Metal Inert Gas (MIG) welding is a versatile and widely used welding process in Kenya's manufacturing, construction, and repair industries. Mastery of MIG welding operations requires not only technical skill but also strict adherence to occupational health and safety standards to protect welders and ensure quality workmanship. This chapter focuses on the essential safety practices, legislative frameworks, and workplace procedures that govern MIG welding environments. Understanding these aspects is critical for welding professionals working in diverse settings such as fabrication workshops, automotive repair shops, and industrial plants across Kenya.

1.1 Occupational health and safety standards

Metal inert gas (MIG) welding is a clean and productive process, but it carries the hazards of all arc welding and some of its own. The arc gives off intense ultraviolet and infrared light, the work and the spatter are hot enough to burn, the machine runs on mains electricity, welding fumes and gases are produced, and the process depends on compressed gas cylinders under high pressure. A workshop that welds safely has fewer injuries, fewer stoppages and lower repair costs, and its welders stay healthy for the whole of their working lives.

Occupational health and safety is the combination of laws, standards, procedures and good habits that protect people at work. This topic covers the law and the standards, how hazards are found and their risks judged, the reporting of accidents, ergonomics, waste and the environment, the safety rules and equipment of the workshop, the procedures that staff follow, the hazards specific to welding, and housekeeping.

1.1.1 Workplace legislation and standards

The main law on safety at work in Kenya is the Occupational Safety and Health Act, 2007. It places duties on the occupier of a workplace to provide a safe place and system of work, to give workers information, instruction, training and supervision, to provide protective equipment and to look after workers' welfare. Workers have duties as well: they must take reasonable care of their own safety and that of others, follow the safety rules, use the protective equipment they are given and report hazards and accidents.

The Directorate of Occupational Safety and Health Services (DOSHS) enforces the Act. Its inspectors visit workplaces, advise the occupier and can order improvements, stop unsafe work and take offenders to court. A workshop that ignores the law risks injuries and compensation claims, stoppages, fines and loss of reputation.

Other laws and standards apply to a welding workshop:

• Work Injury Benefits Act, 2007: provides for compensation to workers who are injured or become ill because of their work.
• Environmental Management and Co-ordination Act, 1999: protects the environment, and the National Environment Management Authority (NEMA) enforces it. It covers pollution from smoke and fumes, and the disposal of waste.
• Standards: the Kenya Bureau of Standards (KEBS) publishes standards for products sold in Kenya, including protective equipment and welding consumables. International standards for welding and for gas cylinders are also used, and a workshop follows the standard named in the job specification or the maker's instructions.

1.1.2 Workplace hazard identification

A hazard is anything with the potential to cause harm, and hazard identification is the systematic search for hazards before they hurt anyone. In a MIG workshop the main hazards are the arc light, heat and spatter, electric shock, fumes and gases, noise, cylinders under pressure, sharp metal, heavy lifting and fire.

Hazards come from several sources: the process (arc, current, gas), the equipment (damaged cables, worn regulators, unguarded grinders), the materials (coated or galvanised steel, solvents, paint), the environment (poor ventilation, wet floors, poor lighting) and the people (fatigue, lack of training, rushing).

Methods of finding hazards:

• Workplace inspections: regular walk-rounds with a checklist.
• Job safety analysis: breaking a job into steps and looking for the hazard at each step.
• Worker reports: workers who do the job every day know its dangers, so a simple way of reporting them is important.
• Review of accidents and near misses: past events show where a workshop is weak.
• Maker's information: manuals and safety data sheets name the hazards of machines and materials.

Safety signs and labels warn people of hazards at the place where they occur: red for prohibition and fire equipment, yellow for warning, blue for a required action and green for safe conditions. Workers who are involved in finding hazards take more care and tend to keep the rules.

1.1.3 Risk Assessment

A risk is the chance that a hazard will cause harm, combined with how serious that harm would be. Risk assessment is the process of judging each hazard so that the most serious are dealt with first, and the resources of the workshop are spent where they are most needed.

