Welding and cutting operations are widely used in manufacturing and engineering environments.
Fire is the principle hazard and can arise from the leakage of gases from the hoses catching fire or from the ignition of nearby flammable materials by the heat associated with welding (hot surfaces and sparks, etc).
Typical hazards associated with welding operations
There are several typical hazards associated with welding operations, including: Fire; molten metal and sparks; exposure to UV light; hot surfaces; exposure to substances hazardous to health; pressurised systems; electricity and slips, trips and falls
Fire: Welding creates hot surfaces, sparks and emissions of molten metals so there is always a risk of fire. Gas welding operations involve the use of a fuel (acetylene, propane, etc.) and so increase the risks of fire further. Leaking valves or failure to isolate the system correctly may lead to fuel in air build up. Leakage of oxygen can be dangerous as this may lead to an oxygen enriched atmosphere. In oxygen enriched atmosphere, materials are more readily combustible than under normal conditions. Accidents may occur when drums or tanks that have previously contained flammable substances are welded or cut as even with empty tanks, the heat can vaporise residues that will be ignited by the cutting or welding flame. The resulting explosion blows the drum apart, potentially causing serious or even fatal injury.
Molten metal and sparks: Welding operations generate sparks and emissions of molten metals, which may cause fires or can cause injury to the skin and eyes.
Exposure to UV light: Exposure to UV light from welding operations can cause damage to the eyes including a condition known as “arc eye”.
Hazardous substances: Welding fume comprises of metal oxides (mainly iron oxide) and of irritating gases, such as oxides of nitrogen and ozone. Welding fume can cause irritation and “metal fume fever'”. Long term exposure may lead to lung diseases and increase the risk of occupational asthma and cancer. Welding involving stainless steel increases the cancer risks as the welding fume will contain other metal oxides, such as chromium oxide. Surface coatings on the substrate (material being welded) may also give risk to additional hazardous substances, such as lead, etc.
Pressurised systems: In gas welding there is also the potential danger of the huge amount of energy stored in the cylinder by virtue of the compression of the gas, and fuel gases, which by definition, contain stored chemical energy. Pressurised containers (such as gas bottles for propane, oxygen or for inert gases for arc welding) may explode or give rise to a rapid venting of pressurised gases if damaged.
Electricity: There are risks of electric shock and of electrocution associated with arc welding operations.
Slips, trips and falls: There are risks of injury from slips, trips and falls arising from welding operations, generally as a result of poor housekeeping or of poor cable and hose management.
Risk assessment and control measures
Welding operations must be subject to suitable and sufficient assessment of the risks that they create. As well as the general requirement for risk assessment (created by Regulation 3 of the Management of Health and Safety at Work Regulations 1999) there may be a requirement for risk assessment under other regulations, in particular:
• Control of Substances Hazardous to Health Regulations 2002 for hazardous substances (welding fume and other substances that may be inhaled, ingested, etc.
• Dangerous Substances and Explosive Atmospheres Regulations 2002 for flammable and explosive substances (such as welding gases) that may cause fires and explosions.
• Regulatory Reform (Fire Safety) Order 2005 for the general fire risks associated with welding operations.
Fire: General fire safety precautions should be taken. Care should be taken to prevent to accumulation of combustible materials in areas where welding operations are carried out.
By the nature of the process, it is impossible to eliminate sources of ignition from cutting and welding operations. Precautions must be taken to prevent the build up of dangerous concentrations of flammable and explosive gases (such as acetylene). The condition of regulators, hoses and connections should be checked regularly, including checking for leaks (such as by the use of soap solution). Any damaged, worn or otherwise defective hoses or equipment must be replaced.
Flashbacks may be prevented by proper cleaning of the torch and adequate purging of the equipment before lighting up. There are also proprietary anti-flashback devices that should be fitted.
