1 - FIREFIGHTING

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Shetland StudiesFirefighting

School

of

Nautical

Fire Prevention And Sources Of Ignition On Ships Fire is a danger that never rests and one that is often due to carelessness. The basis of fire prevention is the elimination of the hazard. A determined effort to reduce flammable material can go a long way towards this aim. Cleanliness and tidiness are the best protection against fire. Loose cotton material left lying about instead of being stowed away provides kindling to carelessly discarded matches or cigarette ends. Areas of the no cigarette smoking rule must be strictly adhered to. Oily waste should not be allowed to accumulate. Accumulation of oil bilges should not be tolerated. Tank tops and bilges should be kept clear and oil free. There are certain prime sources of heat from which combustible material must be kept separate: Boilers, Internal Combustion or steam driven machinery. Steam pipes Radiators Galley ranger and ovens Hot water boilers Boiler uptakes and Funnel casings Galley uptakes and exhaust pipes Workshop welding area Rags, waste, clothing or anything that will burn should not be stowed near these items. The machinery may be cool initially but when brought on line may cause a fire. Carelessly carried out maintenance often gives rise to a source of heat which is undetected may cause a fire. Examples are: Poor insulation on wandering electrical leads Glands in rotating spindles too tight. Badly adjusted brush gear in electric motors causing sparking. Badly fitted bearings, insufficient lubrication and similar neglect by maintenance staff. Damaged electrical insulation of multicore cables fitted to portable equipment, allowing leads to become exposed, resulting in short circuiting. Heavily painted Main Engine parts which connect directly to a source of high temperature. Electrical Fires With few exceptions, fires of electrical origin occur due to a lack of reasonable care in the maintenance and use of electrical equipment. The power which drives electric motors and provides heat and light is capable of igniting its insulation or any combustible material near by. All electrical equipment should be properly installed, maintained and operated. The most common causes of electrical fires are: Failure of insulation causing short circuits or discharge to earth. Overheating of cable or equipment due to overloading, lack of ventilation or local overheating. Ignition of flammable substances by electrostatic discharges. Misuse of electrical equipment which in itself is not actually defective. Switchboard fires due to loose connections, faulty contactors or loose bus-bar retaining bolts. Safeguards are: All equipment should be installed correctly and only used for specific function that it is designed for. Regular electrical and mechanical maintenance should be carried out including insulation readings and cleanliness. All overload devices should be tested regularly. Switchboard chattering contactors to be repaired or replaced. Regular inspection of the switchboard internal connections to be carried out.WRHunter Underpinning Knowledge

