
output greater than 375 kW.
2 Design
Two systems have been successfully used in meeting this requirement, namely, rigid
sheathed fuel pipe and flexible sheathed fuel pipe. In either case the sheathing is to fully
enclose the pipe and is to resist penetration by a fine spray or jet of oil from a failure in the pipe during service. Also the annular space and drainage arrangements should be sufficient to ensure that in the event of complete fracture of the internal pipe, an excessive build up of pressure cannot occur and cause rupture of the sheath. The suitability of such pipes should be demonstrated by prototype testing. The drainage arrangement should prevent contamination of lubricating oil by fuel oil.
3 Inspection and maintenance
Regardless of the system selected, little additional maintenance or periodic inspection is required to keep the jacketed fuel lines in proper working order. However, jacketed
pipes should be inspected regularly and any drainage arrangement which may have been
disconnected for maintenance purposes should be refitted on completion of the task.
Appendix 05 Bellows Expansion Joints
1 Scope
This appendix covers metallic bellows expansion joints. Nonmetallic expansion joints
are not addressed since their use is generally limited to water systems. To ensure adequate
piping system flexibility, bends, loops, offsets or bellows expansion joints are required in most piping systems.
2 Design
Expansion joints are designed to accommodate axial and lateral movement and should not be used to compensate for pipe misalignment. Design may be based on an acceptable code or on testing of expansion joints of similar construction, type, size and use. Thermal expansion and contraction and the fatigue life due to vibration are also important points to consider. Where external mechanical damage is possible, the bellows should be suitably protected. Each bellows expansion joint should be provided with a certificate of hydrostatic pressure testing and conformity of production.
3 Installation
The bellows expansion joints should be installed in accordance with the manufacturer's instructions and examined under working conditions.
4 Inspection and maintenance
Bellows expansion joints should be inspected regularly and be replaced whenever
there is doubt as to their suitability to continue in service.
Appendix 06 Filters and Strainers
1 Scope
This appendix covers filters and strainers used in fuel oil, lubricating oil or other
flammable oil systems having metallic housings and bodies with a melting point above 930
degrees C. Other housing and body materials are not addressed and their use should be specially considered on a case by case basis in relation to the risk of fire.
2 Design
All pressure retaining parts should be suitable for the maximum operating temperature
and pressures. The filter or strainer design and construction should facilitate cleaning and
prevent or minimize spillage during maintenance. Filters and strainers should be designed such that they cannot be opened when under pressure.
3 Installation
Filters and strainers should be located as far away as practicable from hot surfaces and other sources of ignition. They should not be located in positions where spillages
could fall onto the flywheel or other rotating machinery parts and be sprayed around.
Suitable drip trays should be provided under filters and strainers.
4 Inspection and maintenance
Filters and strainers should be inspected every time they are opened for cleaning and the cover gaskets or seals should be renewed when necessary. Satisfactory seating and tightening of the cover should be verified before the system is put back into service.
Appendix 07 Insulation
1 Scope
SOLAS regulations II-2/15.2.10, II-2/15.3 and II-2/15.4 require that all surfaces with temperatures above 220 degrees C (430 degrees F), which may be impinged as a result
of a fuel oil, lubricating oil and other flammable oil system failure be properly insulated. This appendix provides guidance to comply with these regulations.
2 Purpose
Insulation of hot surfaces is primarily to reduce the risk of fire by reducing temperatures of surfaces below the auto-ignition temperature of oil fuel, lubricating oil or other flammable oils.
3 Installation
Manufacturers' instructions should be followed if available. Permanent insulation should be used to the greatest extent possible. Insulation should be provided with readily removable sections to allow access for normal maintenance. Where the insulation used is oil absorbent or may permit the penetration of oil, the insulation should be encased in steel sheathing or equivalent material.
4 Inspection and maintenance
A regular check of equipment should be made to confirm that the insulation is in place. When maintenance or repair to equipment has been carried out, checks should be made to ensure that the insulation covering the heated surfaces has been properly replaced.
Appendix 08 Pressure, Temperature and Oil Level Gauges
1 Scope
SOLAS regulation II-2/15.2.6 contains requirements for oil level gauges. This
appendix gives guidance to comply with this regulation and addresses pressure and
temperature gauges and similar instrumentation which have featured in many fires aboard
ships.
2 Design and installation
All pressure gauges and other similar instruments in oil systems should wherever
possible be fitted with an isolating valve or cock at the connection to the pressure take off
point. The number of pressure take off points should be kept to a minimum and gauge
piping runs should be as short as practicable. Copper pipes may be joined by brazing but
soldered connections should not be used in oil systems.
Temperature gauges in oil systems should be fitted into a fixed pocket (thermowell).
Oil level gauges should be of a design which is approved for the intended service. The installation of level gauges into the lower part of oil tanks is prohibited under SOLAS for passenger ships, and is discouraged for cargo ships. Suitably protected gauges having heat resistant flat glass of substantial thickness and self-closing fittings at each tank connection may be fitted to oil tanks in cargo ships. Round gauge glasses are not permitted.
3 Inspection and maintenance
Copper gauge piping is particularly sensitive to work-hardening. All gauge pipes and
fittings should be regularly inspected and maintained in good working order.
Appendix 09 Pipe Connectors, Joints, Hangers and Supports
There are many different types of pipe connectors and joints, some of which are not considered suitable for oil systems. In general, flanged joints conforming to recognized
standards should be used. Compression fittings and other types of connectors should be
approved for the intended service. The number of joints should be kept to a minimum in
oil systems.
Pipes in oil systems should be adequately supported. Supports or hangers should not be used to force alignment of piping or system components where the alignment is
incorrect. Any hangers or supports which have been removed for maintenance purposes should be refitted when the task is completed.