Protecting yourself when performing welding operations depends on your understanding of the hazards involved and the proper way to control them. Controlling welding hazards includes
avoiding eye injury, respiratory protection, ventilation of the work area, protective clothing, and having safe equipment to use.
Welding Safety – Texas A&M FabLab Click to play video
Oxy-acetylene Welding/Cutting: Oxy-acetylene welding or cutting is also called torch or gas welding or cutting. Two metals are joined by melting or fusing their adjoining surfaces in the
process. This is done by directing a flame from burning gas (usually acetylene) to melt metal at a joint to be welded, and is a common method for welding iron, steel, cast iron, and copper.
Since gas welding is slower and easier to control than electric arc welding, it is commonly used in general maintenance work, brazing, and soldering.
Equipment: Oxyacetylene equipment consists of a cylinder of acetylene, a cylinder of oxygen, two regulators, two lengths of hose with fittings, a welding torch with tips, and
either a cutting attachment or a separate cutting torch. Accessories include a friction igniter to light the torch, an apparatus wrench to fit the various connections on the regulators, the cylinders,
and the torches; goggles with filter lenses for eye protection; and gloves for protection of the hands. Flame-resistant clothing is worn when necessary.
Acetylene: Acetylene (chemical formula C2H2) is a fuel gas made up of carbon and hydrogen. When burned with oxygen, acetylene produces a very hot flame, having a temperature
between 5700°F and 6300°F. Acetylene gas is colorless, but has a distinct, easily recognized odor.
MAPP Gas: MAPP (methylacetylene-propadiene) gas is an all-purpose industrial fuel that has the high flame temperature of acetylene and the handling characteristics of propane.
MAPP is not sensitive to shock and nonflammable in the absence of oxygen. There is no chance of an explosion if a cylinder is bumped, jarred, or dropped. The cylinders may be stored or
transported in any position with no danger of an explosive air pocket being formed.
MAPP toxicity is rated “very slight,” but high concentrations (5,000 ppm) may have an anesthetic effect. Local eye or skin contact with MAPP gas vapor causes no adverse effect. However,
the liquid fuel will cause dangerous frostlike burns due to the temperature at which MAPP gas should be stored.
Oxygen: Oxygen is a colorless, tasteless, odorless gas that is slightly heavier than air. Oxygen will not burn by itself, but it will support combustion when combined with other gases.
Take extreme care to ensure compressed oxygen does not become contaminated with hydrogen or hydrocarbon gases or liquids.
A highly explosive mixture will be formed if uncontrolled compressed oxygen becomes contaminated. Oxygen should NEVER come in contact with oil or grease.
Oxygen cylinders are supplied in several sizes. The size most commonly used 9 1/8 inches in diameter, weighs about 145 pounds, and has a capacity of 200 cubic feet. At 70°F, the gas is under a
pressure of 1800 psi.
1. Why is gas welding commonly used in general maintenance work, brazing, and soldering?
a. Gas welding is slower and easier to control than electric arc welding
b. Electric arc welding is not approved by OSHA for all maintenance
c. Electric arc welding is slower and hard to control than gas welding
d. Gas welding is less expensive and hazardous
Arc welding is the process in which fusion is produced by heating with an electric arc that is generated between an electrode and the surface of the base metal.
Arc cutting is the process in which the cutting or removal of metals is done by melting with the heat of an arc between an electrode and base metal.
Arc welding and cutting types include:
Flux Core Arc Welding (FCAW) is an arc welding process where coalescence is produced by heating with an arc between a continuous filler metal electrode and the work.
Submerged Arc Welding (SAW) also known as Sub Arc and automatic welding. This is an arc welding process which produces coalescence by heating with an arc or arcs between a bare metal
electrode or electrodes and the work.
Shielded Metal Arc (SMAW) is an arc welding process which produces coalescence by heating with an electric arc between a covered metal electrode and the surface of the base metal.
Gas Metal Arc (GMAW or MIG): This is also called stick welding. This is an arc welding process where coalescence is produced by heating with an arc between a continuous
filler metal electrode (typically a steel alloy wire) and the work.