Steps in a risk assessment:

1. Identify the hazards of the job.
2. Decide who could be harmed and how, including visitors and trainees.
3. Rate the likelihood of harm and the severity of harm.
4. Decide on controls to remove or reduce the risk.
5. Record the findings and tell the people concerned.
6. Review the assessment regularly, and after any accident or change in the work.

A simple risk matrix scores likelihood from 1 (rare) to 5 (almost certain) and severity from 1 (minor) to 5 (fatal), and the risk is the product of the two. Example: welding without a screen near another worker has a likelihood of 4, and the harm of arc eye is a severity of 3, so the risk is 4 × 3 = 12, which is medium to high and needs action. Fitting a welding screen reduces the likelihood to 1, so the risk is 1 × 3 = 3, which is low.

Controls are chosen by working down the hierarchy of controls:

1. Elimination: remove the hazard, for example by buying pre-cleaned steel so that no grinding is needed.
2. Substitution: replace the hazard with a safer one, for example a water-based cleaner in place of a solvent.
3. Engineering controls: guards, screens, fume extraction and earthing of equipment.
4. Administrative controls: training, procedures, signs and limits on the time of exposure.
5. Personal protective equipment: the last line of defence, used when the risk remains.

1.1.4 Workshop Incident/Accident reporting

An accident is an unplanned event that causes injury or damage, and a near miss is an event that could have caused harm but did not. Both are reported, because every near miss is a warning that an accident could follow.

Reportable events include injuries, burns and arc eye, electric shocks, fires, gas leaks, damage to equipment, dangerous occurrences and cases of work-related illness. The law requires serious accidents and certain dangerous occurrences to be reported to DOSHS.

A reporting procedure follows these steps:

1. Give first aid and make the area safe.
2. Tell the supervisor at once.
3. Complete the accident report form, with the date, time, place, persons involved, what happened and the injury.
4. Investigate the cause by looking at the site, the equipment and the procedure, and by asking those present.
5. Take corrective action to remove the cause, and record it.
6. Review the records to look for patterns, and share what is learned.

The purpose of the investigation is to find the cause and prevent a repeat, and not to blame a person. Workers who report an event in good faith are supported, and details of an injured worker are kept private.

1.1.5 Workplace ergonomics and work design

Ergonomics is the fitting of the work, the tools and the workplace to the person, so that the work is done in comfort and without injury. Poor ergonomics is a common cause of back, neck, shoulder and wrist injuries in welders, because the work often involves awkward postures held for a long time.

Common ergonomic risks in MIG welding are bending and twisting at a low bench, lifting heavy plate and cylinders, holding a heavy torch and cable in one position, working with the arms raised, and a tense grip on the torch for long periods.

Good work design includes the following:

• Workbench height: set so that the welder works with the elbows bent at about a right angle and the back straight, with adjustable tables and sitting stools where the work allows.
• Positioners and clamps: hold the work so that the welder does not have to hold it in a strained position.
• Lifting aids: trolleys, hoists and cylinder trolleys in place of lifting by hand, and two people for heavy items.
• Cable support: hang the torch cable from a boom or hook so that its weight is not carried by the wrist.
• Breaks and rotation: short breaks and a change of task to rest the muscles, particularly in hot conditions.
• Training: workers are taught to lift correctly, with the load close to the body and the legs doing the work.

1.1.6 Workshop waste management

A MIG welding workshop produces waste every day, and managing it prevents injuries, fires and pollution. The aim is to reduce the amount made, to reuse and recycle what can be, and to dispose safely of the rest.

