Vorkshop afety, 9
Page 49
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iE SAFETY precautions icessary in using oxyetylene welding equipment are considered in my previous tide. Many commercial bide workshops are equipped th electric arc welding luipment instead of, or as well , the "gas" type.
A face shield, with the rrectly tinted lens, must be ed with all types of arc The intense light produced by arc will injure the eyes, using the painful condition own as "arc eye", if this acaution is not taken. It is cessary for any helper, or rson nearby, to be similarly
Dtected.
The arc also produces
Nation in the form of ultra)let light which can burn the n, giving a similar effect as nburn, so welding gloves and 3ather apron should be worn. 'Splatter" and sparks coming m the welding operation uld cause injury to the welder d fire or explosion if the hot rticles come into contact with flammable substance. A tin DU Id be kept handy in which to ice scrap ends of electrodes. with any type of welding there in ever present risk of fire and )losion. Care must be taken to sure that nothing flammable 'ear enough to become
iited. In one case a mechanic, I police workshop, was Iding the sill beneath the door s car. He did not realise that re was a petrol pipe leading rri the tank to the engine ining along the inner side of sill. The car was a "write '. In another case, which identally resulted in a secution, a mechanic tried to weld a crack in an axle casing. The resulting explosion injured a workmate.
Dangerous fumes are generated by arc welding and also when certain metals are welded irrespective of the method used.
Particular danger from toxic fumes are present when flame or arc are applied to galvanised, zinc, lead or cadmium metals.
Many plastics produce toxic fumes when heated and some are flammable so all should be regarded as potentially dangerous and removed from the area of heat.
Many chemicals and fertilisers also produce harmful fumes when heated, so suitable precautions should be taken when these are present. Adequate ventilation is necessary when there is any risk of dangerous fumes and extra special precautions must be taken when the Welding has to take place in a confined space. If there is any doubt whether a particular job will be safe, seek specialist advice.
To avoid the risk of electric shock when arc welding, all cables must be in good condition and all joints properly made. The welding table, bench or workpiece must be properly earthed. Paint, rust or other coating must be removed before the weld return lead is attached to the workpiece by a properly constructed clamp or bolted terminal.
When welding on a motor vehicle the battery, generator and voltage control must be disconnected to prevent irreparable damage to the semiconductor devices and printed circuits likely to be found on modern vehicles.
It is possible for a second person working on a vehicle to receive an electric shock because of a fault in the earth return lead. In order to guard against this, the vehicle should be earthed through a separate lead of adequate capacity. Figure 1 shows how this should be done.
Tungsten Inert Gas (TIG) and Metal Inert Gas (MIG) welding equipment are used in some electrical welding processes and the same precautions need to be taken as when ordinary arc welding is being carried out. It is important that adequate ventilation is provided with either of these processes.
The repair of drums and small tanks creates such an explosion and fire risk that the Health and Safety Executive has produced a special booklet dealing with this subject. It is pointed out in the booklet that half a fluid ounce of liquid in a 200 litres (40 gal) drum can give sufficient vapour to form an explosive atmosphere and that this amount of liquid can easily be trapped in a seam or be present in a very thin film on the inner surface of the vessel.
Fairly recently a case was reported where an air receiver exploded while it was being welded; presumably this was caused by oil, which had come from the air compressor, being ignited.
Tanks should be steamed out or completely immersed in boiling water containing an effective alkaline degreasing agent or detergent before any soldering or welding work is done. Once again, specialist advice should be sought if there is any doubt whether it is safe to weld a particular job.