TIG welding

TIG WeldingThere are many different types of safety hazard produced by TIG welding. The main risks are from electric shock, welding fume and radiation. Hazards may be present before, during or after welding.

The TIG process produces a variety of hazards, not only to those carrying out the operation but also in many instances to others in the vicinity such as inspectors, labourers and even other welders. Some of the hazards encountered are specific to TIG welding while others are of a more general nature.

Different hazards occur before welding commences, during welding and sometimes after welding has finished.

All the potential hazards need to be identified, measured where appropriate, assessed, and remedial or preventative measures put in place wherever necessary. It should also be remembered that different hazards may have the same effect on the body and so interactions between hazards should also be considered.

Types of Hazards in TIG Welding

The hazards encountered in TIG welding may be sub-divided into groups as follows:

  • Electrical and magnetic fields
  • Compressed and inert gases
  • Radiation
Electrical Safety & Magnetic Fields

Power sources for TIG welding and associated pieces of equipment, such as 'add-on' units, welding torches, leads and connectors all require electricity to operate. Power sources may be AC/DC or DC, operate from a three-phase supply, from industrial single-phase supply or even from a 13amp domestic power supply, and may be designed to operate with a high open circuit voltage (OCV).

Primary and secondary connections should be completed by competent persons.

It should always be remembered that electric shock can kill.

Due to the potential severity of the hazard, the following is a guide on what to do before any TIG welding is started to reduce the risk of an electrical accident:

- Only qualified personnel should be allowed to install TIG equipment.

- The equipment must be tested to ensure it is operating correctly and safely before being put into service.

During welding the possibility of electric shock is one of the most serious risks encountered by a welder.

The following point provides a guide on what to do to reduce the risks:

- Welders should not remove panels from a welding power source if it stops working correctly. Touching a lead inside the welding set with the power still on can result in a serious primary voltage shock.

The following practice will help prevent electrical accidents:

- When welding is temporarily interrupted welding torches should be placed where they are safe and the switch cannot be activated accidentally.
Compressed and Inert Gases

Shielding gases for TIG welding are in terms of health and safety, to all intents and purposes, inert.

Inert gases are not toxic, but will not support life.

Of the two main inert gases used in TIG welding helium is lighter than air but argon is heavier and can gather in low lying areas if the atmosphere is still and relatively undisturbed.

Radiation

Arc welding produces electromagnetic radiation over a wide range of wavelengths. These wavelengths cover three distinct types of 'non-ionizing' radiation, namely, Ultraviolet (UV), Visible Light and Infrared (IR). TIG welding does not produce ionizing radiation.

Burns to the skin and eyes due to exposure to arc radiation may not become apparent until some time after welding has ceased.

Some points to bear in mind are:

- Radiation is only generated while the arc is generated and the amount emitted generally increases as the welding current increases.

- Burns can be avoided by wearing proper protective clothing and ensuring no areas of skin are left exposed.

Heat

Sources of heat include welded components, the electrode holder and hot or discarded electrodes, and any of these can cause burns to the skin.

A hot environment can cause the body to overheat, and this is known as Heat Stress.

However those working in welding shops can reduce the risk by adhering to the following recommendation:

Always assume all metal objects in a welding shop are hot.

Welding Fume and Gases

Welding fume is an unavoidable by-product of TIG welding, although fume generation from the process is generally low. However, the welder should still be aware of what fume is likely to be generated while welding is taking place and the potential hazards of exposure to the welding fume.

Particulate Fume

Particulate fume is mostly formed from vapourisation of the welding consumable in processes where the consumable is transferred across an electric arc.

Gaseous Fume

Welding processes with open arcs, such as TIG, are likely to promote the formation of gaseous fume as a result of the action of ultraviolet light and heat on atmospheric oxygen and nitrogen.

Exposure to Fume

Whilst all components of welding fume may present a risk to health, given a high enough concentration, some present a greater hazard than do others. The potential effect of exposure to welding fume depends upon:

- The composition of the fume.

- The volume of fume produced.

Noise
The TIG welding processes, like all others, generates noise, although it tends to be the quietest of the major arc welding processes.
Manual Handling

Back injuries are one of the most common industrial injuries suffered by workers. When moving and positioning welding equipment, be aware that these units are often heavy, including some of the so-called 'portable' units.

- Tubes of TIG filler rods stored high off the ground can create a 'falling' hazard.
Confined Spaces
Any of the hazards associated with TIG welding will be exacerbated when welding is carried out in a confined space. When TIG welding in a confined space, there is also the potential additional hazard of a build-up of inert shielding gas to contend with.
Thoriated Electrodes
Thorium is a radioactive alpha emitter, which means that it is a hazard if inhaled or swallowed. Some tungsten electrodes used in TIG welding are alloyed with thorium oxide, thoria, to improve arc striking and stability.
Solvents

Flammable solvents may have been used to clean components prior to welding and may still be present around the welding area, presenting a fire or explosion hazard. Similarly chlorinated hydrocarbon degreasers, such as 1-1-1 Trichloro-ethane (Genklene), may have been used.

The welder should allow all traces of any solvents to disappear from component surfaces and ensure no containers of solvent are in close proximity before welding starts.

Workshop Safety

General workshop safety is really a matter of common sense and good housekeeping and the following actions may be used to avoid accidents:

- Maintain a tidy work area, especially free from trip hazards.
- Keep walkways clear and free from welding cables, spare material, consumables, etc.
Practical Considerations

The advice given above is general in nature but forms a good overview of the potential hazards associated with the process. There are, however, things that can be done to help reduce the possibility of problems occurring in the workplace:

Training

There is a considerable amount of misinformation in the fabrication industry about the health hazards associated with welding. There is also a lack of understanding among welders as the how they can influence the type and severity of hazard. The main cause for this is often poor training and some welders appear to be unwilling to operate at welding conditions that will keep fume production to a minimum.

Routine Maintenance, Safety Audit and Equipment Inspections

Simple routine maintenance and a formalised system of safety audits on welding equipment has been shown to help reduce the number of safety related incidents within the industry.

Personal Protective Equipment

Welders should ensure that they wear appropriate clothing for the operation they are carrying out. Flame-retardant boiler suits, gloves or gauntlets, safety shoes, leather aprons, etc, should be in good condition and as free from oil, grease and moisture as is physically possible as these can reduce the effectiveness of the safety equipment.