Valahia University

Health Hazards of Welding

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At present, it is estimated that more than one million workers are employed as welders worldwide (Sundin, 1998), with more than three million performing welding intermittently as part of their work duties (Sferlazza and Beckett, 1991). Manual metal arc welding (MMAW) and flux core arc welding (FCAW) are two commonly used procedures in the construction industry and in numerous other industrial processes. Welding involves the fusion of metals by high temperature generated via an electrical arc resulting in the formation of metal-enriched fumes.

There are more than 80 different types of welding and associated processes. Some of the most common types of welding include: arc welding, which includes 'stick', or shielded metal arc welding (SMAW), the gas-shielded methods of metal inert gas (MIG) and tungsten inert gas (TIG), plasma arc welding (PAW), and submerged arc welding (SAW). Other welding processes may use oxy-acetylene gas, electrical current, lasers, electron beams, friction, ultrasonic sound, chemical reactions, heat from fuel gas, and robots.

The main electric arc methods which are employed for welding stainless steels are:
-Gas Tungsten Arc Welding (GTAW)
-Plasma Arc Welding (PAW)
-Gas Metal Arc Welding (GMAW)
-Flux-Cored Arc Welding (FCAW)
-Shielded Metal Arc Welding (SMAW)
-Submerged Arc Welding (SAW)

These factors are interdependent and generally have a substantial effect on the generation of fumes.
• Electric Arc Processes for Welding of Stainless Steel
prepared by Pierre-Jean Cunat, Technical Director, Euro Inox)

Welding Gases and Fumes
Welding fumes are a complex mixture of gases and small particulates of metal oxides formed by the vaporization and oxidation of metal during the welding process (Lockey et al., 1988, Yu et al., 2000). The nature of respirable fumes depends upon the type of welding and the composition of electrode, filler wire, and fluxes (Antonini et al., 1996, Lockey et al., 1988, Sferlazza and Beckett, 1991, Yu et al., 2000).

Welding fume is a mixture of airborne fine particles. Toxic gases may also be generated during welding and cutting.

More than 90% of the fume arises from vaporisation of the consumable electrode, wire or rod as material is transferred across the arc or flame. The range of welding fume particle size is shown in relation to more familiar types of dust and fume. The respirable fraction of particles (especially less than 3µm) are potentially more harmful as they can penetrate to the innermost parts of the lung.

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