Prohibit the welding of vessels that may have contained flammable substances. If such vessels need to the welded (or cut) then the work should be controlled carefully (such as through a permit to work system) and the vessels must be fully cleaned and purged before welding.
Give consideration to the safe storage of gas cylinders. Fuel gases (such as LPG and acetylene) should be stored away from the oxygen cylinders in a suitable, secure compound with appropriate warning signs displayed. Gas cylinders should be stored outside of the building and should be separated from the building by a suitable fire wall or separation.
Molten metal and sparks and exposure to UV light: The eyes of welders, and of those working close to them, must be protected from molten metal, sparks and intense light. Welders will normally wear welding goggles (in the case of gas cutting and welding) or welding masks (in the case of arc welding). If other working nearby are at risk from the "flash", then suitable fire proof welding screens should be provided. Exposed skin (such as the hands) must be protected from splashes, sparks and from contact with hot surfaces.
Hazardous substances: Exposure to welding fume can be achieved in several ways. The most appropriate method or methods will be determined by the risk assessment. Control measures include:
• General ventilation – this is appropriate if the amount of welding to be carried out is small and there is sufficient general ventilation available to control, the risks from exposure to welding fume. In some cases, welding operations can be carried out outside.
• Extraction – there are several forms of extraction that can be used. Generally, the welding fume is extracted by a system comprising of a captor hood and a hose leading to a fan. The captor hood needs to be positioned close to the area being welded and the velocity of the air through the system needs to be fast enough to capture the fume and carry it through the extraction system. Welding torches can be fitted with their own high velocity low volume extraction systems that are designed to remove the welding fume as soon as it is generated and before it reaches the welder.
• Respiratory protective equipment – although the use of PPE is considered to be the last resort, it may be necessary to protect welders from exposure to fumes (such as one off welding involving stainless steel) and in cases where the use of extraction equipment may not provide adequate protection. The use of disposable masks (to EN 149 FFP2S) or the use of proprietary welding masks involving filtered air can be considered as part of the risk assessment.
• Restrictions on smoking, eating and drinking - smoking is now prohibited in all workplaces. It is recommended that restrictions are placed on the consumption of food and drink in the welding areas as this may lead to the ingestion of hazardous substances (especially chromium oxides) from the hands.
• General welfare facilities – provide suitable hand washing facilities, including soap and water.
• Health surveillance – this will not protect employees from exposure to hazardous substance. However, appropriate health surveillance will often allow for early identification of symptoms so that additional preventive measures can be taken at an early stage. Where workers are exposed to welding fume, especially welding fume that may contain chromium oxides, the employer should carry out lung function testing. The results of health surveillance must be recorded and records must be retained for 40 years.
Pressurised systems: The dangers associated with pressurise systems in welding operations may be controlled by the proper storage, handling and maintenance of cylinders and their fittings. Particular care must be taken not to damage the gas regulator on the gas bottles. Care should be taken to ensure that cylinders do not become involved in fires; if the metal shell is exposed to intense heat, the internal pressure will increase and the yield strength of the metal will be reduced, with possible splitting of the shell and explosive release and combustion of the contents.
Electricity: Like any other electrical equipment, arc welding sets need proper use, inspection and maintenance. It is important to ensure a proper earth-return from the work piece to the set. Electrical flexes, associated fittings and electrode holders must be properly insulated for outdoor use and there should be a suitable procedure for isolating the electrical power supply near to the welder. All electrical circuits should be fitted with an over-current device, for example, a miniature circuit breaker (MCB). Workpieces should be earthed unless a double insulated transformer is being used, in which case the transformer casing should be earthed and not the workpiece.
Slips, trips and falls: General housekeeping in the work area needs to be managed. In particular, cables and hoses need to be routed such that they do no create tripping hazards. In the case of portable welding equipment, this is largely the responsibility of the welder, but with fixed welding systems, consideration needs to be given to the routing of cables and hoses at the design stage.
