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Ventilation Requirements

Ventilation for General Welding and Cutting

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.

Provide mechanical ventilation welding or cutting if done on metals:

  • In a space of less than 10,000 cubic feet (284 m (3)) per welder.
  • In a room having a ceiling height of less than 16 feet (5 m).
  • In confined spaces or where the welding space contains partitions, balconies, or other structural barriers to the extent that they significantly obstruct cross ventilation.

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:

  • Hoods: The welder should place freely movable hoods as near as possible to the welded work. These hoods should have a rate of airflow of 100 linear feet (30 m) per minute in the zone of welding when the hood farthest from the point of welding.
  • Fixed enclosure: A fixed enclosure with a top, and not less than two sides, which surround the welding or cutting operations and with a rate of airflow sufficient to maintain a velocity away from the welder of not less than 100 linear feet (30 m) per minute.
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.

Ventilation in Confined Spaces

ventilation

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:

  • a full-facepiece, pressure-demand, self-contained breathing apparatus, or
  • a combination full facepiece, pressure demand supplied-air respirator with an auxiliary, self-contained air supply approved by NIOSH.

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.

Confined Space Welding Explosion
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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:

  • Close the torch valves. Also, completely shut off the fuel-gas and oxygen supply to the torch at some point outside the confined area.
  • Remove the torch and hose from the confined space when it is practicable.

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.

Hazard Communication

The following three factors in arc and gas welding govern the amount of contamination to which welders may be exposed:

  • dimensions of space in which welding is to be done (with special regard to the height of the ceiling)
  • number of welders
  • possible evolution of hazardous fumes, gases, or dust according to the metals involved

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:

  • The suppliers must determine and must properly label any hazards associated with the use of their materials in welding, cutting, and brazing.
  • All filler metals and fusible granular materials must carry the following notice, as a minimum, on tags, boxes, or other containers:

“Do not use in areas without adequate ventilation. See ANSI Z49.1-1967 Safety in Welding, Cutting, and Allied Processes published by the American Welding Society.”

  • Where brazing (welding) filler metals contain cadmium in significant amounts, the labels must indicate the hazards associated with cadmium including cancer, lung and kidney effects, and acute toxicity effects.
  • Where brazing and gas welding fluxes contain fluorine compounds, the labels must indicate the hazards associated with fluorine compounds including eye and respiratory tract effects.

Oxygen for Ventilation

  • Never use oxygen for ventilation.

Gases and Fumes

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
acrolein arsenic asbestos beryllium
cadmium carbon monoxide chromium cobalt
copper fluorine compounds lead manganese
nickel nitrogen oxides ozone phosgene
selenium silica zinc

Beryllium

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.

Cadmium

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.

Fluorine Compounds

In confined spaces, welding or cutting involving fluxes, coverings, or other materials which contain fluorine compounds must be done in accordance with 1910.252(c)(4). A fluorine compound is one that contains fluorine, as an element in chemical combination, not as a free gas.

Indoors: 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).

Lead

Confined spaces: In confined spaces, welding involving lead-base metals (erroneously called lead-burning) must be done in accordance with 1910.252(c)(3).

Indoors: Indoors, welding involving lead-base metals must 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, should be done using local exhaust ventilation or airline respirators.

Operations performed outdoors, should use respirators approved for this purpose by NIOSH. In all cases, local exhaust ventilation or airline respirators should protect workers in the immediate vicinity of the cutting operation.

Mercury

In confined spaces or indoors, welding or cutting operations involving metals coated with mercury-bearing materials, including paint, should be done using local exhaust ventilation or airline respirators, unless atmospheric tests under the most adverse conditions show employee exposure is within the acceptable concentrations specified by 29 CFR 1910.1000. Such operations, when done outdoors, should be done using respirators approved for this purpose by NIOSH.

Zinc

Confined spaces: In confined spaces welding or cutting involving zinc-bearing base or filler metals or metals coated with zinc-bearing materials must be done in accordance with 1910.252(c)(4).

Cleaning Compounds

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.

Cutting of Stainless Steels

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

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.

Instructions

Before beginning this quiz, we highly recommend you review the module material. This quiz is designed to allow you to self-check your comprehension of the module content, but only focuses on key concepts and ideas.

Read each question carefully. Select the best answer, even if more than one answer seems possible. When done, click on the "Get Quiz Answers" button. If you do not answer all the questions, you will receive an error message.

Good luck!

1. When must mechanical ventilation be provided when welding or cutting is done on metals in a confined space?

2. When welding or cutting is being performed in any confined spaces the gas cylinders and welding machines must _____.

3. When welding in confined spaces, each of the following factors in arc and gas welding governs the amount of contamination to which welders may be exposed, EXCEPT:

4. Oxygen must _____ be used for ventilation.

5. When welding exposes workers to lead, zinc, mercury, and cadmium, which of the following personal protective equipment should be used?


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