1

Shetland StudiesFirefighting

School

of

Nautical

Spontaneous Combustion Spontaneous combustion can occur when packed cargoes such as coal, hemp, copra, grain etc. are carried especially if these are in a damp condition when loaded. In the centre of these cargoes there is very little ventilation to supply a cooling effect and the natural heat generated can build up to such a degree that it causes combustion of the material. Due to the restriction of oxygen supply this will just smoulder for a considerable time until part of the cargo is removed. Then by admitting additional air the cargo will burst into flames. Stowage of engine room stores is important since materials such as cleaning rags, cotton waste, sawdust etc. can all give rise to spontaneous combustion especially if they are stored next to the various chemicals now carried on board ships. Unattended oil leakage dripping on to hot pipes can ignite and cause fires. The disposal of used dry cell batteries must be carried out in a careful manner. Causes Of Ignition On Board Ship Fire and explosion cannot occur unless a source of ignition is applied to a fuel in the presence of oxygen. The potential fire hazard on board any ship varies as the type of ship and the cargo carried. Though all are covered by the same regulations, the observance of these regulations may be stricter and vary slightly from one ship to another. Smoking Smoking on board ship can be dangerous but smoking in prohibited places endangers all lives on board. In some ports the local authorities prohibit smoking anywhere on board particularly with vessels carrying flammable cargoes. More usually one smoking area is allocated, nominated either by company regulations or by the Master. Smoking in bed is a perpetual hazard especially after the consumption of alcohol. Numerous deaths have resulted from this habit due to people falling asleep with lighted cigarettes and setting the bedding on fire. This offence often leads to dismissal. Cigarette lighters are banned on some vessels due to their ability to operate when dropped therefore they should never be carried in a pocket. Many companies provide safety matches Torches All electric torches on board should be of an approved type and are usually provided on the vessel. Unless the type of torch has been approved by the appropriate certification authority there is a danger of sparking when the switch makes and breaks. Also the possibility of an ignition source if the torch should be accidentally dropped breaking the bulb. This would be particularly dangerous in a gas filled atmosphere. There are a wide variety of approved torches available which range from being gas tight, explosion proof to being classified as intrinsically safe. or use on board. Domestic Equipment Electric shavers, radios and galley appliances can all produce sparks of sufficient intensity to ignite flammable vapour and material. Probably the most common source of fire in galley equipment is the thermostatically controlled fryer. If the high temperature cut-out fails to operate and if the unit is not "fail-safe" then the fat or oil in the unit can overheat and burst into flames. When installing domestic electrical equipment on board ship it is advisable to consider all safety features of the unit as the most important factor. Regular inspection and maintenance must be carried out. Any build up fat residues must be avoided, especially underneath the cooking hobs on the galley range. Oil Fires Oils and vapours given off from all hydrocarbon oils contain the combustible elements of hydrogen and carbon which if temperature and pressure conditions are correct will ignite in the presence of oxygen. Steam heating coils are fitted to some oil tanks to assist in the separation of water and also serve to keep the oil in a preheated condition and reduce its viscosity for easier pumpingWRHunter Underpinning Knowledge

2

Shetland StudiesFirefighting

School

of

Nautical

and atomisation. The temperature is kept between 38.5 - 43.5C and the maximum temperature permitted is 53.5C. This limit is necessary because of the fire risk due to formation of oil vapour during heating. The minimum closed flashpoint for oil under storage is 66.5C. Great caution is required when filling any settling or other oil tank to prevent overflowing, especially in machinery spaces where exhaust pipes or other hot surfaces are directly below Particular care should be taken when filling tanks which have their sounding pipes in the machinery space to ensure that weighted cocks are closed. Under no circumstances should a weighted cock on a fuel tank or lubricating oil tank sounding pipe or on a fuel, lubricating or hydraulic oil tank gauge be secured in the open position. All Main Engine high pressure pipes to be secure with no leakage. Fire has occurred, when the paint on a recently fitted Air Start Valve caught fire, and came in contact with a leaking Fuel Pump connection. Precautions Against Fire And Explosion While Welding Before welding, flamecutting or other hot work, a check should be made that there are no combustible solids, liquids or gases present or adjacent to the area of hot work. Welding or other hot work should never be undertaken on items covered with grease, oil or other flammable materials. The vessel should have a permit to work system in force, this will include a Hot Work Permit, prior to starting any hot work on board, a responsible person is to complete and sign a Hot Work Permit, inspected and signed by the Master of the vessel. The permit is to be kept at hand at the place of work. When welding is to be carried out in the vicinity of open hatches, suitable screens should be erected to prevent sparks dropping down the holds. Where necessary combustible materials and dunnage should be moved to a safe distance before commencing operations. Port holes and other openings through which sparks may fall should be closed where practicable. Where work is being carried out close to or at bulkheads, decks or deckheads, the remote sides of the divisions should be checked for materials and substances which may ignite and for cables, pipelines or other services which may be affected by the heat. Particular attention should be taken when proposing to weld onto bulkheads or tank tops for temporary securing purposes. Familiarisation of the structure of the ship and the exact location of all fuel and ballast tanks is important in order that the aforementioned welding does not take place on fuel tank bulkheads. This is particularly relevant in respect of steel tank tops where there will inevitably be vapour on the lower side of the tank top. Cargo, fuel tanks, cargo holds or other tanks should be certified as gas free before any rep