Key definitions

• Key terms are defined in this section.

To understand the Welding and Cutting topic, it is important to first understand what certain terms mean. These terms, as defined here, are used throughout this topic.

• Approved: Accepted, certified, listed, labeled, or otherwise determined to be safe by a nationally recognized testing laboratory.
• Brazing: Joining metal items by melting a filler metal that has a lower melting point into the joint between them, at a temperature above 840°F (450°C).
• Fire watcher: A worker who is trained on fire hazards and prevention and provides additional safeguards against fire during and after welding, cutting, or heating operations.
• Hot work: Any work that involves burning, welding, or using fire- or spark-producing tools, or that produces a source of ignition.
• Listed: Mentioned in a list that is published by a nationally recognized testing laboratory and states that the equipment meets nationally recognized standards or has been tested and found safe for use.
• Nationally recognized testing laboratory: An organization recognized by the Occupational Safety & Health Administration (OSHA) that tests equipment or materials for safety and lists, labels, or accepts them.
• Soldering: Joining metal items by melting a filler metal that has a lower melting point into the joint between them, at a temperature below 840°F (450°C).
• Welder and welding operator: Any operator of electric or gas welding and cutting equipment.
• Welding: Joining metal items by melting them together, without a filler metal.

Hot work overview

• Welding, cutting, brazing, and similar flame-producing operations are known as “hot work.”
• Hot work requirements include administrative oversight, proper firefighting and other safety equipment, and the use of a fire watch in some cases.

Any time work is performed using equipment that produces a spark or an open flame, or a process that generates excessive heat, there is a risk of fire. Work involving electric or gas welding, cutting, brazing, or similar flame-producing operations is known as “hot work.”

The Occupational Safety & Health Administration (OSHA) doesn’t specifically require companies to have a written permit to perform hot work. However, OSHA prefers that they be used. Many companies choose to have these permits to demonstrate that their hot work program is in compliance. 29 CFR 1910.252 gives general requirements for performing hot work safely.

Some administrative procedures are required before hot work begins:

• If cutting and welding operations will take place in an areas not specifically designed for these processes, employers must designate an individual who is responsible for authorizing them.
• This individual must inspect the area before cutting or welding is permitted.
• Employers must establish precautions to proceed, preferably in the form of a written permit.
• Cutters or welders and their supervisors must be trained in the safe operation of their equipment and the safe use of the process.

In addition to being inspected by the designated individual, the area must be made as hazard-free as possible before hot work begins:

• If there are openings or cracks in the area that can’t be closed, precautions must be taken to keep combustible materials from exposure to sparks that might pass through. Openings may include: cracks or holes in flooring or walls, open doorways, and open or broken windows.
• If the object to be welded or cut can’t readily be moved, all movable fire hazards must be taken away to a safe place.
• If all the fire hazards can’t be removed, the object to be welded or cut must be guarded.

Appropriate safety equipment is required for hot work:

• Suitable fire extinguishing equipment must be kept ready for immediate use.
• Preventative maintenance of specialized tools, warning labels, and ventilation must be conducted on schedule so these things are available and in working order when needed.
• Proper personal protective equipment (PPE) in good condition must be available to and used by welders and cutters.

Some hot work conditions are dangerous enough to require a fire watch:

• Fire watchers must be in place whenever welding or cutting is performed in locations where other than a minor fire might develop.
• The fire watch must be maintained for at least a half hour after welding or cutting finishes to detect and extinguish possible smoldering fires.

Types of welding

Welding is classified into two groups:

• Fusion welding, which uses heat alone and includes: electric arc welding, gas welding, and thermit welding.

• Pressure welding, which uses both heat and pressure and includes: gas pressure welding, friction welding, resistance welding, diffusion welding, ultrasonic welding, and explosion welding.

Requirements for general industry

• Safety requirements for welding, cutting, and brazing in general industry include site hazard assessments, fire prevention procedures, and proper handling of compressed gas cylinders.
• Welding, cutting, and brazing are regulated by OSHA in 29 CFR 1910, Subpart Q, and by ANSI in Z49.1-1967.

Welding, cutting, and brazing are common in many fields. The Occupational Safety & Health Administration (OSHA) regulates these practices in general industry in 29 CFR 1910, Subpart Q.

Some general requirements include administrative controls to be put in place before any hot work begins. Employers must:

• Perform a thorough site hazard assessment,
• Ensure areas are inspected and a permit issued,
• Establish and document emergency procedures,
• Provide suitable ventilation,
• Provide a fire watch where required, and
• Ensure proper marking of welding materials and equipment.

Employers must also train personnel in, facilitate, and enforce safe work practices, including:

• Proper welding procedures, including handling of materials and equipment;
• Handling, storage, and use of compressed gas cylinders;
• Using compressed gases and torches for gas welding and cutting;
• Using arc welding equipment;
• Working in confined spaces; and
• Fire prevention and protection precautions.

All necessary equipment must be provided and maintained in good working condition, including:

• Welding equipment;
• Personal protective equipment (PPE), including respirators and other gear as required;
• Ventilation equipment; and
• Suitable fire extinguishers.

Regulations

The OSHA requirements for welding, cutting, and brazing in general industry are found in 29 CFR 1910, Subpart Q. Specific subtopics include:

• 29 CFR 1910.133 — Eye and face protection.
• 29 CFR 1910.251 — Definitions.
• 29 CFR 1910.252 — General requirements.
• 29 CFR 1910.253 — Oxygen-fuel gas welding and cutting.
• 29 CFR 1910.254 — Arc welding and cutting.
• 29 CFR 1910.255 — Resistance welding.

The following might also be helpful:

• 29 CFR 1926.350 - .354, Subpart J — Welding and Cutting.
• American National Standards Institute (ANSI) Z49.1-1967 — Safety in Welding and Cutting.

Individual states may adopt OSHA’s standards and enforcement programs or use their own. State Plans are required to be at least as effective as OSHA’s and may have different or more stringent regulations. There are 29 OSHA-approved State Plans.

Requirements for the construction industry

• OSHA’s requirements for hot work in the construction industry are similar but not identical to those for general industry.
• Construction employers must provide training in safe welding practices, handling toxic and flammable substances, fire watching, and confined spaces, as applicable to their workers’ duties.

Welding, cutting, and brazing are common in many fields. The Occupational Safety & Health Administration (OSHA) regulates these practices in the construction industry in 29 CFR 1926 Subpart J.

Most requirements for hot work in construction are the same as those in general industry. However, there are some differences, such as whether gas cylinders may be permanently stored on a transport dolly. OSHA says that due to the rougher nature of most construction sites, cylinders must be put into more secure storage if gas is not to be drawn for 24 hours.

Regulations

OSHA’s Subpart J welding requirements apply to any employer performing welding operations during construction activities.

• 29 CFR 1926 — Safety and health regulations for construction.
• 29 CFR 1926, Subpart J — Welding and cutting.
• 29 CFR 1926.350 — Gas welding and cutting.
• 29 CFR 1926.351 — Arc welding and cutting.
• 29 CFR 1926.352 — Fire prevention.
• 29 CFR 1926.353 — Ventilation and protection in welding, cutting, and heating.
• 29 CFR 1926.354 — Welding, cutting, and heating in way of preservative coatings.

General requirements

Construction employers must:

• Provide personal protective equipment (PPE) as needed,
• Provide suitable ventilation,
• Ensure workers’ safety when working in confined spaces,
• Follow safety precautions for fire prevention and protection,
• Maintain suitable fire extinguishers,
• Provide a fire watch where required,
• Maintain welding equipment,
• Ensure proper marking of welding materials and equipment,
• Handle welding materials and equipment properly, and
• Facilitate and enforce proper welding procedures.