Gas Tungsten Arc/Tungsten Inert Gas Welding (GTAW or TIG), also called Heli-arc welding, is an arc welding process where coalescence is produced by heating with an arc
between a single tungsten electrode and the work.
Plasma Arc Welding, also called plasma welding, is an arc welding process similar to gas tungsten arc welding (GTAW). The electric arc is formed between an electrode
(which is usually but not always made of sintered tungsten) and the workpiece.
Plasmas Arc Cutting: This is also called plasma cutting. The metal is cut by melting a localized area with a constricted arc and removing the molten material with a
high-velocity jet of hot, ionized gas in this process.
Carbon Arc Cutting: This is also called Arc Gouging and Air-arcing.
Thermite welding: Thermite welding uses a chemical reaction to produce intense heat instead of using gas fuel or electric current.
Pressure welding: Pressure welding uses heat along with impact-type pressure to join the pieces.
Laser Welding: Laser welding uses a focused beam of light to achieve very precise welds. The major hazard of this powerful beam is to the eyes, which can be partially blinded
when hit with the beam. Special eye protection must be used, and care must be taken with any reflective surfaces since both the original and reflected beams are extremely dangerous.
Electron Beam Welding: This method uses a focused beam of electrons to produce high precision and deep penetration welds. Since x-rays are produced as a by-product, the process
should be enclosed and shielded with lead or other materials suitable for preventing x-ray exposure. All doors, ports, and other openings must have proper seals and should be checked periodically
to prevent x-ray leakage.
Operators should wear film badges to detect accidental radiation exposure. The high voltages required also present an electrical hazard.
Robot Welding: Many industries are beginning to use robot welders in place of human workers on the assembly line. This removes workers from the hazard but focuses on job elimination rather than workplace improvements.
In 2013, an employee was prepping steel using a grinder. He was working by himself on the first level of an oil rig platform sub-base. Another Fitter/Welder was working
on the second level of the platform, while the crew supervisor was working on the second level of the platform. The worker was using a grinder and was standing inside a recessed box, where
the oxygen acetylene torch hoses were also present. A leak from the acetylene hose provided the fuel source and a spark from the grinder provided the ignition source for a flash fire to occur.
This fire resulted in serious burns to his legs and feet. He was admitted to the hospital for ten days for burn injuries. The investigation concluded the fire occurred due to a defective splice
on the acetylene hose that allowed the acetylene to leak, causing a fire and the serious injury.
3. Which type of welding uses a chemical reaction to produce intense heat instead of using gas fuel or electric current?
a. Arc welding
b. Pressure welding
c. Laser welding
d. Thermite welding
Avoid the possibility of dangerous electric shock by using insulated electrode holders and wearing dry leathers and gloves.
When possible, avoid using arc-welding equipment in wet or damp areas.
Never perform arc-welding in an area that is not well ventilated.
Arc flash: How to protect yourself Click to play video
Flying Sparks and Molten Metal
Flying sparks usually accompany arc welding. These present a hazard if they strike unprotected skin, lodge on flammable clothing, or hit any other flammable material.
When arc welding, wear suitable weight clothing and cuff less trousers.
Cover pockets so they will not collect sparks, and remove any flammable materials, such as matches, plastic combs, or gas lighters.
Wear the proper foot protection. Wear high top boots with steel toes.
Hot Metal and Burns
Hot metal will cause severe burns. Never handle it with bare hands until it has cooled naturally or has been quenched in the quenching tank. Therefore, use leather gloves with tight fitting cuffs that fit over the sleeves of the jacket. Many welders wear a full set of leather protective clothing, called "leathers."
An employee was tasked to pin weld the inside insulation of the metal duct and wipe the surface with a propanol solution for shipment. The employee noticed
that one pin weld of the duct failed. He decided to replace the defective pin. When he drove a new weld, the sparks from the weld ignited the residue of the propanol on his glove.
His right hand caught fire and caused second-degree burns.
5. What should welders do to prevent being injured by flying sparks?
a. Never cover pockets that might collect sparks
b. Wear log-top boots with leather toes
c. Use gloves with loose-fitting cuffs
d. Wear cuffless trousers
Health effects of exposure to welding fumes and gases.
