Be sure to provide adequate ventilation in all spaces in which welding is done to eliminate health hazards such as gases, fumes, and dust.
When welding or cutting on lead-bearing steels, lead-coated or cadmium-coated metals, or metal covered with paint containing lead or cadmium, you should wear an airline mask even if you are doing the work in the open air or in a well-ventilated space.
When welding or cutting is done on metals not covered in 1910.252(c)(5) through(c)(12), provide mechanical ventilation in:
Minimum rates: Ventilation must be at the minimum rate of 2,000 cubic feet (57 m (3)) per minute per welder. An exception to this requirement is when approved local exhaust hoods and booths or respirators are provided. Natural ventilation is sufficient for welding or cutting operations where the restrictions above are not present.
Local exhaust hoods and booths: Mechanical local exhaust ventilation may be either of the following:
Screens: When welding in a space entirely screened on all sides, arrange the screens so no serious restriction of ventilation exists. Mount the screens so they are about 2 feet (0.61 m) above the floor unless performing the work at so low a level that the screen is extended nearer to the floor to protect nearby workers from the glare of welding.
A confined space is generally defined as a restricted space such as a tank, boiler, pressure vessel, silo, or small compartment.
Air replacement: Provide adequate ventilation to all welding and cutting operations in confined spaces to prevent the accumulation of toxic materials or possible oxygen deficiency. The welder, helpers, and other personnel in the immediate vicinity must get adequate clean and respirable ventilation.
Airline respirators: Use NIOSH-approved airline respirators or hose masks when it is impossible to provide adequate ventilation.
Self-contained units: In areas immediately dangerous to life and health (IDLH), use one of the following:
Outside helpers: When providing welders and helpers with NIOSH-approved hose masks, either with blowers or self-contained breathing equipment, a worker must be stationed on the outside of the confined spaces to ensure the safety of those working within.
Maximum allowable concentrations: The need for local exhaust ventilation or airline respirators for welding or cutting in other than confined spaces will depend upon the individual circumstances. If air samples taken at the welding location indicate the fluorides liberated are below the maximum allowable concentration, this protection is not necessary.
Securing cylinders and machinery: Leave gas cylinders and welding machines on the outside when welding or cutting in any confined space. Securely block heavy portable mounted equipment before starting operations to prevent accidental movement.`
Lifelines: If a welder must enter a confined space through a manhole or other small opening, you must provide a way to quickly remove the welder in an emergency. In this purpose, attach safety belts and lifelines to the welder so his body cannot be jammed in a small exit opening. Place an attendant with a pre-planned rescue procedure outside to observe the welder at all times and be capable of putting rescue operations into effect.
Electrode removal: When suspending arc welding for any substantial period, such as during lunch or overnight, remove all electrodes from the holders and the holders should be carefully located so accidental contact cannot occur and the machine disconnected from the power source.
Gas cylinder shutoffs: In order to eliminate the possibility of gas escaping through leaks of improperly closed valves:
Warning signs: After completing the welding, the worker must mark the hot metal or provide some other means of warning other workers.
Torch valves: It is important to eliminate the possibility of gas escaping through leaks or improperly closed valves. If the torch will be unused for a long time (ie: overnight), close the torch valves. Shut-off the gas supply to the torch at some point outside the confined area. When necessary, remove the torch and hose from the confined space.`
The following three factors in arc and gas welding govern the amount of contamination to which welders may be exposed:
The employer must include the potentially hazardous materials in fluxes, coatings, coverings, and filler metals used in welding and cutting in the Hazard Communication Program (HCS). The employer must also include the materials released into the atmosphere during welding and cutting in the HCS. The employer must properly train and make sure each employee has access to labels on containers of such materials and safety data sheets.
Additional considerations for hazard communication in welding, cutting, and brazing include:
Welding “smoke” is composed of fine particles (fumes) and gases and can be extremely toxic. The following is a list of chemical substances that may be found in welding smoke:
|Chemical Substances in Welding Smoke|
|Other Chemicals (in fluxes, etc.)|
|Carbon dioxide||Carbon monoxide||Fluoride||Nitrogen dioxide|
|Nitric oxide||Ozone||Particulates (Other)|
|Acetaldehyde||Acrolein||Carbonyl fluoride||Dichloroacetic acid|
|Trichloroacetic acid||Formaldehyde||Hydrogen chloride||Hydrogen fluoride|
The general safety measures required while welding, cutting, and brazing include local exhaust ventilation and/or the use of airline respirators.
Provide mechanical ventilation when welding or cutting if done on metals:
Exception: If atmospheric tests under the most adverse conditions show that employee exposure to gases and fumes is within the acceptable concentrations specified by 29 CFR 1910.1000, the safety measures below are not required. See the Annotated Z Tables for more information about PELs.