Training

Training requirements for welding and cutting that are specific to construction are found in 29 CFR 1926.350, .351, .352, and .354.

Several OSHA regulations apply to training for hot work in the construction industry.

• 1926.350–351 requires gas and arc welders to be trained in the safe use of fuel gas and safe means of arc welding and cutting.
• 1926.352 requires employees assigned to guard against fire during hot work (fire watchers) to be trained in the anticipated fire hazards and the use of the provided firefighting equipment.
• 1926.354 requires a competent person to be trained in how to test surfaces covered by a preservative coating for flammability before welding, cutting, or heating is started.
• 1926.59 requires employers to provide hazard communication training about materials that produce fumes and gases and work areas where such exposure may occur.
• 1926.21 requires employees to be trained in:
  • Recognizing and avoiding unsafe conditions;
  • Any regulations that apply to controlling or eliminating hazards in their work environment;
  • Safe handling and use of any harmful or flammable substances they may be exposed to;
  • The potential hazards, personal hygiene, and personal protective measures required; and
  • The specific requirements in subparts D, F, and other applicable subparts of 29 CFR 1926.

The Welding and Cutting Standard, 29 CFR 1926 Subpart J, does not call for employees to receive training on the health hazards of welding-related fumes and gases. However, 1926.353 requirements lend themselves to training. Welders should be trained to:

• Use and maintain any required air line respirators, filter-type respirators, and other PPE; and
• Properly use the appropriate ventilation system for the job.

Workers who are potentially exposed to toxic and hazardous substances (like cadmium, hexavalent chromium, and lead) specifically regulated at 29 CFR 1926 Subparts D or Z may have further training requirements.

In addition, workers whose activities are regulated by the Confined Spaces in Construction Standard, 29 CFR 1926 Subpart CC, must be provided with training so that they understand the hazards in the permit space and the methods used to isolate, control, or in other ways stay safe from these hazards.

PPE for welding and cutting

• Welding and cutting safely requires PPE that includes ear, eye, and head protection as well as flame-resistant clothing.
• Natural fibers are preferred for flame-resistant clothing because synthetics can melt and stick to skin.

It’s crucial that people doing hot work wear flame-retardant clothing and protective equipment for the eyes, ears, and head. Necessary personal protective equipment (PPE) includes the following:

• Flame-resistant aprons. These can be leather or other material that protects against radiated heat and sparks.
• Leg protection. High boots or similar protection should be worn when doing heavy work.
• Safety shoes. These should be at least ankle height because low-cut shoes may catch slag.
• Head protection. A safety helmet or other head gear should be worn to protect against sharp or falling objects.
• Ear protection. Earplugs are sufficient unless the task is very noisy (e.g., using high-velocity plasma torches), in which case earmuffs should be used.
• Eye protection. Goggles, a helmet, and a shield should be worn to provide maximum protection for the particular welding or cutting process used.
• Respiratory protection – If gases, dusts, and fumes cannot be maintained below permissible exposure levels (PELs), welders should wear respiratory protective equipment designated by the National Institute of Occupational Safety and Health (NIOSH).
• Protection during overhead work. This may include a shoulder cape or cover, a skull cap made of leather or other protective material, or another flame-resistant cap worn under a helmet.

Clothing

At 1910.252(b)(3), the Occupational Safety & Health Administration (OSHA) states, “Appropriate protective clothing required for any welding operation will vary with the size, nature and location of the work to be performed.”

This generally means long sleeves and long pants to protect from welding arc burns and welding spatter, but these are not required. Rather, this must be determined based upon the site’s hazard assessment.

With regard to flame-resistant clothing (FRC), OSHA says in a January 12, 2012, Letter of Interpretation that “if welders are exposed to flash fires or short-duration flame exposures, OSHA expects that employers would provide and ensure the use of FRC to protect workers from these hazards ... Employees wearing FRC may be exposed to hazards relating to heat stress. Therefore, employers should consider the following when selecting personal protective equipment for employees that are exposed to these adverse conditions: provide light weight breathable fabrics and allow employees to drink cold liquids, such as water and other electrolyte replenishing drinks.”

Gas-shielded arc welders should cover all parts of their bodies to protect against ultraviolet and infrared ray flash burn. Dark clothing works best to reduce reflection under the face shield.

Wool, leather, or cotton treated to reduce flammability are preferred for gas-shielded arc welding. Wool has an advantage over cotton because it resists deterioration better. Regardless of material, clothing should be:

• Thick enough to prevent flash-through burns,
• Clean,
• Free of oil or grease, and
• Buttoned at sleeves and collars.

Pants shouldn’t have cuffs or front pockets that could catch sparks.

If worn, thermal insulated underwear should be covered by other clothing and not exposed to sparks or other ignition sources. It should be down-filled or waffle weave cotton or wool. Synthetic fabrics won’t necessarily ignite more easily than cotton, but they melt as they burn, sticking tightly to skin, which can result in a very serious burn that is hard to treat and slow to heal.

Welding and cutting in confined spaces

• Welding, cutting, and brazing in confined spaces exposes workers to hazards including fire, explosion, damage to the nervous and respiratory systems, and asphyxiation.
• Atmospheric testing and monitoring is crucial because many toxins can’t be seen or smelled.

Working in confined spaces brings its own set of hazards, and performing hot work in these conditions compounds the danger. The two primary hazards of welding, cutting, or brazing in a confined space are flammable air and toxic air contaminants.

Flammable air

Fire and explosion are serious dangers in a confined space. Fumes and vapors will ignite more quickly in the trapped air. Flammable and combustible gases or vapors may be present from previous contents, tank coatings and preservatives, and welding gases.

In locations where flammable vapors may be present, precautions must be taken to prevent ignition by eliminating or controlling the source of ignition or eliminating the flammable air before working. Sources of ignition may include:

• Smoking,
• Cutting and welding,
• Hot surfaces, and
• Frictional heat.

Toxic air contaminants

Toxic air contaminants come from:

• Material previously stored in the confined space or as a result of the use of: coatings, cleaning solvents, or preservatives.
• Work that gives off a toxic gas, such as a welding operation that gives off carbon monoxide and oxides of nitrogen and ozone.

Toxic gases and vapors present two types of risk to people in a confined space:

• Irritating the respiratory or nervous system; and
• Cutting off the oxygen supply and getting into the lungs, causing asphyxiation.

Unfortunately, many toxic gases and vapors on the job cannot be smelled or seen. This means that atmospheric testing and monitoring is very important.

Generally, if a space has a hazardous atmosphere, the hazard must be eliminated or reduced by:

• Purging the hazardous atmosphere,
• Displacing the noncombustible gas,
• Flushing the hazardous atmosphere, and/or
• Ventilating with forced air.

If atmospheric hazards cannot be completely eliminated, workers must use appropriate respiratory protection and other personal protective equipment (PPE) as necessary.

Training

• Employees who will perform or support hot work must be trained in the specific hazards, procedures, and equipment involved.
• Fire watchers should receive in-depth training in recognizing and minimizing fire hazards as well as using firefighting equipment.

Several of the Occupational Safety & Health Administration’s (OSHA) welding and cutting standards require employers to train workers and specify who needs training, the frequency of training, and recordkeeping requirements. Extended classroom and hands-on training for welders and welding helpers (such as fire watchers) may be needed to meet requirements.

The table summarizes the OSHA regulations for general industry hot work training:

General content

Welding training be provided in a language that trainees understand. If a trainee’s vocabulary is limited, employers should account for that. Translators may be needed.

