Part 1: Welding hazards

Fires and Explosions

These are an ever-present hazard with many welding processes.

Burns

Welding causes items to become hot - creating a risk of burns and fires from hot metal and welding spatter.

Fumes

Fumes generated by different welding processes may range from being of nuisance value to highly toxic. Health effects can occur very soon after exposure (e.g. exposure to cadmium fumes can be fatal within hours) or may not result until after many years. Fume control requires appropriate ventilation equipment and may require advice from a specialist.

Electric Shock

Welding processes that use electricity pose both obvious and subtle hazards of electric shock - which can be fatal. Standard precautions, as explained in this book, need to be taken during the use of welding equipment, and expert assistance can be needed in some circumstances to identify subtle hazards. Equipment selection, set-up and maintenance is important and may require specialist advice to ensure safety.

Compressed Gases

Compressed gases in cylinders pose a number of hazards. Methods for their safe use are outlined in TN7 chapter 5.

Hazardous Substances

Hazardous substances used during some welding processes can require highly specialised methods of control (e.g. the extremely toxic hydrofluoric acid.)

Toxic Gases

Toxic gases may be:

• used in, or generated by, the process (e.g. acetylene, ozone, nitrogen oxides, carbon monoxide)
• generated when coatings on metal surfaces are heated (e.g. epoxy resins, degreasing agents, paint)
• generated when the arc flash and some degreasing chemicals or paints react (e.g. phosgene or phosphine).

Precautions for preventing these hazards from causing harm are outlined in TN7 chapters 5 and 10.

Suffocation

Inert gases used during welding can flood an area and lower its oxygen content, especially in confined spaces. Suffocation can result.

Radiation

Arc flash is a well known hazard of welding. Standard precautions (see part 15) should be used to prevent eye and skin exposure - both for the worker and for people in the vicinity. Reflecting surfaces make exposure to radiation more likely.

Heat Stress

Working for long periods in hot environments can lead to distress and in an extreme, fatal heat stroke. Specialist advice must be sought if welders work in hot environments. (See TN7 chapter 23.)

Dust

Associated processes (grinding) may generate hazardous levels of dust.

Noise and Vibration

Noise and vibration levels during some welding processes can be high and should be controlled and/or appropriate hearing protection should be worn.

Manual Handling

Some welding processes may involve heavy and or repetitive handling.

Specific Processes

Several processes, not covered by this booklet, are discussed in TN7:

• thermit welding
• laser welding
• electroslag welding
• plasma cutting
• resistance welding
• electron beam welding
• brazing and soldering
• thermal lancing.

Part 2: Training, Qualifications and Competency

General

Welding involves a wide range of processes carried out in a variety of working conditions.

Certain work, especially where safety critical items are fabricated, requires a high level of skill and competency (e.g. welding pressure vessels) whereas a high skill level may not be so critical in some general purpose welding.

Only workers with appropriate levels of competence and skill should do welding. They must know:

• the right way to do the work
• the hazards of the work
• how to prevent those hazards causing harm.

Competence in welding may be shown by an appropriate qualification issued by a registered training organisation (such as an industry training organisation (ITO)) or relevant unit standards for welding from the National Qualifications Framework. Welders should not use equipment for which they are not certified.

Welders should be trained in the use of fire extinguishers and hot work permits, if they are used.

The Value of Experience

Welding is often a complex, safety critical operation and a great deal of knowledge may be required to provide for all aspects of health and safety.
This knowledge will not come entirely by reading or training. Experience, skill and practice should also inform safe working practices.

This means that welding safety should be considered a team effort, with team leaders actively coaching team members and team members referring to knowledgable team members if they are not sure of correct health and safety practices. This is especially important when doing new tasks.

Relevant Standards

Standards applying to welding processes include:

• NZS 4711: 1984. Qualification tests for metal-arc welders.
• AS/NZS 1338.1:1992 Filters for eye protectors-Filters for protection against radiation generated in welding and allied operations
• The AS/NZS 1554 series. Covers: Welding of steel structures; Welding of high strength quenched and tempered steels; Welding of steel structures to high levels of fatigue loading; Welding stainless steel for structural purposes
• AS 1796-Certification of welders and welding supervisors
• AS 2214-Certification of welding supervisors - structural steel welding.
• AS/NZS 3100:2002 Approval and test specification - General requirements for electrical equipment
• AS/NZS 3195:2002 Approval and test specification - Portable machines for electric arc welding and allied processes
• AS/NZS 1995:2003 Welding cables
• AS/NZS 3957:2006 Light-transmitting screens and curtains for welding operations.

The New Zealand Qualifications Authority (NZQA) publish a list of over 30 unit standards for welding processes. This includes US 21907 Demonstrate and apply knowledge of safe welding procedures under supervision, and there are also health and safety components in each of the unit standards listed. See the New Zealand Qualifications Authority website .

Part 3: Equipment Selection, Maintenance and Safety

Consult TN7 for details of selecting the right equipment for the particular welding process being carried out.

Generally, the manufacturer or supplier of the equipment will give detailed directions for setting up the equipment, safe usage and maintenance. These directions should be followed.

Part 4: General Health and Safety in Welding

Good Housekeeping

Good housekeeping, especially the removal of combustible materials, is essential.

Gas

If you can smell gas - don't light any gas torches or use electric welding equipment, but don't rely wholly on your sense of smell to warn you.

Eye Protection

Wear eye protection and cover bare skin. Be aware that:

• arc flash can occur through the side of the eye
• arc flash can cause 'sunburn' on exposed skin.

Hot Surfaces

Mark hot surfaces as such. Better still, assume everything is hot.

First Aid

In addition to standard training, first-aiders in welding situations should know about the symptoms of electric shock, arc flash and the consequences of exposure to heated coatings on metals (e.g. when galvanised metal is welded).

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