Types of waste in the workshop:

• Metal offcuts and scrap: valuable, and sold for recycling or reused for small parts.
• Spent wire, wire spool cores and packaging: collected for recycling or disposal.
• Spatter, slag and grinding dust: collected in covered containers.
• Used contact tips, nozzles and liners: worn consumables that are collected as scrap metal.
• Oils, solvents, paints and cleaning chemicals: hazardous waste that is kept in labelled, sealed containers.
• Empty and faulty gas cylinders: returned to the supplier.
• Used filters from fume extractors: collected and disposed of as the maker advises.

Waste is separated into marked containers, with each type kept apart from the others, and hazardous waste is stored safely until it is collected. Burning waste and pouring it into drains is not allowed. The Environmental Management and Co-ordination Act, 1999 and its regulations govern the handling and disposal of waste, so waste carriers and disposal sites must be licensed by the environmental authority.

1.1.7 Workplace environmental safety

Environmental safety deals with the effect of the workplace on the people in it, and on the surroundings, through the air, noise, chemicals and spills.

• Air quality: welding fumes and gases are controlled by extraction at the source, by good general ventilation and by respirators where these are not enough. Extraction is placed near the arc and the fumes are drawn away from the welder's face.
• Noise: grinding, chipping and hammering are loud, and noise is reduced by choosing quieter methods, by enclosing machines and by ear protection.
• Storage of gases and chemicals: cylinders are stored upright, secured and in a ventilated place, away from heat, and chemicals are kept in labelled containers in a cupboard with a spill tray.
• Spills: oil and coolant spills are cleaned at once with absorbent material, and the used material is disposed of as hazardous waste.
• Protecting the community: smoke and fumes are not allowed to drift towards neighbouring homes and shops, and noisy work is done at sensible hours.

1.1.8 Workshop safety

Workshop safety is the daily practice that keeps the workshop a safe place to work. It rests on the rules of the workshop, the protective equipment worn by the people in it, and the way the workshop is arranged.

1.1.8.1 Regulations

Workshop regulations are the written rules for working in the workshop, based on the law and on the instructions of the makers. They are displayed and explained to every new worker, and they are enforced by the supervisor.

• Authorisation: only trained persons who are authorised may operate the welding machine.
• Inspection before use: check the machine, cables, torch, regulator and hoses before every job.
• Protective equipment: the equipment is worn for every task for which it is required.
• Cylinders: cylinders are kept upright and secured, and are moved on a trolley with the valve cap on.
• Hot work: flammable materials are cleared from the area, and a fire extinguisher is placed close by.
• Electrical safety: the work piece is earthed, and damaged cables are taken out of use.
• Conduct: no running, no horseplay and no eating or drinking in the welding area.

1.1.8.2 Personal Protective Equipment

Personal protective equipment (PPE) is worn by the person to reduce injury when the hazard cannot be removed by other means. It must be of the correct type, fit well, be kept in good order and be replaced when damaged.

1.1.8.3 Layout

The layout of the workshop affects safety. A good layout keeps hazards apart, gives clear escape routes and makes work flow in one direction.

• Welding bays: each bay has a screen or curtain of welding grade to stop arc light reaching other people, and the walls near the arc are not painted a bright colour that reflects the light.
• Ventilation and extraction: extraction points are placed at the welding positions, and the air is able to move through the workshop.
• Separation: grinding, welding, storage of materials and gas cylinders are in separate areas, and flammable materials are kept well away from the welding.
• Walkways and exits: gangways are kept clear and marked, and exits are unobstructed and clearly signed.
• Fire and first aid points: extinguishers, a fire blanket and the first aid box are placed where they can be reached quickly, and are marked with signs.
• Lighting and power: the lighting is bright enough to see the work, and cables are routed overhead or protected where they cross the floor.

1.1.9 Workplace procedures

A procedure is a set of agreed steps for doing a task safely and consistently. Workplace procedures tell each person what they must do, in what order, and who is responsible. They are most useful when they are written, simple and taught to new workers.

