Fire prevention in welding

You must remove all movable fire hazards from the vicinity to a safe place before welding or cutting. See 1910.252(a)(1)(i).

• "Movable fire hazards" means things like paper, rags, wood, flammable liquids in portable containers, or any item that can be carried away from the work area.
• If removal isn't practicable, use guards to confine sparks and heat per 1910.252(a)(1)(ii).

Guards are required when the object being welded or cut cannot be moved and combustible hazards cannot be removed; the guards must confine heat, sparks, and slag and protect immovable combustibles. See 1910.252(a)(1)(ii).

• Guards can be metal shields, curtains, or other fire-resistant barriers placed between the operation and combustibles.
• If you cannot remove combustibles or effectively guard the area, welding or cutting must not be performed per 1910.252(a)(1)(iii).

Welding or cutting must not be performed when the basic precautions in 1910.252(a)(1)(i) and 1910.252(a)(1)(ii) cannot be followed. See 1910.252(a)(1)(iii).

• That means if you cannot remove movable combustibles and cannot effectively guard against sparks, you must stop the hot work.
• Management and supervisors must enforce this restriction before authorizing work.

You must take precautions so sparks or hot particles cannot pass through floor openings, cracks, broken windows, or open doorways and ignite combustibles below or in adjacent areas. See 1910.252(a)(2)(i).

• Common measures include covering openings with fireproof material, relocating combustibles, or installing shields under the work.
• Also apply the same precautions to cracks in walls and concealed spaces that could hide flammable materials.

You must maintain suitable fire-extinguishing equipment, ready for instant use; the type depends on the combustibles exposed and may include water pails, buckets of sand, hoses, or portable extinguishers. See 1910.252(a)(2)(ii).

• Assess the hazards to choose the right extinguisher (e.g., Class A for wood/paper, Class B for flammable liquids).
• Keep equipment positioned so fire watchers and welders can access it immediately.

A fire watcher is required whenever welding or cutting is done where more than a minor fire might develop or whenever any of the listed conditions in 1910.252(a)(2)(iii)(A)(1)–(4) exist, such as appreciable combustibles within 35 feet, combustible openings exposing hidden combustibles, or combustibles on the other side of partitions that could ignite. See 1910.252(a)(2)(iii)(A).

• If combustibles are closer than 35 feet, easily ignited at a greater distance, or concealed in walls/floors, you need a fire watcher.
• Always evaluate the area before authorizing hot work.

A fire watcher must have extinguishing equipment ready, be trained to use it, know how to sound an alarm, watch exposed areas for fires, try to extinguish only if within equipment capacity, and maintain the watch for at least a half hour after completion of the work. See 1910.252(a)(2)(iii)(B).

• A fire watcher must inspect concealed and exposed areas where smoldering fires might develop.
• If smoldering materials are found, the watcher should extinguish them if safe or sound the alarm and call for additional help.

The individual designated to authorize cutting and welding must inspect the area before work and set precautions, preferably issuing a written permit that states the required safeguards. See 1910.252(a)(2)(iv).

• Management should designate this responsible person and ensure they have authority to stop unsafe work.
• The permit should document hazards identified and controls required (guards, fire watch, extinguisher location, etc.).

If combustible materials like paper clippings, wood shavings, or textile fibers are on the floor, the floor must be swept clean for a radius of 35 feet around the work. See 1910.252(a)(2)(v).

• If floors are combustible, they must be kept wet, covered with damp sand, or shielded with fire-resistant covers.
• When floors are wet down, protect arc welding operators from electrical shock as required in the standard.

Cutting or welding is prohibited in areas not authorized by management, in sprinklered buildings where the sprinkler protection is impaired, in the presence of explosive atmospheres (including uncleaned tanks that held flammables), and near large quantities of exposed, readily ignitable materials. See 1910.252(a)(2)(vi)(A)–(D).

• Do not hot work in areas with combustible dust accumulations or flammable gas/vapor atmospheres.
• Clean and ventilate tanks and equipment thoroughly before any hot work; purge with inert gas is recommended per 1910.252(a)(3)(ii).

Combustibles should be relocated at least 35 feet from the work site whenever practicable; if they cannot be moved, they must be protected by flameproof covers or metal/asbestos shields. See 1910.252(a)(2)(vii) and 1910.252(a)(2)(xiv)(C)(2).

