ADVANCE INSTITUTE OF SAFETY ENGG.
What is welding?
Welding is the process of permanently joining two or more materials together, usually metals, by heat or pressure or both. When heated, the material reaches molten state and may be joined together with or without additional filler materials being added. Thermoplastics, for example can be welded together using a suitable heat source to form permanent joins. Many different energy sources can be used for welding including gas flames, electric arcs, electric resistance, lasers, electron beams, friction, molten metal baths and ultrasound. Welding includes joining methods as diverse as fusion welding, forge welding, friction welding, braze welding, brazing, soldering and explosion welding. Welding is a potentially hazardous activity and precautions are required to avoid electrocution, fire and explosion, burns, electric shock, vision damage, inhalation of poisonous gases and fumes, and exposure to intense ultraviolet radiation.
Be Prepared: Four Potential Welding Safety Hazards to Avoid
Safety is a critical consideration for any welding project. Arc welding is a safe occupation when proper precautions are taken. But, if safety measures are ignored, welders face an array of hazards which can be potentially dangerous, including electric shock, fumes and gases, fire and explosions and more.
To help keep welders safe, organizations such as the American Conference of Governmental Industrial Hygienists (ACGIH) and the Occupational Safety and Health Administration (OSHA) offer safety guidelines to help control, minimize or to help employers and workers avoid welding hazards. Employers should ensure all workers have an opportunity to comply with the following important guidelines in the workplace:
- Read and understand manufacturer instructions for equipment.
- Carefully review material safety data sheets.
- Follow the company’s internal safety practices.
Awareness of the most common welding hazards and knowing how to avoid them ensures a safe, productive work environment for all.
1) ELECTRIC SHOCK
Electric shock is one of the most serious and immediate risks facing a welder. Electric shock can lead to severe injury or death, either from the shock itself or from a fall caused by the reaction to a shock.
Electric shock occurs when welders touch two metal objects that have a voltage between them, thereby inserting themselves into the electrical circuit. For instance, if a worker holds a bare wire in one hand and a second bare wire with another, electric current will pass through that wire and through the welding operator, causing an electric shock. The higher the voltage, the higher the current and, thus the higher the risk for the electric shock to result in injury or death.
The most common type of electric shock is secondary voltage shock from an arc welding circuit, which ranges from 20 to 100 volts. Bear in mind that even a shock of 50 volts or less can be enough to injure or kill an operator, depending on the conditions. Due to its constant change in polarity, alternating current (AC) voltage is more likely to stop the heart than direct current (DC) welders. It is also more likely to make the person holding the wire unable to let go.
It’s important to remember to never touch the electrode or metal parts of the electrode holder with skin or welding clothing and insulate yourself from the work and ground.
To avoid secondary voltage shock, welding operators should wear dry gloves in good condition, never touch the electrode or metal parts of the electrode holder with skin or wet clothing and be sure to insulate themselves from the work and ground, keeping dry insulation between their body and the metal being welded or ground (such as a metal floor or wet surface).
Welding operators also should inspect the electrode holder for damage before beginning to weld and keep the welding cable and electrode holder insulation in good condition, because the plastic or fiber insulation on the electrode holder prevents contact with the electrically “hot” metal parts inside. Always be sure to repair or replace damaged insulation before use. And remember, stick electrodes are always electrically hot, even when welding is not being done and the voltage is the highest.
An even more serious shock, primary voltage shock, may occur when a welder touches electrically ‘hot’ parts inside the welder case or the electric distribution system to which the welder is connected. This action can lead to a shock of 230 or 460 volts.
When not in use, but still turned on, most welding equipment have a voltage that ranges from 20 to 100 volts at the welding circuit and voltages inside the welding equipment may range from 120 volts to more than 575 volts, all of which pose a risk for electric shock. Only qualified repair technicians should attempt to service or repair welding equipment.
2) Fumes and gases
it’s no surprise that overexposure to welding fumes and gases can be hazardous to your health. Welding fume contains potentially harmful complex metal oxide compounds from consumables, base metal and the base-metal coatings, so it’s important to keep your head out of the fumes and use enough ventilation and/or exhaust to control your exposure to substances in the fume, depending on the type of rod and base metal being used.
The specific potential health effects which relate to the welding consumable product being used can be found in the Health Hazard Data section of the Safety Data Sheet available from your employer or the consumable manufacturer.
Welding areas require adequate ventilation and local exhaust to keep fumes and gases from the breathing zone and the general area. In most situations, employers will provide a ventilation system- such as a fan, and an exhaust system or fixed or removable exhaust hoods- to remove fumes and gases from the work area.