Welding or cutting indoors, outdoors, or in confined spaces involving beryllium-containing base or filler metals must be done using local exhaust ventilation and airline respirators unless atmospheric tests under the most adverse conditions have established the workers' exposure is within the acceptable concentrations defined by 1910.1000. In all cases, protect all workers in the immediate vicinity of the welding or cutting operations with local exhaust ventilation or airline respirators.
In confined spaces or indoors, welding or cutting operations involving cadmium-bearing or cadmium-coated base metals should be done using local exhaust ventilation or airline respirators unless atmospheric tests under the most adverse conditions show that employee exposure is within the acceptable concentrations specified by 29 CFR 1910.1000. Welding or cutting, when done outdoors, should be done using respirators, such as fume respirators, approved for this purpose by NIOSH. Welding (brazing) involving cadmium-bearing filler metals must be done using ventilation as described in 1910.252(c)(3)or (c)(4) if the work is to be done in a confined space. For more information on Cadmium, see OSHA's Topics Page
Confined space welding can significantly increase exposure to manganese fumes. The exposure can vary considerably depending on the amount of manganese in the welding wire, rods, flux and base metal. Exposure to manganese may have serious neurological effects. Manganese poisoning or "manganism" is a disease closely related to Parkinson's disease which causes tremors, shaking, and loss of muscle control. Although the ACGIH sets the threshold limit value (TLV) at .02 milligrams per cubic meter (mg/m3) over an 8-hour work period, OSHA's PEL for manganese is 5.0 mg/m3 which is 250 times higher than the TLV. Workers' compensation carriers may require their clients to meet the TLV to reduce risk.
In confined spaces or indoors, welding or cutting operations involving metals coated with mercury-bearing materials, including paint, must be done using local exhaust ventilation or airline respirators unless atmospheric tests under the most adverse conditions show that employee exposure is within the PEL for mercury. Such operations, when done outdoors, must be done using NIOSH-approved respirators.
Confined spaces. In confined spaces, welding involving lead-base metals (erroneously called lead-burning) shall be done in accordance with 1910.252(c)(4).
Indoors. Indoors, welding involving lead-base metals shall be done in accordance with 1910.252(c)(3).
Local ventilation. In confined spaces or indoors, welding or cutting operations involving metals containing lead, other than as an impurity, or metals coated with lead-bearing materials, including paint, must be done using local exhaust ventilation or airline respirators.
Outdoors. These operations, when done outdoors, must be done using respirators approved for this purpose by NIOSH under 42 CFR part 84.
Indoors, welding or cutting involving zinc-bearing base or filler metals coated with zinc-bearing materials must be done in accordance with 1910.252(c)(3).
A fluorine compound is one that contains fluorine as an element in chemical combination, not as a free gas.
In confined spaces, welding or cutting involving fluxes, coverings, or other materials which contain fluorine compounds must be done in compliance with 1910.252(c)(4). The NIOSH (REL) and OSHA (PEL) Exposure limits for fluorine compounds the same: TWA 0.1 ppm (0.2 mg/m3).
Brazing and gas welding fluxes containing fluorine compounds must have cautionary warning labels to indicate that they contain fluorine compounds. The labels must indicate the hazards associated with fluorine compounds including eye and respiratory tract effects. One such cautionary wording recommended by the American Welding Society for brazing and gas welding fluxes reads as follows:
CAUTION--CONTAINS FLUORIDES--This flux, when heated, gives off fumes that may irritate eyes, nose, and throat.
Hexavalent chromium (Cr(VI)) is a toxic form of the element chromium and is generally man-made. Hexavalent chromium may be present in fumes generated during the production or welding of chrome alloys. Workplace exposure to Cr(VI) may cause the following health effects:
Manufacturer's instructions: In the use of cleaning materials, because of their possible toxicity or flammability, make sure to follow the appropriate precautions, such as manufacturer’s instructions.
Degreasing: Degreasing and other cleaning operations involving chlorinated hydrocarbons must be located so no vapors from these operations will reach or be drawn into the atmosphere surrounding any welding operation. In addition, keep trichloroethylene and perchloroethylene out of atmospheres penetrated by the ultraviolet radiation of gas-shielded welding operations.
Use mechanical ventilation that is adequate to remove the fumes generated by oxygen cutting when using either a chemical flux or iron powder or gas-shielded arc cutting of stainless steel.
First-aid equipment must be available at all times. Report all injuries as soon as possible for medical attention. Perform necessary first aid until medical attention is available.