Arc welding is a common and versatile method of joining metal pieces together using an electric arc. However, arc welding also poses significant fire risks due to the high temperatures, sparks, and molten metal involved. According to the National Fire Protection Association (NFPA), welding and cutting operations accounted for an average of 4,440 structure fires per year in the U.S. between 2014 and 2018. These fires resulted in an average of 12 civilian deaths, 208 civilian injuries, and $309 million in direct property damage per year.
Therefore, it is essential for welders and employers to be aware of the potential fire hazards in arc welding and take appropriate measures to prevent and control them. In this article, we will discuss the main causes and sources of fire in arc welding, the best practices and standards for fire safety in welding operations, and the recommended equipment and procedures for fire prevention and suppression.
I. Causes and Sources of Fire in Arc Welding
The main causes of fire in arc welding are:
1) Sparks and slag:
These are the small particles of molten metal that are ejected from the arc and the weld pool. They can travel up to 35 feet from the welding area and ignite any combustible materials they come in contact with, such as wood, paper, cloth, plastic, oil, gas, or dust.
2) Heat and radiation:
The arc and the weld pool generate intense heat and radiation that can raise the temperature of nearby materials and cause them to ignite or smolder. The heat and radiation can also damage electrical wires and equipment, creating short circuits and sparks.
3) Flammable gases:
Some welding processes, such as gas metal arc welding (GMAW) and gas tungsten arc welding (GTAW), use shielding gases such as argon, helium, or carbon dioxide to protect the weld from oxidation and contamination. However, these gases can also displace oxygen in the welding area and create an asphyxiation hazard for the welder and other workers. Moreover, some gases, such as acetylene, hydrogen, or propane, are highly flammable and can explode if mixed with air or oxygen and ignited by the arc or a spark.
The main sources of fire in arc welding are:
1) The workpiece and the work area:
The workpiece is the metal part that needs to be welded, and the work area is the surrounding space where the welding operation takes place. The workpiece and the work area can contain or be near flammable or combustible materials, such as wood, paper, cloth, plastic, oil, gas, or dust. These materials can catch fire from sparks, slag, heat, or radiation generated by the arc welding process.
2) The welding equipment and accessories:
The welding equipment and accessories include the power source, the welding torch, the electrode, the filler metal, the shielding gas, the hoses, the cables, the clamps, and the protective gear. The welding equipment and accessories can malfunction, overheat, or short circuit, creating sparks, flames, or electric shocks that can ignite flammable or combustible materials in the welding area or damage the equipment itself.
3) The welder and other workers:
The welder is the person who performs the arc welding operation, and other workers are the people who assist or supervise the welder or work in the same or adjacent areas. The welder and other workers can accidentally or intentionally cause or spread fire by using improper welding techniques, wearing inappropriate clothing, smoking, or handling flammable or combustible materials or liquids in the welding area.
II. Best Practices and Standards for Fire Safety in Welding Operations
The best practices and standards for fire safety in welding operations are:
1) Follow the OSHA regulations and the NFPA codes:
The Occupational Safety and Health Administration (OSHA) and the NFPA are the main authorities that regulate and provide guidelines for fire safety in welding operations in the U.S. The OSHA regulations for welding, cutting, and brazing are found in 29 CFR 1910 Subpart Q and 29 CFR 1926 Subpart J. The NFPA codes for fire protection in welding, cutting, and other hot work are NFPA 51B and NFPA 326. These regulations and codes specify the general requirements and precautions for fire prevention and protection in welding operations, such as the following:
Conduct a fire risk assessment before starting any welding operation and obtain a hot work permit if required by the employer or the authority having jurisdiction.
Inspect the welding equipment and accessories before and after each use and repair or replace any defective or damaged parts.
Remove or protect all flammable or combustible materials from the welding area or within 35 feet of the welding operation, or as far as possible if more than 35 feet.
Provide adequate ventilation and exhaust systems to prevent the accumulation of flammable gases, vapors, or dusts in the welding area.
Use the appropriate welding process, electrode, filler metal, and shielding gas for the workpiece and the work area.
Adjust the welding current, arc length, and weld speed to the optimal settings for the welding operation and the workpiece thickness.
Wear the proper personal protective equipment (PPE), such as gloves, boots, helmets, goggles, and fire-resistant clothing, to protect yourself from sparks, slag, heat, radiation, and electric shocks.
Have a fire watcher and a fire extinguisher ready and available in the welding area during and after the welding operation.
Follow the emergency response plan and report any fire incidents to the employer and the authority having jurisdiction.
2) Follow the manufacturer’s instructions and recommendations:
The manufacturer of the welding equipment and accessories is the best source of information and guidance for the safe and proper use of their products. The manufacturer’s instructions and recommendations are usually found in the labels, manuals, datasheets, or websites of the welding equipment and accessories. These instructions and recommendations specify the technical specifications, operating procedures, maintenance schedules, troubleshooting tips, and safety warnings for the welding equipment and accessories, such as the following:
Read and understand the labels, manuals, datasheets, or websites of the welding equipment and accessories before using them.
Use the welding equipment and accessories only for their intended purposes and applications.
