TIG Welding Machine. Introduction Risks & Hazards General Safety Operating Safety Maintenance Operating Procedures

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1 TIG Welding Machine This is a RESTRICTED item in NSW DET schools, where TEACHER USE ONLY is permitted. In VIC DEECD schools, this item can only be used by students under general supervision after the student has passed a Safe Use Competency test Introduction Risks & Hazards General Safety Operating Safety Maintenance Operating Procedures Introduction The information contained in this SOP is general in nature. It is advised that operators are referred to the relevant manufacturer's manual for specific operating information. TIG Welding can be used to weld aluminium, copper, titanium etc and even two dissimilar metals. This process is ideally suited to handling tricky welds such as S-Shapes, curves, corners or where the weld is going to be visible and where accuracy and finish is important. TIG stands for Tungsten Inert Gas named from the tungsten electrode and the shield of inert gas (Argon or argon mixture) surrounding it. TIG welding allows a greater variety of metals to be welded than other forms of welding. With superior arc and weld puddle control, TIG welding allows you to create clean welds when appearances count. Because the heat input is often controlled by pressing on a foot pedal, similar to driving a car, TIG welding allows you to heat up or cool down the weld puddle giving you precise weld bead control. This makes TIG welding ideal for cosmetic welds like sculptures, architectural and automotive welds. The TIG welder generates heat via an arc of electricity jumping from a tungsten metal electrode to the metal surface that you intend to weld which is usually aluminium or steel. A TIG welder needs a filler rod to provide the welding bead when joining two pieces of metal together. TIG welding produces no sparks or spatter because only the necessary amount of filler metal is added to the welding pool. TIG welding produces no smoke and fumes unless the base metal contains contaminants or has a dirty surface. TIG welding doesn t produce slag and requires no flux because the argon gas protects the weld pool from contamination. Identified Risks and Hazards Hazards that may arise when electric arc welding include: burns from hot metal burns from ultraviolet and infra-red rays electric shock from faulty electrical equipment inhalation of noxious welding fumes welding slag being propelled into the eyes or onto the skin

2 Specific hazards that may arise when TIG welding include: Bystanders can be at risk if near welding. Welding creates a flash hazardous to unprotected bystanders. The high temperatures created by a TIG welder can cause fire. Extremely high temperature of the heated material and the sparks created by the arc can burn operators. Toxic fumes created by welded metals are a major hazard. Metals such as nickel and chromium found in steel, tin, copper and have hazardous coatings. DO NOT WELD GALVANIZED STEEL. Galvanized steel contains a zinc coating that produces carcinogenic and poisonous gas when it is burned. Exposure to the stuff can result in heavy metal poisoning (welding shivers) - flu like symptoms that can persist for a few days, but that can also cause permanent damage. Welding in confined spaces can create build-up of toxic fumes. The flash created by TIG welding is extremely hazardous to eyes. Pre-operational Safety Always obtain permission from the supervisor before using the welder. Never operate welding machines in wet or damp conditions. Switch off and remove the plug from the power outlet before fitting attachments or making adjustments. Never connect a welder to a damaged power outlet. Fasten any loose clothing and tie apron cords or straps at the back Remove any jacket or coat and any school uniform tie Roll up shirt sleeves above the elbows or fasten them securely at the wrists Do not wear finger rings, watches, bracelets or necklaces Wear solid firm shoes which provide adequate protection for the feet Wear appropriate Personal Protective Equipment such as long leather gauntlets, leather apron, leather spats and leather shoes/boots. Wear appropriate PPE such as a respirator if the welding operation produces fumes which could be a respiratory hazard. Fumes from welding brass, bronze, galvanised iron, cadmium, zinc and lead are all quite dangerous. Long hair must be contained with a suitable cap or net. Contact lenses should NOT be worn while welding or when working around welders or in a dusty environment. The eyes must be shielded before striking an arc. Be vary careful not to cause an accidental 'flash'. Hearing protection such as ear muffs must be worn as noise levels are identified as hazardous.

3 Never attempt to weld any petrol tank or container which has held a flammable substance. Operating Safety Precautions Before using the welder, examine the power cord, extension lead, plugs, sockets and power outlet for damage. Look for: cracked or damaged casing bare wires or loose connections damage to cord sheathing loose or missing screws Before starting the welder ensure that the handpiece is in good order. Check for excessive charring at the end, cracked or damaged parts, exposed metal parts or poor cable connections. The welder must have all covers in place and must be located in a dry place. Terminals, washers and knobs must be in good condition for a firm connection. Secure and support the workpiece using clamps, bench vices or appropriate weights. Ensure that there are no flammable gases, liquids or other materials in the welding vicinity. Make sure the floor area is not contaminated with oil or grease. Where a ventilation system is available, make sure it is operating properly. Do not weld in confined spaces, or where the ventilation is considered not to be adequate. Daily Maintenance On completion of the welding procedure, clean down the welding machine and return it to its storage position. Look for cracked or damaged casing, bare wires, loose connections, damage to cord sheathing, loose or missing screws, or blocked ventilation slots. Never use a defective welding machine. Report it to the supervisor. Isolating and Lockout Switches Electrically operated machines should be fitted with a flush green on or start switch and a red stop switch that has a raised mushroom shaped head for

4 fast emergency contact. As well as start and stop switches, all machines must have an isolating switch, which enables the main power supply to be switched off when the machine is being set up, adjusted or when maintenance is being carried out. Operating Procedures Seek and gain teacher approval to carry on with the welding procedure. Ensure the supervisor is in the immediate work area and can supervise the welding procedure. A tungsten electrode is required when TIG welding and this is inserted into the welding torch. This electrode carries the welding current to the work. There are different sizes of tungsten s available which relate to the welding power you are using for a particular job. It is important to use the correct size of electrode for the welding power you are going to use. Preparation of the tungsten electrode is important. The end needs to be ground to a point. Brand new electrodes will always need to be prepared in this way. When welding on aluminium the tungsten will begin to form a ball, this is perfectly normal. When welding steel the electrode will always stay pointed. Make sure all other persons keep outside the welding zone at all times. Operate the welding machine in a welding booth or behind a protective welding screen. Make sure the welding area is well ventilated, and be aware at all times of any obvious and/or dangerous fume build up. Make sure there are no water puddles or pools anywhere near the welding area. A hand shield or helmet with the correct shade filter must be used by the operator, assistant, instructor and observers. Clean the metal thoroughly before welding. Fumes from heated paint, oil, grease or other chemicals may be a health and/or fire hazard. Keep the welding leads clear of the work and protect them against damage from hot, sharp or heavy contact. Make sure the earth clamp is tightly fixed to clean metal on the workpiece or the welding table. When not in use the handpiece should be placed in a safe insulated position. The main power switch must be turned off when changing welding leads and when leaving the welding area.

5 Switch off the welder at the power outlet and remove the plug when it is not in use. Never use a defective welding machine. Report it to the supervisor. Handle hot materials with care. Regard all metal workpieces in the welding area as being hot. The questions in the SOP knowledge test are general in nature. The manufacturer's manual is to be used to develop specific questions relevant to this tool or machine.