• Shields must prevent sparks and hot slag from reaching combustibles.
• Supervisors must also schedule operations so other plant activities won't expose combustibles during welding per 1910.252(a)(2)(xiv)(C)(3).

Ducts and conveyor systems that could carry sparks to distant combustibles must be suitably protected or shut down during welding or cutting. See 1910.252(a)(2)(viii).

• Protection can include installation of spark traps, shields, or temporary shutdown of the system until hot work is done.
• Evaluate concealed pathways (ducts, chutes) that could spread sparks to storage or other areas.

When welding or cutting near combustible walls, ceilings, or roofs, provide fire-resistant shields or guards to prevent ignition; when welding on metal walls or partitions, take precautions to prevent ignition of combustibles on the other side (preferably by relocating combustibles), or provide a fire watch on the opposite side. See 1910.252(a)(2)(ix) and 1910.252(a)(2)(x).

• Heat conduction or radiation through metal can ignite hidden combustibles—inspect both sides before starting.
• If combustibles cannot be moved, maintain a fire watch on the opposite side throughout and for at least 30 minutes after completion per 1910.252(a)(2)(iii)(B).

Welding shall not be done on metal partitions, walls, ceilings, or roofs that have combustible coverings, nor on sandwich-type panel constructions with combustible cores; do not weld on pipes or metal in contact with combustible materials if the work is close enough to cause ignition by conduction. See 1910.252(a)(2)(xi), 1910.252(a)(2)(xii), and 1910.252(a)(2)(xiii).

• If in doubt, relocate the work or the combustibles, or use approved shielding and fire watches.
• Management must establish procedures and designate an authorizer for such hot work per 1910.252(a)(2)(xiii)(A)–(B).

The supervisor must ensure safe handling and use of cutting/welding equipment, identify combustibles and hazards in the work location, secure authorization, confirm that welders obtain approval of safe conditions, ensure fire protection equipment is properly located, and provide fire watches when required. See 1910.252(a)(2)(xiv)(A)–(G).

• Supervisors should verify permits, shielding, housekeeping, and that personnel are trained for both normal work and emergency response.
• Documentation of inspections and permits is a best practice even if not strictly required by the text.

Hot work is only permitted in areas that are or have been made fire safe; if the work cannot be moved (as in construction), make the area safe by removing combustibles or protecting them from ignition sources before allowing cutting or welding. See 1910.252(a)(2)(xv).

• This includes using shields, wetting combustible floors, or applying damp sand as required in 1910.252(a)(2)(v).
• If safety measures cannot make the area fire safe, hot work must be postponed.

You must clean used drums, barrels, tanks, or other containers thoroughly to ensure no flammable materials, greases, tars, acids, or other residues remain; disconnect or blank any pipelines or connections, and vent hollow spaces before welding. See 1910.252(a)(3)(i)–(ii).

• Purging with an inert gas is recommended to remove flammable vapors.
• Never assume a container is safe; verify by testing and purge/vent as necessary before hot work.

When suspending arc welding for a substantial time (lunch, overnight), remove electrodes from holders, store holders to prevent accidental contact, and disconnect the machine from the power source; for gas torches, close torch valves and shut off gas supply outside confined areas and, where practicable, remove torch and hose. See 1910.252(a)(4)(i) and 1910.252(a)(4)(ii) and 1910.252(b).

• Closing valves outside a confined space reduces the chance of gas leaks in the confined area.
• These steps help prevent accidental ignition or release while equipment is unattended.

Welder and helper working on platforms, scaffolds, or runways must be protected against falling by railings, safety belts, lifelines, or other effective safeguards; welding cable and equipment must be placed so they do not obstruct passageways, ladders, and stairways. See 1910.252(b)(1)(i)–(ii).

• Use fall protection systems appropriate to the height and task.
• Route cables to avoid trip or fall hazards and to keep emergency egress clear.

Operators must use helmets or hand shields for arc welding or arc cutting (helpers need proper eye protection); goggles or suitable eye protection must be used for gas welding or oxygen cutting. Helmets, shields, and goggles must be insulating, not readily flammable, and provide protection for face, neck, and ears with filter and cover plates as required. See 1910.252(b)(2)(i)–(ii).