Do not modify, alter, or tamper with the welding equipment and accessories without the manufacturer’s approval.
Do not use the welding equipment and accessories if they are damaged, defective, or expired.
Store and transport the welding equipment and accessories in a safe and secure manner, following the manufacturer’s instructions and recommendations.
Contact the manufacturer or an authorized service provider if you have any questions, concerns, or issues with the welding equipment and accessories.
III. Recommended Equipment and Procedures for Fire Prevention and Suppression
The recommended equipment and procedures for fire prevention and suppression in welding operations are:
1) Fire extinguishers:
Fire extinguishers are portable devices that contain a pressurized agent that can be sprayed on a fire to extinguish it. Fire extinguishers are classified by the type of fire they can put out, such as Class A (ordinary combustibles), Class B (flammable liquids), Class C (electrical equipment), Class D (combustible metals), and Class K (cooking oils and fats). The recommended fire extinguishers for welding operations are:
A combination fire extinguisher (Class A, B, C) for most welding operations, especially those involving flammable liquids or electrical equipment.
A Class D fire extinguisher or a dry powder agent (such as sand or magnesium foundry flux) for welding operations involving combustible metals, such as magnesium, titanium, or zirconium.
A Class K fire extinguisher for welding operations involving cooking oils and fats, such as in restaurants or kitchens.
The fire extinguisher should be located within 10 feet of the welding area and should be easily accessible and visible.
The fire extinguisher should be inspected and maintained regularly, following the manufacturer’s instructions and recommendations.
The fire extinguisher should be used only when the fire is small, confined, and controllable, and when the welder or the fire watcher has a clear escape route. The fire extinguisher should be used according to the PASS technique, which stands for:
1. Pull the pin or lever that unlocks the fire extinguisher.
2. Aim the nozzle or hose at the base of the fire, not at the flames.
3. Squeeze the handle or trigger to release the fire-fighting agent.
4. Sweep the nozzle or hose from side to side until the fire is out or the fire extinguisher is empty.
The fire extinguisher should be replaced or refilled after each use, following the manufacturer’s instructions and recommendations.
2) Fire blankets:
Fire blankets are non-combustible materials that can be used to smother small fires or to protect people or objects from fire. Fire blankets are usually made of fiberglass, wool, or asbestos. The recommended fire blankets for welding operations are:
A fire blanket that is large enough to cover the entire welding area and any nearby flammable or combustible materials.
A fire blanket that is rated for high temperatures and has a fire-resistant coating or treatment.
A fire blanket that is stored in a convenient and accessible location, such as a wall-mounted container or a bag.
A fire blanket that is inspected and maintained regularly, following the manufacturer’s instructions and recommendations.
A fire blanket that is used only once and replaced after each use.
3) Fire hoses and sprinklers:
Fire hoses and sprinklers are fixed or portable devices that deliver water or other fire-fighting agents to a fire. Fire hoses and sprinklers are usually connected to a water supply system or a fire pump. The recommended fire hoses and sprinklers for welding operations are:
A fire hose that is long enough to reach the welding area and any nearby flammable or combustible materials.
A fire hose that has a nozzle that can adjust the water pressure and spray pattern.
A fire hose that is stored in a coiled or rolled position and is protected from damage and deterioration.
A fire hose that is inspected and tested regularly, following the manufacturer’s instructions and recommendations.
A fire sprinkler system that is installed and designed according to the NFPA 13 standard and the local fire codes.
A fire sprinkler system that is activated automatically by a heat or smoke detector or manually by a pull station or a valve.
A fire sprinkler system that is inspected and maintained regularly, following the manufacturer’s instructions and recommendations.
4) Fire alarms and detectors:
Fire alarms and detectors are devices that alert people of a fire by producing a loud sound, a flashing light, or a verbal message. Fire alarms and detectors are usually triggered by a heat or smoke sensor or a manual switch. The recommended fire alarms and detectors for welding operations are:
A fire alarm system that is installed and designed according to the NFPA 72 standard and the local fire codes.
A fire alarm system that is connected to a central monitoring station or a local fire department.
A fire alarm system that has audible and visible signals that can be heard and seen throughout the welding area and the adjacent areas.
A fire alarm system that has manual pull stations or switches that can be easily accessed and operated by the welder and other workers.
A fire alarm system that is inspected and tested regularly, following the manufacturer’s instructions and recommendations.
A fire detector that is suitable for the type of fire that may occur in the welding area, such as a heat detector, a smoke detector, or a flame detector.
A fire detector that is located close to the welding area and any nearby flammable or combustible materials.
A fire detector that is not affected by the welding process, such as the sparks, slag, heat, radiation, or gases.
A fire detector that is inspected and tested regularly, following the manufacturer’s instructions and recommendations.
IV. Conclusion
Arc welding and fire safety are closely related and should be taken seriously by welders and employers. By following the OSHA regulations and the NFPA codes, the manufacturer’s instructions and recommendations, and the best practices and standards for fire prevention and suppression, you can reduce the risk of fire in welding operations and protect yourself, your coworkers, and your property from fire hazards. Remember to always be alert, cautious, and prepared when performing arc welding. Stay safe and happy welding!
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