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Fire Safety in Welding

Sparks and drips of hot molten metal can easily start a fire. Many people are injured each year by the incorrect and careless use of oxy/fuel gas equipment. The ‘blowpipe’ (the oxy/fuel gas torch) is a powerful source of ignition. The surrounding work area should be free of any ignitable materials such as wood, fabric, cardboard, rubber and plastics. Sparks and hot splatter can travel long distances and even ignite a fire at a far distance from the welding area or even in another room. Welding in enclosed spaces is particularly dangerous as smoke can build up and overcome people. Acetylene is commonly used for welding work. It is very explosive, even in small amounts and great care should be taken to ensure that the cylinder valve is turned off in transit. Explosions can occur when repairing tanks which contain flammable materials. Burns to the skin can occur through contact with hot metal or flames. During flame cutting, fumes are released which can cause asthma and other occupational diseases if one is not properly protected.

Simple precautions to prevent fire when welding include removing nearby combustible materials. If nearby combustible materials cannot be removed they should be protected with metal sheeting or fire retardant blankets. Openings under doors and windows should be covered so that flame particles cannot travel through them and hit nearby materials. Polystyrene is a flammable material so nearby wall cavities should be checked for this. Work in confined spaces, for example on a ship, may require a person to do a fire watch during the work process and 30mins after work completes. This is to ensure that not sparks have not hit areas that could later start a fire. Sparks should be prevented from landing on the hoses of the gas cylinders and fire extinguishers should be kept nearby.

Gas cylinders should be checked regularly for leaks (a suitable leak detecting spray or solution should be used). Fuel gases can form explosive mixtures with air and oxygen. All cylinders should be turned off when not in use and hoses should not be stored near sharp edges or near heat. Backfires may occur when the flame burns back into the torch and they are an indication of faulty equipment. To prevent flashbacks (flow of oxygen back into the hose) the hose should be purged before lighting the torch. The blowpipe should be fitted with non-return valves. Cylinders can be protected from flashbacks by using flashback arresters.

Toxic fumes can be emitted during the welding process. The worker may need respiratory protective equipment (RPE). If one is working outdoors RPE may not be needed, however, it must be ensured that the wind is not blowing the fumes into the path of the operator or other people. Oxygen should not be introduced around welding work as it can cause materials to be flammable. Oil and grease should be eliminated also, as these products can react explosively with oxygen. Obviously, in these situations, RPE is necessary for the operator. To avoid contact burns, it is preferable to clamp the work piece, rather than hold it by hand when holding the torch in the other hand. Because of the risks associated with this work, many companies operate a written permit system for welding work.

Sources   hse

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