Trainees should be made familiar with the company welding safety program. Anyone working welding or working around welding and other hot work should know:

• The name and job title of the person responsible for safety in hot work operations;
• The company’s process for hot work permitting;
• The hazards associated with hot work: hazards from fumes and gases, radiation hazards, fire hazards, noise hazards, and electrical hazards;
• Any special procedures for the equipment being used, such as: care of compressed gas cylinders, the use of ventilation, and fire prevention methods;
• Required engineering controls, such as flash screens and fire blankets; and
• The personal protective equipment (PPE) required for the work being done.

An effective welding training program may also address:

• The types of welding used at the worksite;
• Safe operation and maintenance of welding/cutting/brazing equipment;
• Housekeeping measures;
• Inspection procedures, including for: hoses, torches, pipelines continuously employed as a ground return circuit, resistance of a ground circuit (other than by means of the structure), and ground connections;
• Testing methods for: hoses that are subject to flashback or show evidence of severe wear or damage, and determining the flammability of preservative coatings on surfaces;
• Determining when a fire watcher is required; and
• Safe work practices for welding within confined spaces.

Training for fire watchers

Fire watchers provide additional safeguards against fire during and after welding, cutting, or heating operations. Their responsibilities are addressed by OSHA in 1910.252 and by the American National Standards Institute (ANSI) in Z49.1-1967.

Training for fire watchers must include:

• Assessing whether a fire watcher is necessary,
• The specific fire hazards for that job and location,
• Checking for these hazards prior to welding or cutting,
• Covering fire hazards that can’t be moved,
• The location and operation of fire prevention and extinguishing equipment,
• The location of fire alarms, and
• Reporting fires.

Training for arc welders and cutters

OSHA requires companies to instruct employees in the safe means of arc welding and cutting. In addition to general content about hot work and the company welding safety program, employees should learn about:

• Hazards associated with arc welding, such as: radiation, fumes and gases, spatter and sparks, fire, electric shock, and noise;
• Equipment and PPE used specifically for arc welding at the site;
• Recognizing and reporting defective equipment; and
• Best practices for safeguarding unattended arc welders.

Hazards and precautions

• Hot work hazards include fire, explosion, asphyxiation, and skin and eye damage.
• Facilities can reduce these hazards by establishing “hot work zones,” providing adequate ventilation and protective equipment, and training workers in safe procedures.

Welding, cutting, and brazing pose a combination of safety and health risks to more than 500,000 workers in a wide variety of industries. The risk from fatal injuries alone is more than four deaths per thousand workers over a working lifetime.

Health hazards from welding, cutting, and brazing operations include exposures to metal fumes and to ultraviolet (UV) radiation. Safety hazards from these operations include burns, eye damage, electrical shock, cuts, and crushed toes and fingers.

These hazards can affect not only the person doing the work, but the people, materials, and structures nearby. Many of these risks can be controlled with proper work practices and personal protective equipment (PPE).

General hot work hazards

Hot work hazards vary, depending upon the facility, equipment, number of workers present, and the job at hand. Examples include:

• Damage to skin and eyes from exposure to ultraviolet and infrared rays produced by welding;
• Toxic gases, fumes, and dust that may be released during welding and cutting operations;
• Fire hazards from combustible or flammable materials, dust, vapor, or the environment; and
• Explosion hazards from lack of ventilation.

General protective measures

Many hazards of hot work can be minimized or avoided with proper equipment and practices:

• A thorough site hazard assessment allows hazards to be addressed before work begins.
• Trained fire watchers and established emergency procedures facilitate swift responses to problems.
• Designated “hot work areas” for cutting and welding can be clearly marked and thus separate these processes from others.
• Adequate ventilation can prevent fires, explosions, and toxic gas exposure.
• Respirators to protect people when ventilation and plume avoidance don’t give enough protection or when welding creates an oxygen-deficient area.
• Not getting too close to the fume or plume or weld on lead-painted surfaces.
• Using appropriate PPE, including:
  • Flame-resistant aprons,
  • Leggings and high boots,
  • Ankle-length safety shoes worn under pant legs,
  • Shoulder capes and skull caps,
  • Earplugs or earmuffs,
  • Insulated gloves,
  • Safety helmets,
  • Goggles,
  • Shields, and
  • American National Standards Institute (ANSI)–approved filter lenses and plates.
• Wearing wool, leather, and treated cotton clothing to help make workers less flammable.

Ventilation

• Due to the fumes, gases, and dusts involved in hot work, ventilation is an important part of performing this work.
• The primary tools used for ventilation are fans and exhaust systems, but respirators may be required in some circumstances, especially in confined spaces.

Welders can be exposed to a number of fumes, gases, and dusts. These contaminants can harm the health of workers and/or accumulate to the point of causing a fire. Ventilation helps to reduce the concentration of contaminants and prevent the accumulation of flammable gases, vapors, and dusts.

According to the Occupational Safety & Health Administration (OSHA), whenever and wherever welding occurs, everyone involved in the operation must be aware of welding fumes and gases and take necessary, especially ventilation, precautions. Even in metal cutting jobs that are considered routine, established safety procedures should always be followed.

Welding ventilation techniques vary. Often, however, a relatively simple ventilation method like the appropriate use of fans will be all that is required to provide good ventilation during hot work.

OSHA specifies in 1910.252(c) that if mechanical ventilation is used, it must consist of either:

• General mechanical ventilation, or
• A local exhaust system.

Related regulations

OSHA and the American National Standards Institute (ANSI) both have standards that can be relevant to ventilation during hot work:

• 29 CFR 1910, Subpart Q — Welding, Cutting and Brazing.
• 29 CFR 1926.55 — Gases, vapors, fumes, dusts, and mists.
• 29 CFR 1926.59 — Hazard communication.
• 29 CFR 1910.1200 — Hazard communication.
• 29 CFR 1926.103 — Respiratory protection.
• 29 CFR 1926 Subpart J — Welding and cutting.
• 29 CFR 1926.1126 — Chromium (VI).
• 29 CFR 1926.1127 — Cadmium.
• ANSI Z49.1-1967 — Safety in Welding and Cutting.
• 29 CFR 1910.252 — General Requirements.

Types of ventilation

Ventilation can be provided by a general mechanical or local exhaust system. Open spaces can also help to reduce accumulations.

General mechanical ventilation lowers contamination levels by using fans of various types to dilute the contaminated air with fresh air. OSHA requires mechanical ventilation to be provided when welding or cutting is done in certain circumstances on most metals, with some exceptions (including zinc, lead, cadmium, beryllium, and mercury) that have more specific requirements. Mechanical ventilation is required when welding is performed:

• In a space of less than 10,000 cubic feet per welder;
• In a room with a ceiling height of less than 16 feet; or
• In confined spaces or where partitions, balconies, or other structural barriers significantly obstruct cross ventilation.

Outside of these conditions, natural ventilation is considered sufficient.

Local exhaust systems remove fumes and smoke at the source using either of the following:

• A hood. This is movable so that the welder can place it as close as possible to the work. It must be able to maintain a minimum airflow of 100 feet/minute toward the hood.
• A fixed enclosure. This is a booth with a top and at least two sides surrounding the welding or cutting operation. It must be able to maintain a minimum airflow of 100 feet/minute away from the welder.

The need for local exhaust ventilation for welding or cutting outside of confined spaces depends on the individual circumstances. However, it is recommended for fixed-location production welding and for all production welding on stainless steels.

Ventilation in confined spaces

All welding and cutting operations in confined spaces must be adequately ventilated to prevent toxic material accumulation or oxygen deficiency. Only clean, breathable air can be used to replace air withdrawn from the confined space.

If it’s not possible to provide adequate ventilation, workers must use airline respirators or hose masks approved by the National Institute for Occupational Safety and Health (NIOSH).

