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- Electrical Welding
- Autogenous Welding
- Risks and Prevention
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Electrical welding is performed by forming an electric arc between the electrode and the piece of metal to be welded.
Depending on the welding method used (manual, automatic, with electrodes, Mig, Tig etc) toxic fumes can be released during electric welding or arc welding, resulting from the smelting bath, the flux added in the electrode or protective gas.
Heat radiation, electrocution and strong UV radiation are additional risks.
Welding in closed spaces or humid environments is not only dangerous because of fumes; the risk of electrocution is real. An electric shock from a welding device can even have fatal consequences.
Damp skin, Caused by a humid environment and perspiration increases the risk of electrocution. It is also important for the welding transformer, the electrode holder and the cables to be well insulated.
Furthermore, the use of insulated gloves is required when placing or removing the electrode. The device must always be grounded so that the user can not receive electric shocks. In damp spaces, a power supply with lower safety voltage is generally used.
Fire and Explosion
During welding, sparks fly. When these sparks fall on flammable material, a fire can occur. Materials can catch fire not only because of the sparks themselves but also through the heat generated by welding. When explosive air-gas mixes are present in the work environment, there is also a danger of explosion.
Remove all flammable material and if necessary cover the ground with fire-resistant material. Wear a welding apron, so that your clothing can not catch fire. For all welding works outside the welding shop for instance in work yards, in other companies, a fire permit must always be requested from the client.
During electric welding, a strong UV light is emitted that can damage the skin and eyes. Short exposure to welding radiation can cause painful welding eyes. Long exposure can cause inflammation of the cornea can burn the skin around the eyes and blur the eye lens.
It is always mandatory to wear a welding mask. Special welding curtains can be used to screen off the UV light in order to protect bystanders from the light. Always wear the appropriate, close-fitting work clothing (gloves, apron and safety shoes) and eye protection.
Never weld with bare arms or legs, even when the weather is very warm.
Poisoning by Welding Smoke
Toxic fumes can be released during welding, which mixes with the surrounding air. These fumes are generated not only by the electrodes but can also originate from the welded metal itself. In a properly ventilated space, this is not usually a problem.
In addition to good ventilation an exhaust system that locally aspires the welding fumes at the source above the welding should be provided. Sometimes, it is necessary for the welder to wear a filtering mask or a breathing hood.
The protective coating (paint, zinc etc) on the surface to be welded must be removed. Oil, Grease and such must be removed before starting to weld.
During autogenous welding the heat that is necessary to meet the metal is generated by a mix of flammable gas and oxygen. A burner is used with a mix of oxygen and acetylene (or propane) to melt the two metals together. The gas is stored in gas bottles, which are connected to the welding device.
During autogenous welding pure oxygen is added. It is contained in oxygen bottles at a pressure of 200 bars. Combined with oil, fat or organic substances, oxygen can cause explosive fires. Avoid the use of organic fats or oils in the presence of oxygen bottles.
Acetylene is a colorless hydrocarbon gas with a garlic-like odor which is lighter than air. Acetylene forms a very explosive mix with air and oxygen. In order to avoid flash-back with autogenous welding devices, a flame damper is placed between the pipe and the pressure regulator.
An acetylene bottle must be stored upright. Propane is less dangerous than acetylene since it has a smaller flammability range. Propane is heavier than air; consequently, it hangs close to the ground.
Therefore, propane should never be stored in basements or pits. To avoid further release of gas, a hose breakage protection must be placed to immediately cut off the feed in case of hose breakage.
Risks and Prevention
In order to avoid gas release in case of brack or leakage of a feed hose, a hose break protection is placed to cut off the feed immediately. In order to avoid flash-back a flame damper is always placed to block the backfire of the flame to the bottle.
The radiation of the welding flame can cause an inflammation of the conjunctive and of the cornea of the eye. Welding glasses protect the eyes against radiation and against small glowing metal parts that could be projected.
Through a combination of high temperature and the ambient air, toxic fumes can be released. When degreasing or covering substances are present on metals, the risk is increased.
Good prevention rules are the following: the working area must be sufficiently ventilated, local exhaust must be provided and appropriate breathing protection should be worn.
Fire and Explosion
Autogenous welding always involves the perfection of sparks, hot metallic fragments and liquid metal drops. When they come in contact with flammable materials in the environment, they can cause a fire.
Make sure that there are no flammable materials near the welding site and always keep the necessary fire-fighting equipment at hand (fire extinguisher).