WELDING SAFETY

The major health hazards in welding and cutting are:

fumes
gases
radiation
noise
various safety factors
manual handling problems

The variables that influence exposure to these hazards include:
variables in the welding process
effect of the work area
effect of the operator

Fumes are fine, solid particles, formed by the following general process:
1. Metal and flux undergo rapid melting accompanied by limited vapourisation
2. Vapours are oxidised
3. Reaction takes place with flux constituents and other materials present
4. Vapours condense and agglomerate to produce fine particles of fume of complex composition.

Gases may be produced in certain welding processes in the following ways:
1. Decomposition of flux or electrode coatings and base metal coatings such as paints and solvents.
2. Reaction products of the shielding gases.
3. Oxidation of elements present in the arc or flame.
4. Photochemical reaction of atmospheric gases due to ultraviolet radiation from the arc or flame.

The electrode coating is a complex mixture of various components such as:
1. Moulding Agents (aluminium and magnesium silicate)
2 Extruding Agents (alginates, starch, glucose and methyl cellulose)
3. Binders (potassium and sodium silicates)
4. Strengthening Agents (mostly mica which has replaced asbestos)
5. Slag Formers (carbonates, silicates, oxides-rutile (TiO₂) and fluorides)
6. Metal Powders (e.g., iron) to act as alloying additions, to increase deposition rate or act as deoxidants
7. Shielding Gas Formers (cellulose, calcium carbonate)
8. Fluxing Agents (fluorspar, calcium carbonate and sodium silicate)

[Detail]

Reference : Welding Technology Institute of Australia, Health and Safety in Welding