Fumes and gases

• Hot work can expose workers to many types of fumes and gases, with a corresponding array of health hazards.
• Preventing and avoiding these health hazards depends on the work circumstances, including materials, location, equipment, and practices.

The many hazards associated with welding operations include exposure to several types of air contaminants: metal fumes, gas byproducts, and shielding gases. These contaminants can harm workers’ health. Fortunately, there are ways to reduce or eliminate them.

Related regulations

The Occupational Safety & Health Administration (OSHA)) and the American National Standards Institute (ANSI) both have standards that can be relevant to fumes and gases encountered during hot work:

• 29 CFR 1910 Subpart Q — Welding, Cutting and Brazing.
• 29 CFR 1910.1200 — Hazard communication.
• 29 CFR 1926.55 — Gases, vapors, fumes, dusts, and mists.
• 29 CFR 1926.59 — Hazard communication.
• 29 CFR 1926.103 — Respiratory protection.
• 29 CFR 1926 Subpart J — Welding and cutting.
• 29 CFR 1926.1126 — Chromium (VI).
• 29 CFR 1926.1127 — Cadmium.
• ANSI Z49.1-1967 — Safety in Welding and Cutting.

Types of fumes and gases

During welding and cutting operations, metal fumes may be released, gas byproducts may be formed, and shielding gases used during the process may escape into the air.

Metal fumes produced during hot work depend on the circumstances of the operation —the metal, metal preservatives, electrode, or filler rod used. Some common welding fumes that can have negative health effects include: barium, beryllium, cadmium, chromium, copper, fluoride, iron, lead, magnesium, manganese, and zinc.

Gases are also released during welding operations. These gases can form in many ways. Carbon monoxide, for example, can form when carbon dioxide shielding gas is used in gas metal arc welding. Gas byproducts formed during welding may include: nitric oxide, nitrogen dioxide, carbon monoxide, ozone, phosgene, hydrogen, fluoride, and carbon dioxide.

Certain other gases are not byproducts but used as shielding gases supplied during the welding process, including: argon, helium, nitrogen, and carbon dioxide.

Health effects

Fume and gas exposure can cause an array of health effects, both short- and long-term. Acute exposure to welding fumes and gases can result in eye, nose, and throat irritation; dizziness; and nausea. Workers should be alert for these symptoms and leave the area if any develop. Prolonged exposure to welding fumes may cause lung damage and various types of cancer, including lung, larynx, and urinary tract.

Depending on the fume or gas, health effects may also include metal fume fever, stomach ulcers, kidney damage, and nervous system damage. For example, prolonged exposure to manganese fumes can cause Parkinson’s-like symptoms.

Some gases, such as helium, argon, and carbon dioxide, displace oxygen in the air. This can lead to suffocation, particularly during welding in enclosed spaces. Carbon monoxide gas can form, posing an asphyxiation hazard.

Factors affecting exposure

Factors that affect exposure to welding fumes or gases depend on a number of circumstances:

• Type of welding process,
• Welder’s work practices,
• Base metal and filler metals used,
• Composition of the welding rod,
• Location (outside or in an enclosed space), and
• Air movement and ventilation.

Minimizing health hazards from fumes and gases

While there are a lot of health hazards associated with fumes and gases from hot work, there are also many ways to control or eliminate them.

Before welding begins, some hazards can be prevented by:

• Performing atmospheric tests,
• Cleaning welding surfaces of any coating that could create a toxic exposure,
• Understanding the risks and symptoms associated with the materials to be used, and
• Substituting a lower fume-generating or less toxic welding type or consumable (when feasible).

Workers can reduce their risks with safety equipment, including:

• Using local exhaust systems to remove fumes and gases from workers’ breathing zone,
• Keeping fume hoods and vacuum nozzles close to the plume source, and
• Wearing respiratory protection if ventilation does not reduce fumes and gases to safe levels.

Workers can also reduce their risks with their work practices, including:

• Positioning themselves upwind to avoid breathing welding fumes and gases,
• Using the movement of fresh air to reduce fume and gas levels in the work area,
• Not getting too close to the fume or gas plume, and
• Knowing the symptoms of overexposure to fumes and gases and getting out of the area if they develop.

Equipment

• Welding hoses, manifolds, torches, regulators, gauges, and curtains are all regulated to some extent by OSHA.

Welding involves many types of equipment, some of which the Occupational Safety & Health Administration (OSHA) regulates specifically and some it does not. Some examples are discussed below.

Welding hoses

Employers should check with the manufacturer of hoses and gauges to see what restrictions or cautions are noted, or to see how lines should be purged after turning off the gases.

Fuel gas and oxygen hoses must be easily distinguishable from each other, either with color contrast or surface characteristics that are noticeable to the touch.

All hoses carrying acetylene, oxygen, natural/manufactured gas, or any ignitable or combustible gas or substance must be inspected at the beginning of each work shift. Defective hoses must be removed from service.

No specific regulation addresses storage of welding hoses. If there is a known hazard, OSHA would expect that an employer address it under their General Duty Clause obligations.

Fuel gas and oxygen manifolds

Fuel gas and oxygen manifolds must bear the name of the substance they contain in letters at least 1 inch high. The letters must be either painted on the manifold or a sign permanently attached to it.

Hose connections must be kept free of grease and oil and be capped when not in use.

Torches

Torches must be inspected for leaks at the beginning of each work shift, and defective torches removed from service.

Torches should never be lit using matches or from hot work.

If torch tip holes become clogged, they should be cleaned with suitable cleaning wires, drills, or other devices designed for this purpose.

Regulators and gauges

Oxygen and fuel gas pressure regulators, including related gauges, must be inspected to verify that they are in good working order.

Curtains/booths

OSHA prefers that welding be shielded from other operations when possible, using weld curtains or booths.

At 1910.252(b)(2)(iii), OSHA states, “Where the work permits, the welder should be enclosed in an individual booth painted with a finish of low reflectivity such as zinc oxide (an important factor for absorbing ultraviolet radiations) and lamp black, or shall be enclosed with non-combustible screens similarly painted.” Passersby should be separated from welding using these curtains, booths, or screens, or else should wear suitable eye protection.

Arc welding precautions

• Arc welding comes with an array of hazards but can be fairly safe with proper precautions and work practices, particularly electrical safety procedures.

Gas fumes, radiation, and electric shock are some of the hazards involved in arc welding. A welding arc emits blinding light and is hot enough to melt steel. It generates toxic fumes that are composed of microscopic particles of molten metal. Sparks and molten slag thrown by the arc can fly up to 35 feet and can cause fires and explosions.

Despite all these hazards, arc welding can be safe with proper precautions and work practices. Arc welders can protect themselves and others in several ways:

• Using safety gear:
  • Wearing personal protective equipment (PPE), including respirators and eye protection as required;
  • Using ventilation to reduce concentrations of hazardous fumes, gases, and dusts; and
  • Covering all parts of the body to protect against ultraviolet and infrared ray flash burn. Flame-retardant clothing is important. Dark clothing works best to reduce reflection under the face shield. Note that woolen clothing resists deterioration better than cotton.
• Following safety procedures:
  • Having a fire watcher while welding;
  • Knowing confined space welding procedures and checking for hazardous atmospheres and toxic materials, in accordance with the employer’s permit-required confined space program;
  • Being aware of coworkers and protecting them from falling sparks and slag; and
  • Using shielding to keep passersby from looking at the arc radiation or being injured by flying slag.
• Taking electrical precautions:
  • Properly grounding, installing, and operating the equipment;
  • Checking for and reporting defective equipment;
  • Avoiding damp surfaces or clothing while arc welding;
  • Using only well-insulated, intact electrode holders, cables, and connectors;
  • Staying insulated from the work, including with dry gloves and rubber-soled shoes;
  • Not dipping hot electrode holders in water;
  • Removing electrodes from electrode holders before leaving them unattended;
  • Opening the power supply switch to the equipment before stopping work or moving the arc welding or cutting machine; and
  • Having a disconnecting means in the supply circuit for each arc welder not equipped with its own disconnect.

