Risks of Welding
Welding jobs are carried out in many workplaces. The risks involve not only the welder doing the job but also those who are working nearby.
Welding fumes are the most serious problem in all types of electric welding. The fumes contain a number of hazardous substances. Use local suction exhaust when working indoors, particularly in enclosed areas. The exhaust system must be placed as close to the point of the weld as possible. Screen off the work area to protect other people from welding glare. Earth the workpiece well, and if possible, place it at a comfortable working height, for example in a jig on a welding table. All paint, plastic and other pollutants must be cleaned off the work piece. This is particularly important when gas welding.
The risks include eye damage, skin injuries, burns and inhalation of toxic gases. For all the welding jobs, the welder should wear suitable protective goggles or a face mask to protect his eyes against the welding arc. This applies even to the job of scraping off slag. The work area should be partitioned off so that people nearby are not exposed to the arc. The welder should also wear protective gloves. Apart from the intensive glare, which is typical for all types of welding, we must note that in electric-arc welding the light-arc radiates invisible ultraviolet and infra-red rays. These are dangerous and can damage the eyes and the skin. In such cases the eyes should be protected with a special type of filter glass.
Use a helmet and gloves , to protect carefully the face and hands. In electric-arc welding, there are also the added risks injury by electricity.
Some types of welding require effective air extraction from the work area. This is important when the welding is carried out on metals covered with an alloy of lead, cadmium, mercury, flourine or zinc. Welding on such alloys leads to a build up of dangerous fumes and gases.
Gas welding in a confined space, especially when heating or straightening, can cause an accumulation of nitric gases, containing dangerous nitric oxides. In cases where effective local ventilation cannot he arranged, the welder should be provided with respiratory protection and a supply of fresh air. Always think about the safety of people working nearby and how they too can be exposed to dangerous fumes or gases.
Risk of welding fire
If you are welding in different places you can use a smoke exhaust (smoke eater). It prevents the airborne dust particles in the welding air to be spread out into the work place. Welding in or near a room where flammable material is stored should never be allowed. Even more importantly, welding should not take place in a tank, container or similar apparatus which is used for storing flammable liquids, until the risks for fire or explosion have been removed. The tank (or container) must be thoroughly cleaned, preferably using pressurised steam, before any welding is carried out.
Pumping air into the tank or to fill it with water up to the level at which the welding job is to be carried out will also serve as a good safety measures. “Welding bugs” are the biggest single cause of fires in connection with welding. A shower of sparks can cause a fire several meters away from the work area. This is often the case when the welding job is carried out at elevated levels. Experience has shown that burning particles can fly 20 meters through the air and cause a fire.
Acetylene and oxygen are normally used in gas welding. The oxygen and acetylene hoses should be easily distinguished and gas cylinders should be stored in a safe place. In the event of a fire it should be easy to remove the cylinders to a safe place. The gas hoses should be carefully protected against heat, sharp objects and dirt, especially oil and grease. These substances can even in small amounts cause an explosive ignition in the event of a leak in the oxygen hose.
Pressure vessels and Boilers
Pressure vessels and boilers need particular precautions. Especially stringent regulations apply to them. They entail risks of explosions or accidents due to component failures. The high internal pressure and frequent pressure changes give rise to these risks. It is essential to make sure that boilers and pressure vessels are installed and operated according to regulations and maintained by qualified persons. They must be inspected at regular intervals by authorised, competent persons belonging to a state authority or to a recognised technical association.