• Select filter lens shade and cover plates appropriate to the welding process and arc intensity.
• Ensure goggles are ventilated where practicable to reduce fogging per 1910.252(b)(2)(ii)(E).

Operators and attendants of resistance welding or resistance brazing equipment must use transparent face shields or goggles as required for the job; suitable goggles must be provided where needed for brazing operations not covered elsewhere. See 1910.252(b)(2)(i)(C)–(D).

• Choose eye/face protection based on the specific hazards of the operation (heat, sparks, slag, radiant energy).
• Ensure protection materials resist heat and are inspected for damage before use.

Helmets and hand shields must be made of material that insulates against heat and electricity, are not readily flammable, protect face/neck/ears from radiant energy, have removable filter and cover plates, and be constructed of material that will not readily corrode or discolor the skin. See 1910.252(b)(2)(ii)(A)–(D).

• Maintain and replace filter plates and cover plates as needed to ensure protection and visibility.
• Ensure helmets and shields meet the practical requirements for the welding process being performed.

A fire watcher must be trained in the use of extinguishing equipment and be familiar with alarm facilities; the person authorizing hot work should be designated by management and capable of inspecting the area and specifying precautions—ideally issuing a written permit. See 1910.252(a)(2)(iii)(B) and 1910.252(a)(2)(iv).

• Training should cover extinguisher selection, basic firefighting safe techniques, when to evacuate, and how to sound alarms.
• The authorizer should be knowledgeable about facility hazards, sprinkler status, and permit controls.

Use the shade numbers recommended in 1910.252(b)(2)(ii)(H) as a starting point and adjust for the worker's comfort and the job conditions. For example, the standard recommends Shade 10 for small shielded metal-arc welding electrodes and Shades 12–14 for heavier welding and arc operations, while soldering is Shade 2 and torch brazing is Shade 3 or 4.

• Use the table in 1910.252(b)(2)(ii)(H) to pick an initial shade by operation.
• If the torch produces a strong yellow light (e.g., some gas welding or cutting), consider a lens that absorbs the yellow/sodium line as the note in that paragraph suggests.
• Remember that individual vision needs may require a different shade than the table; the standard allows variation to suit the individual.

Cited: 1910.252(b)(2)(ii)(H).

Lenses must be tempered, free of optical flaws, and carry a permanent marking to identify source and shade. Specifically, the standard requires glass lenses to be tempered and substantially free from striae, air bubbles, waves and other flaws, with smooth, parallel surfaces unless optically ground; and lenses must bear a permanent distinctive marking so the source and shade can be identified.

• Inspect lenses before use for chips, distortion, or markings that are illegible.
• Replace lenses that are cracked, scratched, or whose marking is missing.

Cited: 1910.252(b)(2)(ii)(F) and 1910.252(b)(2)(ii)(G).

Yes — filter lenses must pass the transmission-of-radiant-energy tests in one of the consensus standards listed in 1910.133(b)(1). The rule requires that welding filter lenses meet the prescribed test for transmission of radiant energy, and those tests are found in the consensus standards incorporated by reference in 1910.133(b)(1).

• When buying filter lenses, confirm they comply with an ANSI/ISO or other consensus standard referenced in 1910.133(b)(1).

Cited: 1910.252(b)(2)(ii)(I) and 1910.133(b)(1).

When work permits, welders should be in individual booths or behind noncombustible screens to control glare and ultraviolet exposure; booths and screens must be noncombustible or flameproof, have low-reflectivity finishes, and allow air circulation at floor level.

• Booths should be painted with low-reflectivity finishes (e.g., zinc oxide, lamp black) to absorb UV radiation.
• Screens must be noncombustible or flameproof and protect nearby workers from rays; adjacent workers may instead be required to wear appropriate goggles if screens are not used.
• Arrange booths/screens so they do not block required ventilation (they should permit air circulation at floor level).

Cited: 1910.252(b)(3).

Gas cylinders and welding machines must be left outside the confined space whenever welding or cutting is performed inside. Additionally, portable equipment on wheels must be blocked to prevent accidental movement before operations begin.

• Keep all cylinders, regulators, and welding machines outside the confined space and route hoses through the entry.
• Secure heavy portable equipment mounted on wheels by blocking to prevent rolling.

Cited: 1910.252(b)(4)(iii).