Summary
Simple control measures are all that is required to control many of the risks associated with welding operations, although more elaborate control measures are required for more intensive welding operations or for those with special hazardous, such as stainless steel welding.
Typical hazards associated with welding operations
There are several typical hazards associated with welding operations, including: Fire; molten metal and sparks; exposure to UV light; hot surfaces; exposure to substances hazardous to health; pressurised systems; electricity and slips, trips and falls
Fire: Welding creates hot surfaces, sparks and emissions of molten metals so there is always a risk of fire. Gas welding operations involve the use of a fuel (acetylene, propane, etc.) and so increase the risks of fire further. Leaking valves or failure to isolate the system correctly may lead to fuel in air build up. Leakage of oxygen can be dangerous as this may lead to an oxygen enriched atmosphere. In oxygen enriched atmosphere, materials are more readily combustible than under normal conditions. Accidents may occur when drums or tanks that have previously contained flammable substances are welded or cut as even with empty tanks, the heat can vaporise residues that will be ignited by the cutting or welding flame. The resulting explosion blows the drum apart, potentially causing serious or even fatal injury.
Molten metal and sparks: Welding operations generate sparks and emissions of molten metals, which may cause fires or can cause injury to the skin and eyes.
Exposure to UV light: Exposure to UV light from welding operations can cause damage to the eyes including a condition known as “arc eye”.
Hazardous substances: Welding fume comprises of metal oxides (mainly iron oxide) and of irritating gases, such as oxides of nitrogen and ozone. Welding fume can cause irritation and “metal fume fever'”. Long term exposure may lead to lung diseases and increase the risk of occupational asthma and cancer. Welding involving stainless steel increases the cancer risks as the welding fume will contain other metal oxides, such as chromium oxide. Surface coatings on the substrate (material being welded) may also give risk to additional hazardous substances, such as lead, etc.
Pressurised systems: In gas welding there is also the potential danger of the huge amount of energy stored in the cylinder by virtue of the compression of the gas, and fuel gases, which by definition, contain stored chemical energy. Pressurised containers (such as gas bottles for propane, oxygen or for inert gases for arc welding) may explode or give rise to a rapid venting of pressurised gases if damaged.
Electricity: There are risks of electric shock and of electrocution associated with arc welding operations.
Slips, trips and falls: There are risks of injury from slips, trips and falls arising from welding operations, generally as a result of poor housekeeping or of poor cable and hose management.
Risk assessment and control measures
Welding operations must be subject to suitable and sufficient assessment of the risks that they create. As well as the general requirement for risk assessment (created by Regulation 3 of the Management of Health and Safety at Work Regulations 1999) there may be a requirement for risk assessment under other regulations, in particular:
• Control of Substances Hazardous to Health Regulations 2002 for hazardous substances (welding fume and other substances that may be inhaled, ingested, etc.
• Dangerous Substances and Explosive Atmospheres Regulations 2002 for flammable and explosive substances (such as welding gases) that may cause fires and explosions.
• Regulatory Reform (Fire Safety) Order 2005 for the general fire risks associated with welding operations.
Fire: General fire safety precautions should be taken. Care should be taken to prevent to accumulation of combustible materials in areas where welding operations are carried out.
By the nature of the process, it is impossible to eliminate sources of ignition from cutting and welding operations. Precautions must be taken to prevent the build up of dangerous concentrations of flammable and explosive gases (such as acetylene). The condition of regulators, hoses and connections should be checked regularly, including checking for leaks (such as by the use of soap solution). Any damaged, worn or otherwise defective hoses or equipment must be replaced.
Flashbacks may be prevented by proper cleaning of the torch and adequate purging of the equipment before lighting up. There are also proprietary anti-flashback devices that should be fitted.
Prohibit the welding of vessels that may have contained flammable substances. If such vessels need to the welded (or cut) then the work should be controlled carefully (such as through a permit to work system) and the vessels must be fully cleaned and purged before welding.