1.1.9.1 Roles and responsibilities

• Employer or workshop owner: provides a safe workplace, equipment, training and protective equipment, and ensures that the law is followed.
• Supervisor or instructor: explains the rules, checks that they are followed and stops unsafe work.
• Safety officer or committee: carries out inspections, investigates accidents and advises on improvements.
• Welder or trainee: follows the rules, uses the protective equipment, looks after the equipment and reports hazards, accidents and near misses.

1.1.9.2 Compliance

Compliance is meeting the requirements of the law, the standards and the workshop's own rules. It is checked by regular inspections of the equipment and the work, by safety audits and by training records. Gaps that are found are listed, given an owner and a date, and followed up until they are closed.

Compliance also means the welding itself meets the specification. A welder follows the welding procedure for the job, which states the wire, gas, current and technique to be used, and does not change it without approval.

1.1.9.3 Documentation

Documentation is the written record that proves work was done safely and correctly. The main records are the risk assessments, the welding procedure specifications (WPS), training records, equipment inspection and maintenance logs, work permits for hot work, the accident register and the record of cylinder issue and return.

Good records are dated, signed, kept in a known place and easy to find. They show an inspector that the workshop follows the law, and they supply information for improving the work.

1.1.9.4 Communication

Safety communication makes sure that everybody knows the hazards and the rules at the time when they need them.

• Induction: a briefing for each new person on the first day.
• Toolbox talks: short talks before work starts, on one safety topic.
• Signs and notices: warnings and instructions displayed where they apply.
• Verbal instructions: clear, repeated back to confirm they were understood.
• Reporting routes: a simple route for workers to pass on hazards and ideas.

1.1.9.5 Emergency procedures

An emergency procedure tells each person what to do in the first minutes of a fire, an electric shock, a gas leak or a serious injury. It is displayed, practised in drills and understood by all.

1. Raise the alarm so that everyone nearby is warned.
2. Make the area safe if this can be done without risk, by switching off the power and closing the cylinder valve.
3. Use an extinguisher on a small fire only if the way out is clear, and otherwise leave.
4. Evacuate to the assembly point and check that everybody is present.
5. Give first aid: cool a burn with clean running water, rinse the eyes, and do not touch a person in contact with live electricity until the power is off.
6. Call the emergency services on 999 or 112 and give the place and nature of the emergency.
7. Report and record the event afterwards.

1.1.10 Welding hazards

The hazards below arise directly from welding, and each has its own controls.

1.1.10.1 Fire/Burns

Sparks, spatter and hot metal can set light to flammable materials such as paper, wood, oil, solvents and cloth, and can burn the skin. Hot metal looks the same as cold metal, so burns happen when it is touched too soon.

• Clear flammable materials from within the welding area, or cover them with fire blankets.
• Keep a suitable fire extinguisher within easy reach, and know how to use it.
• Wear the flame-resistant clothing, gloves and boots, with no gaps at the neck, wrists or ankles.
• Mark hot work pieces with chalk, and use tongs and pliers to handle them.
• Check the area for smouldering material for some time after the work is finished.

1.1.10.2 Cuts

Cuts come from sharp edges and burrs on cut plate, from wire ends, from grinding and from broken discs. They can become infected, so any cut is cleaned and covered promptly.

• Wear gloves, and carry plate with the hands clear of the edges.
• Deburr cut edges before the work is handled.
• Cut the wire end with proper cutters, and keep a hand away from the wire coming out of the torch.
• Use guards on the grinder, and fit discs that match the grinder.
• Keep a first aid box in the workshop, and make sure that everybody knows where it is.

1.1.10.3 Fumes

MIG welding fumes are a mixture of tiny metal particles and gases. The fumes of mild steel contain iron and manganese oxides. Welding on galvanised steel gives zinc fumes that cause metal fume fever, and welding on stainless steel gives chromium compounds. The arc also produces ozone and nitrogen oxides, and the heat of the arc can break down solvents left on the metal into poisonous gases.