Welding areas require adequate ventilation and local exhaust to keep fumes and gases from the breathing zone and the general area.
All welding operators should be aware that there are ACGIH threshold limit values (TLV) and OSHA permissible exposure limits (PEL) for the substances in welding fume. These limits specify the amount of a substance in your breathing air to which welding operators can be exposed every day they work over the course of their career. Welding operators should wear an approved respirator unless exposure assessments are below applicable exposure limits. An industrial hygienist takes an air sample in the worker’s breathing zone to determine whether a worker’s exposure is below the exposure limits.
If the air in your breathing zone is not clear or if breathing is uncomfortable, check to be sure the ventilation equipment is working and report concerns to a supervisor so your exposure to substances in the welding fume can be checked. This is especially important when welding with stainless steel or hard facing products. To prevent exposure from coatings such as paint, galvanizing, or metal plating’s on base metals, clean the base metal before beginning to weld. See a doctor if symptoms from overexposure persist.
3) Fire and explosions
Welding arc creates extreme temperatures, and may pose a significant fire and explosions hazard if safe practices are not followed. While the welding arc may reach temperatures of 10,000 degrees Fahrenheit, the real danger is not from the arc itself, but rather the intense near the arc and the heat, sparks and spatter created by the arc. This spatter can reach up to 35 feet away from the welding space.
To prevent fires, before beginning to weld, inspect the work area for any flammable materials and remove them from the area. Flammable materials are comprised of three categories: liquid, such as gasoline, oil and paint; solid, such as wood, cardboard and paper; gas, including acetylene, propane and hydrogen.
Fume Exhaust systems can be augmented with a fire safety solution system like the Lincoln Electric Guardian system, designed to aid fire prevention, detection and suppression within the fume control system.
Know where the fire alarms and extinguishers are located, and check the extinguisher’s gauge to make sure it is full. If an extinguisher is not available, be sure to have access to fire hoses, sand buckets or other equipment that douses fire. And, know the location of the nearest fire exit.
If welding within 35 feet of flammable materials, have a fire watcher nearby to keep track of sparks, and remain in the work area for at least 30 minutes after finishing welding to be sure there are no smoldering fires. Put a fire resistant material, such as a piece of sheet metal or fire resistant blanket, over any flammable materials within the work area, if you can’t remove them.
In an elevated location, make sure no flammable materials are beneath you, and watch out for other workers below you in order to prevent dropping sparks or spatter on them. Even high concentrations of fine dust particles may cause explosions or flash fires. If a fire starts, don’t panic – and call the fire department immediately.
4) Injuries from insufficient PPE
Personal protective equipment (PPE) helps keep welding operators free from injury, such as burns – the most common welding injury – and exposure to arc rays. The right PPE allows for freedom of movement while still providing adequate protection from welding hazards.
Thanks to their durability and fire resistance, leather and flame-resistant treated cotton clothing is recommended in welding environments. This is because synthetic material such as polyester or rayon will melt when exposed to extreme heat. Welding leathers are especially recommended when welding out of position, such as applications that require vertical or overhead welding.
Personal protective equipment (PPE) helps keep welding operators free from injury, such as burns – the most common welding injury – and exposure to arc rays.
Avoid rolling up sleeves or pant cuffs, as sparks or hot metal will deposit in the folds and may burn through the material. Keep pants over the top of work boots – don’t tuck them in. Even when wearing a helmet, always wear safety glasses with side shields or goggles to prevent sparks or other debris from hitting the eyes. Leather boots with 6-to-8-inch ankle coverage are the best foot protection; metatarsal guards over the shoe laces can protect feet from falling objects and sparks. It will not be pleasant if a hot piece of spatter finds its way inside your clothing or shoes.
Heavy, flame-resistant gloves should always be worn to protect from burns, cuts and scratches. As long as they are dry, they also should provide some protection from electric shock. Leather is a good choice for gloves.
Helmets with side shields are essential for protecting eyes and skin from exposure to arc rays. Make sure to choose the right shade lens for your process – use the helmet’s instructions to help select the right shade level. Begin with a darker filter lens and gradually change to a lighter shade until you have good visibility at the puddle and weld joint but it is comfortable and does not irritate your eyes. Helmets also protect from sparks, heat and electric shock. Welder’s flash from improper eye protection may cause extreme discomfort, swelling or temporary blindness, so don’t take any risks – wear a helmet at all times during welding.
To protect ears from noise, wear hearing protection if working in an area with high noise levels. Doing so will protect your hearing from damage, as well as well prevent metal and other debris from entering the ear canal. Choose ear plugs or ear muffs to protect the ears.