Gas welding precautions

• Gas welding poses a variety of health hazards due to its association with fumes, gases, and ionizing radiation.
• Proper storage and handling of compressed gas cylinders is crucial for preventing fires and explosions.

Fumes, gases, and ionizing radiation formed or released when welding, cutting, or brazing are associated with numerous health hazards, including:

• Heavy metal poisoning,
• Lung cancer,
• Metal fume fever, and
• Flash burns.

The risks vary depending on the welding materials used and surfaces welded. The presence of oil or grease is one potential source of fire danger for gas welders. This danger can be reduced by:

• Keeping oxygen cylinders and fittings cylinder caps and valves, couplings, regulators, hose, and apparatus free from oil or greasy substances; and
• Not handling cylinders or fittings with oily/greasy hands or gloves.

Safe handling of compressed gas cylinders

Handling compressed gas cylinders safely is crucial in preventing fires and explosions. Cylinders must be stored under the proper conditions:

• Secured in an upright position at all times (except for short periods of transportation, if necessary);
• In a definitely assigned location that is:
  • Well-protected, well-ventilated, and dry;
  • At least 20 feet from highly combustible materials such as oil or excelsior;
  • Away from radiators and other sources of heat;
  • Away from elevators, stairs, and gangways; and
  • Not in danger of damage from passing or falling objects, or tampering by unauthorized people.

Cylinders must be kept far enough away from a welding or cutting project so that sparks, hot slag, or flames do not reach them. When this is impractical, fire shields must be used.

Valve protection caps must be in place, hand-tight, except when cylinders are in use or connected for use. Before a regulator is connected to the cylinder valve, the valve must be cracked (opened slightly and closed immediately). This clears the valve of dust or dirt that could enter the regulator.

Fire prevention

• Appropriate fire prevention procedures depend on the nature of the object to be welded or cut and its surroundings.

Welding and metal cutting operations produce molten metal, sparks, weld spatter, slag, and hot work surfaces. All of these can create a situation that can cause fires. At 1910.252, the Occupational Safety & Health Administration (OSHA) addresses the fire hazards of hot work.

More information can be found in:

• The company fire prevention plan.
• 29 CFR 1910, Subpart Q — Welding, cutting and brazing.
• ANSI Z49.1-1967 — Safety in Welding and Cutting.

To best prevent and address fires, workers must be well-informed about:

• The company’s welding “best practices,”
• The need to check for fire hazards prior to welding or cutting,
• How to obtain a “hot work” permit, and
• How to report fires.

They should also know when and how to involve a fire watcher.

When are fire watchers required?

Fire watchers provide additional safeguards against fire during and after welding, cutting, or heating operations. A fire watcher is required in situations where:

• Other than a minor fire might develop,
• Combustible material is located within 35 feet of the work,
• Combustible material is located more than 35 feet away but can be easily ignited by sparks,
• Wall or floor openings within 35 feet expose combustible material in adjacent areas or concealed wall or floor spaces, or
• Combustible materials are located on the opposite side of surfaces being welded.

The fire watch is to be maintained for at least 30 minutes following completion of the work.

Compressed gases

• OSHA, CGA, and the DOT all have regulations for dealing with the special hazards associated with compressed gases in cylinders.
• In general, compressed gas cylinders must be handled gently, kept away from temperature extremes and electricity, and closed when not in use.

Compressed gases in cylinders present special hazards that include the possibility of oxygen displacement and toxic effects from the gas itself, as well as fire and explosion risks due to the high pressure. Thus, gas cylinders may only be handled and used by trained workers.

The Occupational Safety & Health Administration (OSHA) addresses compressed gases in general at 1910.101, which adopts by reference some regulations from the Compressed Gas Association (CGA).

Marking gas cylinders

Cylinders, containers, pipes, etc., must be clearly marked so that the gas can be easily identified. Labels should not be defaced or removed. Containers whose content labels are not legible should be returned unused to the supplier. Containers should not be repainted, and container color should not be used to identify the cylinder content.

All gas lines leading from a compressed gas supply should be clearly labeled or identified. Some states require specific labeling of cylinders, containers, and pipes.

Inspecting gas cylinders

Employers must visually inspect compressed gas cylinders to determine that they are in safe condition under 1910.101.

Visual inspections must be conducted as prescribed in the Hazardous Materials Regulations of the Department of Transportation (49 CFR Parts 171–179 and 14 CFR Part 103) when applicable. Otherwise, they must be conducted in accordance with CGA Pamphlet C-6-1968.

In general, all parts of a cylinder (valves, neck rings, hoses, manifold, regulator, etc.) should be inspected for:

• Corrosion or pitting;
• Cracks;
• Denting or bulging;
• Gouges;
• Leaks; and
• Oil, grease, and other foreign material.

Storing gas cylinders

Proper storage of gas cylinders is crucial for maintaining a safe workplace. According to CGA P-1, storage areas must:

• Allow containers to be grouped by hazard using spacing or partitions;
• Separate full and empty containers;
• Be dry, well-drained, ventilated, and fire-resistant;
• Not exceed 125°F; and
• Not expose the cylinders to tampering by unauthorized persons.

Containers must be:

• Wearing their valve protection caps (if provided);
• Adequately separated from corrosive chemicals or fumes, readily ignitable substances, and combustibles;
• Stored on well-drained, paved surfaces to prevent bottom corrosion/rusting;
• Clear of walkways, elevators, stairs, unprotected platform edges, and possible falling objects;
• Protected from cuts, punctures, and other abrasions; and
• Secured with brackets, chains, or straps.

Moving gas cylinders

Safe handling of gas cylinders includes moving them carefully, both within and between facilities.

Practices to avoid include:

• Dragging or sliding cylinders,
• Lifting cylinders by their caps,
• Using lifting magnets, and
• Using cylinders (full or empty) as rollers or supports.

Protective caps and outlet caps or plugs should be replaced before empty cylinders are returned to the supplier.

OSHA states that compressed gas cylinders that are not secured to a “special truck” must have their regulators removed and valve-protection caps installed. A special truck is a vehicle or cart that provides stable support of vertical standing Department of Transportation portable gas cylinders during movement and at various work locations. It must include protection of cylinder valves and regulators. CGA Pamphlet P-1 allows for a “suitable hand truck, forklift truck, or similar material handling device,” as long as cylinders are properly secured to it by a chain or other comparable method.

Using gas cylinders

When using any compressed gas (i.e., cylinders, portable tanks, rail tank cars, or motor vehicle cargo tanks), employers must comply with the provisions outlined in CGA Pamphlet P-1-1965, which is incorporated by reference in the OSHA standard.

When handling compressed gas cylinders, workers should always follow these procedures:

• General handling:
  • Do not subject cylinders to artificially low temperatures or temperatures above 125°F.
  • Keep cylinders away from heat sources and flames.
  • Keep cylinders away from places where they could become part of an electric current, and never use them as a ground.
  • Never drop cylinders or strike them against one another or other surfaces.
  • Never attempt to transfer compressed gases from one container to another. (This must only be performed by the gas supplier or by personnel familiar with the hazards.)
  • Keep cylinders far enough away from welding or cutting projects so that sparks, hot slag, or flames do not reach them. When this is impractical, use fire shields.
• Valves:
  • Never tamper with or alter cylinders, valves, or safety-related devices.
  • Leave valve protection caps in place and hand-tightened until cylinders are secured and ready to be connected.
  • For gas cylinders with valve outlet caps and plugs that form a gas-tight seal, keep these devices on the valve except when containers are secured and connected.
  • Keep cylinder valves closed except when the cylinder is being used.
  • When opening a valve, stand to one side of the regulator and open it slowly.
  • Do not tighten connections or leaking fittings or attempt other repairs while the system is under pressure.
  • Before connecting a regulator to the cylinder valve, open the valve slightly for an instant and then close it.
  • Do not use oxygen from a cylinder without first attaching an oxygen regulator to the cylinder valve, unless the cylinder is connected to a manifold.