Provide a means to quickly remove the welder, including lifelines/safety belts attached so the worker cannot be jammed, and station an attendant outside with a preplanned rescue procedure.

• Use lifelines and safety belts configured so the worker's body cannot be jammed in small exit openings.
• The attendant must continuously observe the worker and be ready to carry out the rescue plan.
• Ensure the rescue plan is preplanned and the attendant is trained to implement it.

Cited: 1910.252(b)(4)(iv).

When arc welding is suspended for a substantial period (lunch, overnight), remove all electrodes from holders, place holders so accidental contact cannot occur, and disconnect the machine from its power source.

• Store electrode holders so someone cannot touch a live electrode by accident.
• Disconnect the welding machine from its power source if it will not be used for a substantial period.

Cited: 1910.252(b)(4)(v).

Shut off torch valves and positively shut off the fuel-gas and oxygen supply at a point outside the confined area when the torch will not be used for a substantial period; remove torch and hose from the confined space where practicable.

• Close torch valves and shut supplies at a point outside the confined space to prevent gas escaping via leaking valves.
• Where practicable, remove the torch and hose from the confined space.

Cited: 1910.252(b)(4)(vii).

Employers must include welding-related hazardous materials (fluxes, coatings, filler metals, and substances released during welding) in their Hazard Communication program, provide labels and safety data sheets, and train employees per the Hazard Communication Standard.

• Ensure each employee has access to container labels and Safety Data Sheets (SDSs) for materials used in welding and cutting.
• Train employees about hazards and safe handling as required by 1910.1200.

Cited: 1910.252(c)(1)(iv) and 1910.1200.

Filler metals and fusible granular materials must carry, at minimum, a notice warning against use without adequate ventilation; filler metals with cadmium and fluxes with fluorine compounds must have labels identifying those specific hazards. Prior to June 1, 2015, employers could use specified alternative wording listed in 1910.252(c)(1)(vi).

• Containers must carry the minimum notice: "Do not use in areas without adequate ventilation." as described in 1910.252(c)(1)(v)(B).
• If filler metals contain cadmium in significant amounts, labels must indicate cadmium hazards (cancer, lung/kidney effects, acute toxicity) per 1910.252(c)(1)(v)(C).
• Fluxes with fluorine compounds must have labels warning about eye and respiratory effects per 1910.252(c)(1)(v)(D).
• Employers may refer to the alternate wording allowed prior to June 1, 2015, in 1910.252(c)(1)(vi).

Cited: 1910.252(c)(1)(v) and 1910.252(c)(1)(vi).

Mechanical ventilation is required when welding or cutting is done in spaces less than 10,000 cubic feet per welder, in rooms with ceilings under 16 feet, or in confined spaces or where partitions obstruct cross ventilation; the minimum rate is 2,000 cubic feet per minute per welder unless local exhaust or approved airline respirators are used.

• If the operation is in a space under 10,000 cubic feet per welder or in a low-ceiling room (<16 ft), provide mechanical ventilation per 1910.252(c)(2)(i).
• The required minimum general ventilation rate is 2,000 cubic feet per minute per welder unless local exhaust or approved airline respirators are provided.

Cited: 1910.252(c)(2)(i) and 1910.252(c)(2)(ii).

Position movable hoods as close as practicable to the work; the hood must be able to maintain a capture velocity of 100 linear feet per minute at the welding zone and the standard provides minimum airflow rates by distance.

• The hood should be placed near the arc/torch; when the hood is at its most remote distance, the airflow must still maintain about 100 linear ft/min in the welding zone.
• The standard's table in 1910.252(c)(3)(i) shows minimum cubic feet per minute and duct diameters for hood-to-arc distances (e.g., 150 cfm at 4–6 inches with a 3" duct).

Cited: 1910.252(c)(3)(i).

A fixed enclosure that surrounds welding or cutting operations must provide airflow sufficient to maintain a velocity away from the welder of at least 100 linear feet per minute.

• The enclosure must have a top and at least two sides and be arranged so the airflow keeps fumes moving away from the welder at ≥100 linear ft/min per 1910.252(c)(3)(ii).

Cited: 1910.252(c)(3)(ii).

Employers must provide and ensure use of appropriate PPE for welding, cutting, or brazing hazards, including eye/face protection, gloves, and protective clothing selected based on the job's hazards.