• Use local exhaust ventilation close to the arc, and keep the head out of the fume plume.
• Remove paint, coatings and solvents from the weld area before welding.
• Wear a respirator suited to welding fume when extraction is not enough or in confined spaces.
• Never weld in a confined space without ventilation and a second person outside.
• Be aware that shielding gas such as argon displaces the air, so a closed space can have too little oxygen.

1.1.10.4 Noise

Noise from grinding, chipping, hammering and compressed air can damage hearing, and the damage builds up slowly, so it is often not noticed until it is permanent. Noise is a risk if people have to raise their voice to be heard at arm's length.

• Choose quieter tools and methods where possible.
• Maintain the machines, because worn bearings and loose parts make more noise.
• Put noisy work in a separate area, or behind barriers.
• Wear ear defenders or ear plugs for grinding and chipping.
• Limit the time spent in noisy work.

1.1.10.5 Gas explosion

Compressed gas cylinders hold gas at very high pressure. A cylinder that is damaged, dropped, overheated or has its valve knocked off can burst, or can be thrown across the workshop like a rocket. Gas leaks also build up in closed spaces, and a fuel gas leak near an arc can ignite and explode.

• Store cylinders upright, chained or strapped, with the valve caps on.
• Keep them away from heat and sparks, and out of the way of vehicles.
• Move them on a cylinder trolley and never roll or drag them.
• Check the connections for leaks with a leak detection solution and not with a flame.
• Close the valve at the cylinder after work, and release the pressure from the regulator.
• Keep oil and grease away from cylinder valves and regulators.

1.1.11 Housekeeping

Housekeeping is the daily work of keeping the workshop tidy, clean and in order. A clean workshop is a safe workshop, because most slips, trips and fires start with something left in the wrong place.

1.1.11.1 Cleaning

Cleaning is part of the daily routine, and it is done at the end of each job and at the end of each day.

• Sweep up spatter, offcuts and wire ends, and wipe up oil and water at once.
• Wipe the machine, torch and bench, and keep the cooling vents of the power source clear of dust.
• Clean the nozzle and contact tip on the torch, and tidy the cables and hoses.
• Put tools back in their places, and keep gangways and exits clear.
• Check that no hot or smouldering material is left, and switch off the machine and the gas.

1.1.11.2 Waste management

At the bench, housekeeping means putting each kind of waste into the correct container as it is made, in line with the system described under Workshop waste management. Metal scrap goes into the scrap bin, spent wire and packaging into the recycling bin, and rags and cloths soaked in oil or solvent into a closed metal bin, because they can ignite by themselves. Hazardous waste is never left on the floor or on the bench, and the bins are emptied at the end of each day so that they do not overflow.

Chapter Summary

This chapter covers the comprehensive process of carrying out Metal Inert Gas (MIG) welding with a focus on occupational health and safety standards, including legislation, hazard identification, risk assessment, and proper incident reporting. It emphasizes the importance of workplace ergonomics, waste management, environmental safety, and adherence to workshop safety regulations, including the use of personal protective equipment and emergency procedures. The interpretation of welding drawings is explained through dimensions, tolerances, and symbols that guide accurate fabrication. Essential MIG welding equipment and accessories are described along with their proper use and maintenance. Preparation of welding materials involves precise measuring, marking, cutting, and edge preparation for metals ranging from 0.1 to 16 mm thickness. Detailed welding parameters such as working pressure, current, torch angle, and wire feed speed are outlined, alongside the different modes of metal transfer including short circuit, globular, spray arc, and pulsed. The chapter also explores the role of shielding gases such as argon and helium, the types of metallic materials suitable for MIG welding, and various welding positions and their applications. Essential weld joint types are classified with their geometry and practical use, followed by an in-depth look at common weld defects, their causes, and prevention methods. Finally, finishing processes such as buffing, polishing, grinding, and painting are discussed to ensure quality and durability of the welded components.