Acetylene, hexavalent chromium, and cadmium

• Acetylene poses a flammability hazard and must be used, transported, and stored properly to keep workers safe.
• Hexavalent chromium is highly toxic and can damage the eyes, skin, nose, throat, and lungs and cause cancer.
• Cadmium exposure can cause irritation, stomach problems, lung damage, and kidney disease.

Several substances that welders may encounter are regulated individually because of their specific hazards. These include acetylene, hexavalent chromium, and cadmium.

Acetylene

Acetylene is a colorless gas that has many industrial uses, from being a raw material to use in welding. It poses a flammability hazard and must be used, transported, and stored properly.

The Occupational Safety & Health Administration (OSHA) requirements apply to employers who have employees who use or are exposed to acetylene. The specific requirements vary depending on the application.

Relevant citations:

• 1910.102— Acetylene.
• Related regulation: 1910.253 — Oxygen-fuel gas welding and cutting.
• Compressed Gas Association (CGA) Pamphlet G-1-2009.
• National Fire Protection Association (NFPA) 51A-2006 — “Standard for Acetylene Charging Plants.”
• NFPA 51A-2001 — “Standard for Acetylene Charging Plants.”

To comply with requirements and provide a safe workplace, employers must:

• Ensure cylinder safety. Employers must follow the provisions of CGA Pamphlet G-1-2009 for all in-plant transfer, handling, storage, and use of acetylene.
• Store cylinders valve end up, according to OSHA 1910.253.
• Keep piped systems safe. Piped systems installed before Feb. 16, 2006, must comply with Chapter 9 of NFPA 51A-2006. Older systems may instead comply with Chapter 7 of NFPA 51A-2001.
• Ensure that facilities, equipment, structures, and installations used to generate acetylene or charge acetylene cylinders comply with NFPA 51A-2006 or 51A-2001, as above.
• Communicate hazard information through a hazard communication program.
• Ensure cylinders are properly marked.

Hexavalent chromium

Chromium hexavalent (Cr[VI]) compounds, often called hexavalent chromium, may be created during hot work such as welding on stainless steel or melting chromium metal. The high temperatures involved in the process result in oxidation that converts chromium to a hexavalent state.

Hexavalent chromium can pose a serious hazard to workers. Chromium is converted to its hexavalent state, Cr(VI), during the welding process, and Cr(VI) fume is highly toxic and can damage the eyes, skin, nose, throat, and lungs and cause cancer. OSHA regulates worker exposure to Cr(VI) under 1926.1126, which has a permissible exposure limit (PEL) of 5 μg/m 3 as an eight-hour average.

Cadmium

The Agency for Toxic Substances and Disease Registry estimates that about 300,000 workers in the U.S. face exposure to cadmium each year. Cadmium exposure can threaten workers who perform activities like the following without wearing some type of personal protection:

• Cutting, grinding, or welding on surfaces painted with cadmium-containing paints; or
• Wrecking, demolishing, and salvaging structures where cadmium is present; or
• Transporting, storing, and disposing of cadmium or cadmium-containing materials on site.

OSHA has set the PEL for cadmium in work area air at 5 micrograms per cubic meter of air (5 μg/m3) for an 8-hour workday.

Cadmium exposure may occur in several ways:

Hot work and fire watchers in construction

• 29 CFR 1926.352 specifies circumstances in which fire watchers are needed on construction sites, as well as their training and responsibilities.

Welding and metal cutting operations produce molten metal, sparks, weld spatter, slag, and hot work surfaces. All of these can create a situation that can cause fires.

29 CFR 1926.352 is concerned with fire hazards in situations where:

• Other than a minor fire might develop,
• Combustible material is located within 35 feet of the work,
• Combustible material is located more than 35 feet away but can be easily ignited by sparks,
• Wall or floor openings within 35 feet expose combustible material in adjacent areas or concealed wall or floor spaces, or
• Combustible materials are located on the opposite side of surfaces being welded.

Where to go for more information:

• The company fire prevention plan.
• 29 CFR 1926 Subpart J — Welding and cutting.
• ANSI Z49.1-1967 — Safety in Welding and Cutting.

Fire watchers in construction

According to 1926.352, construction employees assigned to guard against fire during welding, cutting, or heating operations (and for a sufficient time after completion of the work) are to be instructed on the specific anticipated fire hazards and how the provided firefighting equipment is to be used.

Fire watchers are additional personnel who:

• Provide additional safeguards against fire during and after the welding, cutting, or heating operations;
• Are trained on the specific fire hazards for that job and location; and
• Know where fire prevention equipment is located and how to use it.

The fire watch is to be maintained for at least 30 minutes following completion of the work.

Fire watchers must be trained in:

• Assessing whether a fire watcher is necessary,
• The responsibilities of the fire watcher,
• The company’s welding best practices,
• Checking for fire hazards prior to welding or cutting,
• Covering fire hazards that cannot be moved,
• Obtaining a hot work permit, and
• Reporting fires.

Gas welding and cutting

Welding is classified into two groups: fusion (heat alone) or pressure (heat and pressure) welding. There are three types of fusion welding: electric arc, gas, and thermit. Electric arc welding is the most widely used type of fusion welding. It employs an electric arc to melt the base and filler metals.

Gas or oxy-fuel welding uses a flame from burning a 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. Thermit welding uses a chemical reaction to produce intense heat instead of using gas fuel or electric current. Pressure welding uses heat along with impact-type pressure to join the pieces.

Oxy-fuel and plasma cutting, along with brazing, are related to welding as they all involve the melting of metal and the generation of airborne metal fume. Brazing is a metal-joining process where only the filler metal is melted.

Arc welding and cutting

Manual electrode holders

Employers must:

• Use only manual electrode holders which are specifically designed for arc welding and cutting, and capable of safely handling the maximum rated current.
• Verify any current-carrying parts passing through the portion of the holder which the arc welder or cutter grips in his hand, and the outer surfaces of the jaws of the holder, are fully insulated against the maximum voltage encountered to ground.

Welding cables and connectors

Employers must:

• Make sure all arc welding and cutting cables are:
  • The completely-insulated, flexible type; and
  • Capable of handling to maximum current requirements of the work in progress, taking into account the duty cycle under which the arc welder or cutter is working.
• Use only cables free from repair or splices for a minimum distance of 10 feet from the cable end to which the electrode holder is connected, except that cables with standard insulated connectors or with splices whose insulating quality is equal to that of the cable are permitted.
• Cable in need of repair must not be used. When a cable, other than the cable lead referred to in the previous paragraph, becomes worn to the extent of exposing bare conductors, protect the exposed portion by rubber and friction tape or other equivalent insulation.
• When it becomes necessary to connect or splice lengths of cable one to another, use substantial insulated connectors of a capacity at least equivalent to that of the cable. If connected by cable lugs, securely fasten them together to give good electrical contact and make sure the exposed metal parts of the lugs are completely insulated.