• Use the employer's hazard assessment under 1910.132 to select PPE.
• Protective clothing should be appropriate to the size, nature and location of the work per 1910.252(b)(3).
• Eye and face protection must meet the requirements cited elsewhere (e.g., filter lenses that meet 1910.133(b)(1)).

Cited: 1910.252(b)(3) and 1910.132.

You must design local exhaust or general ventilation to keep fumes, gases, and dust below the Permissible Exposure Limits (PELs) listed in 1910.1000.

• Determine the contaminants produced by the metal and process, then compare air measurements to the PELs in 1910.1000.
• Provide local exhaust or general ventilation adequate to maintain exposures below the PELs as required by 1910.252(c)(1)(iii).
• If exposures might exceed PELs, implement additional controls such as improved ventilation, fume collectors, or respiratory protection per applicable standards.

Cited: 1910.252(c)(1)(iii) and 1910.1000.

Contamination depends on workspace dimensions, number of welders, and metals/processes used; employers must include welding materials and fumes in their HCS program, provide labels/SDSs, and train employees.

• Assess contamination considering room size/ceiling height, number of welders, and potential evolution of hazardous fumes/gases from the metals and consumables as listed in 1910.252(c)(1)(i).
• Include fluxes, coatings, filler metals, and emissions from welding in the Hazard Communication program, and ensure employees have access to labels and SDSs and training per 1910.252(c)(1)(iv) and 1910.1200.

Cited: 1910.252(c)(1)(i) and 1910.252(c)(1)(iv).

All welding and cutting in confined spaces must be adequately ventilated so toxic gases don’t build up and oxygen is not depleted; the replacement air must be clean and respirable. See the ventilation requirement in 1910.252(c)(4)(i).

• Make sure ventilation protects the welder, helpers, and anyone nearby.
• "Adequately ventilated" means the system must prevent accumulation of toxic materials or oxygen deficiency under the actual work conditions.

(Authority: 1910.252(c)(4)(i).)

When you cannot provide adequate ventilation in a confined space, you must use airline respirators or hose masks that are approved by NIOSH under 42 CFR part 84. See 1910.252(c)(4)(ii) and the NIOSH approval requirement at 42 CFR part 84.

• Airline respirators deliver clean air from a remote source and are required when ventilation can’t keep atmospheres safe.
• Confirm respirators are NIOSH-approved for the intended use per 42 CFR part 84 before putting them into service.

(Authority: 1910.252(c)(4)(ii); see also 42 CFR part 84.)

In areas immediately hazardous to life, employers must provide a full-facepiece, pressure‑demand self‑contained breathing apparatus (SCBA) or a full‑facepiece, pressure‑demand supplied‑air respirator with an auxiliary self‑contained air supply approved by NIOSH under 42 CFR part 84. See 1910.252(c)(4)(iii) and the NIOSH approval requirement at 42 CFR part 84.

• Treat oxygen‑deficient or otherwise IDLH atmospheres as immediately dangerous to life; OSHA’s Respiratory Protection standard defines IDLH conditions and the protection required.
• For related guidance on oxygen‑deficient and IDLH atmospheres see OSHA’s interpretation on oxygen‑deficient atmospheres in HVAC, which explains how 29 CFR 1910.134 treats those conditions as IDLH and requires appropriate SCBA: Oxygen‑deficient atmospheres in HVAC.

(Authority: 1910.252(c)(4)(iii); see also 42 CFR part 84 and OSHA interpretation at https://www.osha.gov/laws-regs/standardinterpretations/2024-07-16.)

An outside helper must be stationed to ensure the safety of workers inside a confined space whenever welders and helpers are provided hose masks, hose masks with blowers, or self‑contained breathing equipment. See 1910.252(c)(4)(v).

• The outside helper monitors the workers inside, maintains communications, and can summon emergency help or initiate rescue if conditions change.
• This requirement applies whether the respiratory equipment is NIOSH‑approved or approved by MSHA/NIOSH as noted in the standard text.

(Authority: 1910.252(c)(4)(v); see also 42 CFR part 84 for respirator approvals.)

Oxygen must never be used for ventilation because adding pure oxygen increases fire and explosion risk and can create oxygen‑enriched atmospheres that make materials ignite more easily. See the prohibition at 1910.252(c)(4)(v).

