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Welding and Flame Cutting Hazards

Published: 17th Dec 2013

Welding and flame cutting is extremely dangerous. So much so that there is a whole section dedicated to welding in South Africa’s Occupational Health and Safety Act's General Safety Regulations. In this article Mariaan Smit addresses the impact of welding on workers’ health.

Welding is not a straightforward hazard since there are many chemicals to consider. Certain questions need to be asked, such as:

• Is the object that you are going to weld on made of copper, aluminium or steel?

• Is the object that you are going to weld on coated with paint, lead or tar?

• What gases will be used during the welding process? Nitrogen oxide, propane and carbon monoxide, for example, are all dangerous to welders’ health

All these factors cause different health hazards during the welding process, as when melted these substances can enter the lungs. The radiation generated during the welding process also needs to be considered.

Health factors when welding and flame cutting

When a metal’s temperature is raised above melting point it starts to condense in the air. During the condensation period the metal forms dust particles so small that they can be breathed deeply into the lungs. The welding fumes may compose particles that contain chromium, copper, manganese and iron, depending on what is being welded.

Exposure to welding fumes over many years may cause a metallic taste in the mouth, a tight feeling in the chest and irritation to the eyes, nose and throat. Work related occupational diseasessuch as occupational asthma or pneumoconiosis (dusty lung) may develop as a result of many years’ exposure to welding fumes.

Metal fumes may also cause the welder to get metal fume fever, also called Monday fever. Typical symptoms of metal fume fever are nausea, headache, painful limbs and thirst. It usually occurs after the welder has had a weekend off and is re-exposed to the fumes when he/she returns to work on a Monday.

Most of the gases used during the welding process are asphyxiants, meaning they cause suffocation. Asphyxiants dilute atmospheric oxygen to below the amount required to maintain sufficient oxygen levels in a person's body. It is therefore important that welding takes place in a well ventilated area to prevent suffocation of the welder. This is also the reason why welders mostly complain of tiredness, as the oxygen in their bodies is suppressed by the gases used during the welding process.

Welding on ferrous alloys creates carbon monoxide, which binds with your red blood cells and prevents the transfer of oxygen from your blood to the cells in your body. Repeated exposure to carbon monoxide could affect your central nervous system, causing dizziness, irritability and impaired memory.

Arc welding emits radiation that causes the surface of your eyes to get ultraviolet burns, which is like being sunburned on your eyes. Ultraviolet production is doubled during gas shielded argon welding. The usual name given for this condition is arc eye.

Welding in confined spaces or enclosed areas can be fatally dangerous and the worker must establish if there are any toxic substances in the air before he/she starts the welding process. If any toxic substances are present the welder must ensure that the air is decontaminated from the substance and stays decontaminated during the welding process. A competent person must give the welder a permit that declares the confined space is free from toxic substances and explosives before welding commences.

Employer’s responsibilities

Your employer must establish and ensure that you are trained in safe work procedures. You must be provided with a face mask that is specifically designed to protect your respiratory system against welding fumes, as a general dust mask will not give you adequate protection.

It is highly recommended that the welder is issued with a respirator rather than a mask to protect them against metal fumes. One could also consider a helmet that is connected to a compressed air supply, which will positively ventilate the air breathed. By using a helmet the contaminant is then prevented from reaching the breathing zone of the welder. This protection must be provided free of charge.

The biggest challenge is not in issuing workers with the required respiratory protective equipment (RPE), but in getting them to wear it. Factors that influence resistance to wearing RPE are environmental heat, heat created by physical labour during the welding process, working behind a face shield that reduces the available space for a mask or respirator, and the size and weight of the equipment.

Prior to providing respiratory protection, employers must first change welders’ attitudes by providing health risk related training. The power of knowledge will break down resistance.

In accordance with the South African Occupational Health and Safety Act, your employer must have the air tested by an approved person to determine the levels of metal fumes to which you are exposed.

Your employer must supply you with the following protective clothing free of charge: body protection, hand protection, eye protection, face protection, foot protection, and respiratory protection. This is stipulated in the General Safety Regulations of the Occupational Health and Safety Act, of which your employer must have a copy available to show you on request.

If you are a production welder, your employer can install an exhaust ventilation system as close as possible to the source of welding to extract the fumes.

If you are a maintenance welder, your risk is much higher as your environment is constantly changing. Your employer will expect you to carry out a risk assessment before you start welding. Your employer must send you for medical examinations.

Employees' health responsibilities

You must look after your personal protective clothing and ensure that you wear all of it during the welding process. You must ask your health and safety representative to show you the correct way to apply the mask to your face.

Employees must also ensure that they:

• Always conduct a risk assessment before commencing welding in a new environment

• Never start welding in a confined space without the permit issued by a competent person

• Always attend scheduled medical examinations

• Undergo a medical surveillance programme if exposed to significant levels of welding fumes

• Know the contents of the safe work procedures

Welding risk assessment

Usually the risks are determined by the occupational hygienist who must conduct hygiene surveys every two years. As with the medical surveillance of the welder or flame cutter, the health risk assessment and air sampling is not straightforward.

The following questions should be answered prior to the survey in order to ensure that nothing is missed: 1. What are the raw materials? 2. What is produced? 3. What products are formed in the process? 4. What byproducts are released? 5. Where is the main activity to be conducted; for example, inside a confined space, inside the workplace or outside?

The occupational hygienist should perform air sampling of both the environment and breathing zone of the welder. This is one pertinent marker in determining that airborne contaminant levels are within the allowable limits.

Ventilation of the welding area

Natural ventilation should only be accepted when the plume is directed away from the breathing zone of the welder and when air sampling of the breathing zone indicates that the airborne contaminant levels are within the allowable limits.