Fire prevention

Employers must:

• Move (when practical) objects to be welded, cut, or heated to a designated safe location. If these objects cannot by readily moved, take all movable fire hazards in the vicinity to a safe place, or otherwise protected. If these objects cannot be moved and if all the fire hazards cannot be removed, take positive means to confine the heat, sparks, and slag, and to protect the immovable fire hazards from them.
• Welding, cutting, or heating is not to be done where the application of flammable paints, or the presence of other flammable compounds, or heavy dust concentrations creates a hazard.
• Provide suitable fire extinguishing equipment so it is immediately available in the work area and be ready for instant use.
• If normal fire prevention precautions are not sufficient, assign additional personnel to guard against fire:
  • While the actual welding, cutting, or heating operation is being performed; and
  • For a sufficient period of time after completion of the work to ensure that no possibility of fire exists.
• Instruct personnel as to the specific anticipated fire hazards and how the firefighting equipment provided is to be used.
• When welding, cutting, or heating is performed on walls, floors, and ceilings, since direct penetration of sparks or heat transfer may introduce a fire hazard to an adjacent area, the same precautions shall be taken on the opposite side as are taken on the side on which the welding is being performed.
• For the elimination of possible fire in enclosed spaces as a result of gas escaping through leaking or improperly closed torch valves, shut off the gas supply to the torch at some point outside the enclosed space whenever the torch is:
  • Not to be used, or
  • Left unattended for a substantial period of time.
• Overnight and at the change of shifts, remove the torch and hose from the confined space.
• Remove open-end fuel gas and oxygen hoses from enclosed spaces when they are disconnected from the torch or other gas-consuming device.
• Keep drums, pails, and other containers which contain flammable liquids closed, except when the contents are being removed or transferred. Move empty containers to a safe area apart from hot work operations or open flames.
• Drums, containers, or hollow structures which have contained toxic or flammable substances must (before welding, cutting, or heating is undertaken on them) either be filled with water or thoroughly cleaned of such substances and ventilated and tested.
• Before heat is applied to a drum, container, or hollow structure, provide a vent or opening for the release of any built-up pressure during the application of heat.

Ventilation and protection in welding, cutting, and heating

Welding health hazards

Chemical agents

Zinc

Zinc is used in large quantities in the manufacture of brass, galvanized metals, and various other alloys. Inhalation of zinc oxide fumes can occur when welding or cutting on zinc-coated metals. Exposure to these fumes is known to cause metal fume fever. Symptoms of metal fume fever are very similar to those of common influenza. They include fever (rarely exceeding 102°F), chills, nausea, dryness of the throat, cough, fatigue, and general weakness and aching of the head and body. The victim may sweat profusely for a few hours, after which the body temperature begins to return to normal. The symptoms of metal fume fever have rarely, if ever, lasted beyond 24 hours.

Cadmium

Cadmium is used frequently as a rust-preventive coating on steel and also as an alloying element. Acute exposures to high concentrations of cadmium fumes can produce severe lung irritation, pulmonary edema, and in some cases, death. Long-term exposure to low levels of cadmium in air can result in emphysema (a disease affecting the ability of the lung to absorb oxygen) and can damage the kidneys.

Beryllium

Beryllium is sometimes used as an alloying element with copper and other base metals. Acute exposure to high concentrations of beryllium can result in chemical pneumonia. Long-term exposure can result in shortness of breath, chronic cough, and significant weight loss, accompanied by fatigue and general weakness.

Iron oxide

Iron is the principal alloying element in steel manufacture. During the welding process, iron oxide fumes arise from both the base metal and the electrode. The primary acute effect of this exposure is irritation of nasal passages, throat, and lungs. Although long-term exposure to iron oxide fumes may result in iron pigmentation of the lungs, most authorities agree that these iron deposits are not dangerous.

Mercury

Mercury compounds are used to coat metals to prevent rust or inhibit foliage growth (marine paints). Under the intense heat of the arc or gas flame, mercury vapors will be produced. Exposure to these vapors may produce stomach pain, diarrhea, kidney damage, or respiratory failure. Long-term exposure may produce tremors, emotional instability, and hearing damage.

Lead

The welding and cutting of lead-bearing alloys or metals whose surfaces have been painted with lead-based paint can generate lead oxide fumes. Inhalation and ingestion of lead oxide fumes and other lead compounds will cause lead poisoning. Symptoms include metallic taste in the mouth, loss of appetite, nausea, abdominal cramps, and insomnia. In time, anemia and general weakness, chiefly in the muscles of the wrists, develop. Lead adversely affects the brain, central nervous system, circulatory system, reproductive system, kidneys, and muscles.

Fluorides

Fluoride compounds are found in the coatings of several types of fluxes used in welding. Exposure to these fluxes may irritate the eyes, nose, and throat. Repeated exposure to high concentrations of fluorides in air over a long period may cause pulmonary edema (fluid in the lungs) and bone damage. Exposure to fluoride dusts and fumes has also produced skin rashes.

Chlorinated hydrocarbon solvents

Various chlorinated hydrocarbons are used in degreasing or other cleaning operations. The vapors of these solvents are a concern in welding and cutting because the heat and ultraviolet radiation from the arc will decompose the vapors and form highly toxic and irritating phosgene gas. (See Phosgene.) Phosgene Phosgene is formed by decomposition of chlorinated hydrocarbon solvents by ultraviolet radiation. It reacts with moisture in the lungs to produce hydrogen chloride, which in turn destroys lung tissue. For this reason, any use of chlorinated solvents should be well away from welding operations or any operation in which ultraviolet radiation or intense heat is generated.

Carbon monoxide

Carbon monoxide is a gas usually formed by the incomplete combustion of various fuels. Welding and cutting may produce significant amounts of carbon monoxide. In addition, welding operations that use carbon dioxide as the inert gas shield may produce hazardous concentrations of carbon monoxide in poorly ventilated areas. This is caused by a “breakdown” of shielding gas. Carbon monoxide is odorless and colorless and cannot be detected. Common symptoms of overexposure include pounding of the heart, a dull headache, flashes before the eyes, dizziness, ringing in the ears, and nausea.

Nitrogen oxides

The ultraviolet light of the arc can produce nitrogen oxides (NO, NO2), from the nitrogen (N) and oxygen (O2) in the air. Nitrogen oxides are produced by gas metal arc welding (GMAW or short-arc), gas tungsten arc welding (GTAW or heli-arc), and plasma arc cutting. Even greater quantities are formed if the shielding gas contains nitrogen. Nitrogen dioxide (NO2), one of the oxides formed, has the greatest health effect. This gas is irritating to the eyes, nose, and throat but dangerous concentrations can be inhaled without any immediate discomfort. High concentrations can cause shortness of breath, chest pain, and fluid in the lungs (pulmonary edema).

Ozone

Ozone (O3) is produced by ultraviolet light from the welding arc. Ozone is produced in greater quantities by gas metal arc welding (GMAW or short-arc), gas tungsten arc welding (GTAW or heli-arc), and plasma arc cutting. Ozone is a highly active form of oxygen and can cause great irritation to all mucous membranes. Symptoms of ozone exposure include headache, chest pain, and dryness of the upper respiratory tract. Excessive exposure can cause fluid in the lungs (pulmonary edema). Both nitrogen dioxide and ozone are thought to have long-term effects on the lungs.

Welding physical hazards

Environmental agents

Ultraviolet radiation

Ultraviolet radiation (UV) is generated by the electric arc in the welding process. Skin exposure to UV can result in severe burns, in many cases without prior warning. UV radiation can also damage the lens of the eye. Many arc welders are aware of the condition known as “arc-eye,” a sensation of sand in the eyes. This condition is caused by excessive eye exposure to UV. Ultraviolet rays also increase the skin effects of some industrial chemicals (coal tar and cresol compounds, for example).