• Use only clean, respirable air for replacement ventilation; do not introduce oxygen to dilute contaminants.
• Oxygen enrichment can make routine sparks and hot metal produce fast, intense fires that ordinary controls won’t safely handle.

(Authority: 1910.252(c)(4)(v).)

When welding or cutting in confined spaces on materials containing fluorine compounds, you must follow the confined‑space ventilation and respiratory protections in paragraph (c)(4) — meaning adequate ventilation or appropriate respirators. See 1910.252(c)(5)(i) and the linked ventilation rules in 1910.252(c)(4).

• For non‑confined or production welding, local exhaust ventilation or airline respirators are often needed, especially for stainless steels; paragraph (c)(5)(ii) says testing can show when such protection is not necessary if fluoride levels are below OSHA limits.
• If air monitoring under worst‑case conditions shows fluoride levels are below the allowable concentrations in 1910.1000, employers may be able to rely on those results to avoid extra respiratory controls.

(Authority: 1910.252(c)(5)(i); see also 1910.252(c)(4) and exposure limits at 1910.1000.)

If welding or cutting zinc‑bearing base or filler metals (or metals coated with zinc) in confined spaces, you must follow the confined‑space ventilation rules in paragraph (c)(4); indoors you must also follow paragraph (c)(3) ventilation requirements. See 1910.252(c)(6).

• Confined‑space work: use adequate ventilation or the respirators specified under 1910.252(c)(4).
• Indoors (non‑confined): control fumes per 1910.252(c)(3), which requires local exhaust ventilation or equivalent controls to keep exposures below applicable limits.

(Authority: 1910.252(c)(6); see also 1910.252(c)(4) and 1910.252(c)(3).)

Welding on lead‑base metals in confined spaces must follow the confined‑space rules in paragraph (c)(4); indoors the work must be done using local exhaust ventilation or airline respirators, and workers nearby must also be protected. See 1910.252(c)(7)(i)–(iii).

• Confined spaces: use the ventilation or respirator approaches in 1910.252(c)(4).
• Indoors: provide local exhaust ventilation or airline respirators for welders performing the work.
• Immediate vicinity: employees who work near the operation must also be protected by local exhaust ventilation or airline respirators.

(Authority: 1910.252(c)(7)(i)–(iii); see also exposure limits at 1910.1000.)

For beryllium, welding or cutting indoors, outdoors, or in confined spaces requires local exhaust ventilation and airline respirators unless worst‑case atmospheric tests show exposures are within the limits in [1910.1000]; nearby workers must also be protected. For cadmium, confined spaces and indoor operations must use local exhaust ventilation or airline respirators unless atmospheric tests under adverse conditions show exposures are within the allowable concentrations in [1910.1000]; outdoor cadmium work must use NIOSH‑approved respirators. See 1910.252(c)(8) and 1910.252(c)(9)(i)–(ii).

• Always confirm exposures with air sampling under the most adverse conditions before reducing controls.
• If outdoor operations generate cadmium fumes, use appropriate NIOSH‑approved respirators per 42 CFR part 84.

(Authority: 1910.252(c)(8); 1910.252(c)(9)(i)–(ii); see also 1910.1000 and 42 CFR part 84.)

You must follow manufacturers’ instructions for cleaning materials because of toxicity or flammability, and degreasing operations that use chlorinated hydrocarbons must be located so their vapors cannot reach welding atmospheres; avoid trichloroethylene and perchloroethylene in atmospheres penetrated by UV from gas‑shielded welding. See 1910.252(c)(11)(i)–(ii).

• Keep degreasing vapors away from welding areas to prevent toxic exposure or hazardous reactions.
• Specifically avoid trichloroethylene and perchloroethylene where gas‑shielded welding UV could convert them to harmful products.

(Authority: 1910.252(c)(11)(i)–(ii).)

Oxygen cutting (using chemical flux or iron powder) or gas‑shielded arc cutting of stainless steel must be done with mechanical ventilation adequate to remove the fumes generated. See 1910.252(c)(12).

• Mechanical local exhaust ventilation is commonly used to capture fumes at the source and keep worker exposures below limits in 1910.1000.
• If air monitoring shows exposures are below applicable limits under worst‑case conditions, employers may document that to justify reduced controls, but initial controls should assume fumes will be produced.

(Authority: 1910.252(c)(12); see also 1910.1000.)