Natural ventilation should meet the following standards:

• The space provided per welder should be more than 284m³

• The ceiling height should be 5m or higher

• Welding should not be done in a confined space, e.g. inside a drum, a closed container or a pipe

Mechanical ventilation such as local exhaust ventilation and local forced ventilation can be applied in the welding area. In the case of local exhaust ventilation, moveable or fixed exhaust hoods are placed as near as possible to the welding activity.

Local forced ventilation, on the other hand, is a local air moving system; for example, a fan that distributes the air at a 90 degree angle across the welder’s face, with an air velocity of at least 30m per minute at a distance of 0.6m. Local forced ventilation has the risk of distributing the contaminants to other work areas.

Welding and cutting in confined spaces

The General Safety Regulations of South Africa’s Occupational Health and Safety Act 1985 and 1993 regulate the safety of employees expected to perform work inside a confined space:

• A competent person should test the air inside the confined space and issue a certificate in writing that the confined space is safe and will remain safe while any person is within the confined space

If the previously mentioned is not possible and a hazardous gas, vapour, dust or fume may exist, or the oxygen content is less than 20% by volume, a worker can only enter the confined space if it is:

• Purged and ventilated to provide the required safe atmosphere and measures are taken to maintain the safe atmosphere

• Isolated from all pipes, ducts and other communicating openings in a manner as required by this regulation

Where the aforementioned cannot be complied with, the following shall apply:

• Employees entering the confined space should wear a safety harness with a rope securely attached, of which the free end must be outside the confined space

• A person trained in resuscitation should remain outside the confined space in case of any incident happening inside the confined space

• At hand outside the confined space should also be breathing apparatus and resuscitation equipment that is approved by the chief inspector

The employee must vacate the confined space immediately upon completion of any work. If gases, vapours, dust or fumes are present within the confined space that are explosive or flammable in nature, the following steps should be taken prior to entry:

• The concentration of the gases, fumes, vapours or dust must not exceed 25% of the lower explosive limit (LEL)

• The work must be of such a nature that it does not create any source of ignition

• The concentration should not exceed 10% of the LEL of the gases, fumes, vapours or dust

Welding work often needs to be done inside confined spaces. The welder and the assistant welder should keep in mind that no welding, flame cutting, grinding or soldering work can be done either inside or outside on any tube, tank, drum, vessel or similar container if:

• The container is completely closed - unless it is proved that a rise in internal pressure will not render any danger to the worker or the environment

• The container contains any substance that may ignite or explode

• A reaction may take place that can form dangerous or poisonous substances

Activities on the above prohibitions can only take place once a competent person pronounces in writing, after careful examination, that such danger as mentioned previously has been removed by means of opening, ventilating or purging with water, steam or any other effective means.

The welder should take special precautions if welding or flame cutting was stopped for a period inside a confined space. When possible, remove the torch and hose from the confined space when leaving the area, always disconnect the power to arc welding or cutting units and remember to remove the electrode from the holder. Also remember to shut off the gas supply at a point outside the confined space and to turn off the torch valves of all gas welding or cutting units.

Gas detection systems

When entering a confined space remember to make sure your portable gas detector can simultaneously display and monitor multiple gases such as combustibles, oxygen, carbon monoxide and hydrogen sulphide.

A good portable gas detector will have the additional features of being dust proof and waterproof. Ensure that the gas detector has an audible alarm and alarm LEDs so that the user will be alerted to danger immediately, especially in high noise environments.

The question is, which option is best to use for gas monitoring – portable or fixed units? To get to a workable safe answer, one can ask the following questions:

• What are the atmospheric hazards present?

• What is the source of the atmospheric hazard?

• Are the atmospheric hazards a chronic problem?

• Which areas are affected?

• How much time do workers spend in the affected area?

• Is the area restricted with control measures, e.g. permits required prior to entry?

• What finances are available for gas detection?

• What are the calibration and maintenance intervals between the fixed and portable gas detection monitoring systems?

Necessary medical examinations

1. Before you start working at a company, or within the first 30 days after starting, you must get an entry medical examination. This examination must include a chest X-ray as well as a lung function test, to determine possible pneumoconiosis and possible damage to the normal ventilation of your lungs, respectively. This is also your proof of the status of your health before starting work at the company and is therefore also called your baseline medical.

2. You then need to get a chest X-ray and a lung function test every year or biennially, depending on the recommendations of your company’s occupational health sister or medical practitioner, to detect early deterioration of your lungs. This is important since lung disease is mostly irreversible. Your eyes and skin also need to be checked as welding poses a radiation risk.

Horizontal vision screening must form part of the medical surveillance, as the radiation exposure during the welding and flame cutting processes may cause cataracts. Loss in horizontal vision may be a sign of early cataracts.

3. If you are exposed to arsenic, cadmium, chromium, lead, fluorides or carbon monoxide you will require biological monitoring. This means that either a blood or urine sample must be collected from you and sent to a laboratory to determine whether these substances have damaged your body.

4. When you leave the service of the company, an exit medical examination needs to be conducted for the same reasons that the entry medical examination was done.

5. The medical examiner should always remember that people react differently to the same contaminants and exposures. Some people have a higher tolerance than others and genetic susceptibility should also be kept in mind. Non occupational exposure, for example, in the welder who welds at home for an extra income, is a variable that should be kept in mind when occupational diseases are considered.

Conclusion

Welding hazards come in many forms. To protect your health it is important that you undertake the necessary safety steps every single time you conduct welding and flame cutting work. Do not risk complacency – or your next weld could be your last.

Published: 17th Dec 2013 in Health and Safety Middle East

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