Infrared radiation

Exposure to infrared radiation (IR), produced by the electric arc and other flame cutting equipment may heat the skin surface and the tissues immediately below the surface. Except for this effect, which can progress to thermal burns in some situations, infrared radiation is not dangerous to welders. Most welders protect themselves from IR (and UV) with a welder’s helmet (or glasses) and protective clothing.

Intense visible light

Exposure of the human eye to intense visible light can produce adaptation, pupillary reflex, and shading of the eyes. Such actions are protective mechanisms to prevent excessive light from being focused on the retina. In the arc welding process, eye exposure to intense visible light is prevented for the most part by the welder’s helmet. However, some individuals have sustained retinal damage due to careless “viewing” of the arc. At no time should the arc be observed without eye protection.

Transporting, moving, and storing compressed gas cylinders

Employers must:

• Secure valve protection caps in place.
• Secure hoisted cylinders on a cradle, slingboard, or pallet. They must not be hoisted or transported by means of magnets or choker slings.
• Move cylinders by tilting and rolling them on their bottom edges. They must not be intentionally dropped, struck, or permitted to strike each other violently.
• When cylinders are transported by powered vehicles, secure them in a vertical position.
• Valve protection caps must not be used for lifting cylinders from one vertical position to another. Never use bars under valves or valve protection caps to pry cylinders loose when frozen. Use warm, not boiling, water to thaw cylinders loose.
• Unless cylinders are firmly secured on a special carrier intended for this purpose, regulators must be removed and valve protection caps put in place before cylinders are moved.
• Use a suitable cylinder truck, chain, or other steadying device to keep cylinders from being knocked over while in use.
• Close the cylinder valve when work is finished, when cylinders are empty, or when cylinders are moved.
• Secure compressed gas cylinders in an upright position at all times, except (if necessary) for short periods of time while cylinders are actually being hoisted or carried.
• Separate oxygen cylinders in storage from fuel-gas cylinders or combustible materials (especially oil or grease), a minimum distance of 20 feet or by a noncombustible barrier at least 5 feet high having a fire-resistance rating of at least one-half hour.
• Inside of buildings, store cylinders a well-protected, well-ventilated, dry location, at least 20 feet from highly combustible materials such as oil or excelsior. Cylinders should be stored in definitely assigned places away from elevators, stairs, or gangways. Assigned storage places must be located where cylinders will not be knocked over or damaged by passing or falling objects, or subject to tampering.
• The in-plant handling, storage, and utilization of all compressed gases in cylinders, portable tanks, rail tank cars, or motor vehicle cargo tanks must be in accordance with Compressed Gas Association Pamphlet P-1-1965.

Using cylinders during work

Employers must:

• Keep cylinders far enough away from the actual welding or cutting operation so that sparks, hot slag, or flame will not reach them. When this is impractical, fire-resistant shields must be provided.
• Place cylinders where they cannot become part of an electrical circuit. Do not strike electrodes against a cylinder to strike an arc.
• Place fuel gas cylinders with the valve end up whenever they are in use. Do not put them in a location where they would be subject to open flame, hot metal, or other sources of artificial heat.

Treatment of cylinders

• Cylinders, whether full or empty, must not be used as rollers or supports.
• Only the gas supplier must attempt to mix gases in a cylinder.
• Only the owner of the cylinder, or a person authorized by him, can refill a cylinder.
• Never use a cylinder’s contents for purposes than those intended by the supplier.
• All cylinders used must meet the Department of Transportation requirements published in 49 CFR Part 178, Subpart C, Specification for Cylinders .
• Do not use damaged or defective cylinders.

Use of fuel gas

Instruct employees in the safe use of fuel gas, as follows:

• Do not use fuel gas from cylinders, through torches or other devices which are equipped with shutoff valves, without reducing the pressure through a suitable regulator attached to the cylinder valve or manifold.
• Before a regulator to a cylinder valve is connected, open the valve slightly and closed immediately. (This action is generally termed “cracking” and is intended to clear the valve of dust or dirt that might otherwise enter the regulator.) The person cracking the valve shall stand to one side of the outlet, not in front of it. The valve of a fuel gas cylinder must not be cracked where the gas would reach welding work, sparks, flame, or other possible sources of ignition.
• Open the cylinder valve slowly to prevent damage to the regulator. For quick closing, do not open fuel gas cylinder valves more than 1½ turns. When a special wrench is required, it must be left in position on the stem of the valve while the cylinder is in use so that the fuel gas flow can be shut off quickly in case of an emergency. In the case of manifolded or coupled cylinders, at least one wrench must be available for immediate use. Do not place anything on top of a fuel gas cylinder in use, which may damage the safety device or interfere with the quick closing of the valve.
• Before a regulator is removed from a cylinder valve, the cylinder valve must always be closed and the gas released from the regulator.

Leaks

• If, when the valve on a fuel gas cylinder is opened, there is found to be a leak around the valve stem, close the valve and tighten the gland nut. If this action does not stop the leak, discontinue the use of the cylinder, and properly tag and remove it from the work area.
• In the event that fuel gas should leak from the cylinder valve, rather than from the valve stem (and the gas cannot be shut off), tag and remove the cylinder from the work area. If a regulator attached to a cylinder valve will effectively stop a leak through the valve seat, the cylinder need not be removed from the work area.
• If a leak should develop at a fuse plug or other safety device, remove the cylinder from the work area.

Fuel gas and oxygen manifolds

Make sure fuel gas and oxygen manifolds have the name of the substance they contain in letters at least one-inch high:

• Painted on the manifold, or
• On a sign permanently attached to the manifold.

Keep these manifolds in safe, well-ventilated, and accessible location — and not within enclosed spaces.

Make sure manifold hose connections, including both ends of the supply hose that lead to the manifold, are of the type that the hose cannot be interchanged between fuel gas and oxygen manifolds and supply header connections. Adapters must not be used to permit the interchange of hose. Keep hose connections free of grease and oil.

Cap manifold and header hose connections when not in use.

Do not allow anything to be placed on top of a manifold when in use which will damage the manifold or interfere with the quick closing of the valves.

Hoses

Fuel gas and oxygen hose must be easily distinguishable from each other. The contrast may be made by different colors or by surface characteristics readily distinguishable by the sense of touch.

Oxygen and fuel gas hoses must not be interchangeable. A single hose having more than one gas passage must not be used.

When parallel sections of oxygen and fuel gas hose are taped together, not more than four inches out of 12 inches can be covered by tape.

Inspect all hose in use at the beginning of each working shift. This includes hose carrying acetylene, oxygen, natural or manufactured fuel gas, or any gas or substance which may ignite or enter into combustion, or be in any way harmful to employees. Defective hose must be removed from service.

Hose which has been subject to flashback, or which shows evidence of severe wear or damage, must be tested to twice the normal pressure to which it is subject, but in no case less than 300 p.s.i. Defective hose, or hose in doubtful condition, must not be used.

Hose couplings must be of the type that cannot be unlocked or disconnected by means of a straight pull without rotary motion.

Boxes used for the storage of gas hose must be ventilated.

Keep hoses, cables, and other equipment clear of passageways, ladders, and stairs.

Torches

Clean clogged torch tip openings with suitable cleaning wires, drills, or other devices designed for such purpose.

Inspect torches in use at the beginning of each working shift for leaking shutoff valves, hose couplings, and tip connections. Defective torches must not be used.

Regulators and gauges

Make sure oxygen and fuel gas pressure regulators, including their related gauges, are working properly while in use.

Oil and grease hazards

Keep oxygen cylinders and fittings away from oil or grease. Cylinders, cylinder caps and valves, couplings, regulators, hose, and apparatus must be kept free from oil or greasy substances and not be handled with oily hands or gloves. Oxygen must not be directed at oily surfaces, greasy clothes, or within a fuel oil or other storage tank or vessel.