The welding process produces visible smoke that contains harmful metal fume and gas by-products. Welding fumes are made of very small solid particles, that are the result of welding consumables, base metals, and base metal coatings.
The health effects of exposure to welding fumes can be rather mild to serious in the short term, but if a welder is exposed long-term, the effects can be very serious or fatal.
Acute exposure. Short-term exposure to welding fume and gases can result in eye, nose, and throat irritation, asthma, dizziness and nausea. Workers in the area who experience these symptoms should leave the area immediately, seek fresh air and obtain medical attention.
Chronic exposure. Long-term exposure to welding fume may eventually cause lung damage and various types of cancer, including lung, larynx and urinary tract.
Health effects. Health effects from certain fumes may include metal fume fever, stomach ulcers, kidney damage and nervous system damage. Prolonged exposure to manganese fume can cause Parkinson's-like symptoms.
Suffocation. Gases such as helium, argon, and carbon dioxide displace oxygen in the air and can lead to suffocation, particularly when welding in confined or enclosed spaces. Carbon monoxide gas can form, posing a serious asphyxiation hazard.
6. Prolonged exposure to welding fumes may eventually cause _____.
a. eye, nose, and throat irritation
b. lung damage and cancer
c. dizziness and nausea
d. headache and irritability
There are three types of welding gases: shielding, process, and fuel.
Shielding gases protect the weld area from oxygen, water vapor, carbon dioxide, and nitrogen, that can damage the weld. Air in the weld zone is displaced by a shielding gas in order to prevent contamination of the molten weld puddle.
The types of welding in which shielding gases are use include Metal Inert Gas (MIG) and Tungsten Inert Gas (TIG) welding. Improper choice of a welding gas can lead to a porous and weak weld, or to excessive spatter.
The hazards involved in using shielding gases involve primarily handling gas cylinders. For more information on compressed gas cylinder safety, see OSHA's Small Business Handbook.
Shielding gases include:
inert, non-reactive gases that do not change or create changes when in contact with other substances or temperatures (argon, carbon dioxide, and helium); and
semi-inert, low reactive gases that create changes of state in the other substances and/or themselves (nitrogen carbon dioxide, oxygen, and hydrogen).
Process gases are generated during the welding process (nitrogen oxides, carbon monoxide, ozone, carbon dioxide, hydrogen chloride, and phosgene) and as a result of the breakdown of coatings during welding (hydrogen cyanide, formaldehyde, carbon dioxide, carbon monoxide, isocyanate, and phosphine).
Fuel gases are used in welding and cutting processes. They include acetylene, propane, and butane. Oxygen is also used with fuel gases.
7. Which type of welding gas is used to protect the weld area from water vapor and gases that can damage the weld?
a. Shielding gases
b. Process gases
c. Reactive gases
d. Fuel gases
Forced air ventilation is necessary for welding in confined spaces.
To reduce exposure to the hazards of exposure to welding fumes and gases, welders must understand the hazards of the materials they are working with. Let's look at some of the way to reduce exposure when welding.
OSHA's standard, 1910.1200, Hazard Communication, requires employers to provide information and training for workers on hazardous materials in the workplace.
Welding surfaces should be cleaned of any coating that could potentially create toxic exposure, such as solvent residue and paint.
Workers should position themselves to avoid breathing welding fumes and gases. For example, workers should stay upwind when welding in open or outdoor environments.
In work areas without ventilation and exhaust systems, use natural drafts along with proper positioning to keep fumes and gases away from welders and others.
Keep fume hoods, fume extractor guns and vacuum nozzles close to the plume source to remove the maximum amount of fume and gases. Portable or flexible exhaust systems can be positioned so that fumes and gases are drawn away from the welder.
Consider substituting a lower fume-generating or less toxic welding type or consumable.
Do not weld in confined spaces without forced-air ventilation. Natural ventilation is usually not adequate.
Use respiratory protection if work practices and ventilation do not reduce exposures to safe levels.
8. What method should be used to reduce the level of fumes and gas while welding in a confined space?
a. Positioning upwind from the welding
b. Use a respirator
c. Natural ventilation
d. Forced-air ventilation
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