Give consideration to the safe storage of gas cylinders. Fuel gases (such as LPG and acetylene) should be stored away from the oxygen cylinders in a suitable, secure compound with appropriate warning signs displayed. Gas cylinders should be stored outside of the building and should be separated from the building by a suitable fire wall or separation.
Molten metal and sparks and exposure to UV light: The eyes of welders, and of those working close to them, must be protected from molten metal, sparks and intense light. Welders will normally wear welding goggles (in the case of gas cutting and welding) or welding masks (in the case of arc welding). If other working nearby are at risk from the "flash", then suitable fire proof welding screens should be provided. Exposed skin (such as the hands) must be protected from splashes, sparks and from contact with hot surfaces.
Hazardous substances: Exposure to welding fume can be achieved in several ways. The most appropriate method or methods will be determined by the risk assessment. Control measures include:
• General ventilation – this is appropriate if the amount of welding to be carried out is small and there is sufficient general ventilation available to control, the risks from exposure to welding fume. In some cases, welding operations can be carried out outside.
• Extraction – there are several forms of extraction that can be used. Generally, the welding fume is extracted by a system comprising of a captor hood and a hose leading to a fan. The captor hood needs to be positioned close to the area being welded and the velocity of the air through the system needs to be fast enough to capture the fume and carry it through the extraction system. Welding torches can be fitted with their own high velocity low volume extraction systems that are designed to remove the welding fume as soon as it is generated and before it reaches the welder.
• Respiratory protective equipment – although the use of PPE is considered to be the last resort, it may be necessary to protect welders from exposure to fumes (such as one off welding involving stainless steel) and in cases where the use of extraction equipment may not provide adequate protection. The use of disposable masks (to EN 149 FFP2S) or the use of proprietary welding masks involving filtered air can be considered as part of the risk assessment.
• Restrictions on smoking, eating and drinking - smoking is now prohibited in all workplaces. It is recommended that restrictions are placed on the consumption of food and drink in the welding areas as this may lead to the ingestion of hazardous substances (especially chromium oxides) from the hands.
• General welfare facilities – provide suitable hand washing facilities, including soap and water.
• Health surveillance – this will not protect employees from exposure to hazardous substance. However, appropriate health surveillance will often allow for early identification of symptoms so that additional preventive measures can be taken at an early stage. Where workers are exposed to welding fume, especially welding fume that may contain chromium oxides, the employer should carry out lung function testing. The results of health surveillance must be recorded and records must be retained for 40 years.
Pressurised systems: The dangers associated with pressurise systems in welding operations may be controlled by the proper storage, handling and maintenance of cylinders and their fittings. Particular care must be taken not to damage the gas regulator on the gas bottles. Care should be taken to ensure that cylinders do not become involved in fires; if the metal shell is exposed to intense heat, the internal pressure will increase and the yield strength of the metal will be reduced, with possible splitting of the shell and explosive release and combustion of the contents.
Electricity: Like any other electrical equipment, arc welding sets need proper use, inspection and maintenance. It is important to ensure a proper earth-return from the work piece to the set. Electrical flexes, associated fittings and electrode holders must be properly insulated for outdoor use and there should be a suitable procedure for isolating the electrical power supply near to the welder. All electrical circuits should be fitted with an over-current device, for example, a miniature circuit breaker (MCB). Workpieces should be earthed unless a double insulated transformer is being used, in which case the transformer casing should be earthed and not the workpiece.
Slips, trips and falls: General housekeeping in the work area needs to be managed. In particular, cables and hoses need to be routed such that they do no create tripping hazards. In the case of portable welding equipment, this is largely the responsibility of the welder, but with fixed welding systems, consideration needs to be given to the routing of cables and hoses at the design stage.
Summary
Simple control measures are all that is required to control many of the risks associated with welding operations, although more elaborate control measures are required for more intensive welding operations or for those with special hazardous, such as stainless steel welding.
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