Health Protection, Safety and Welding Ventilation

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Health Protection, Safety and Welding Ventilation

Summary:

All welding and thermal cutting operations carried on in confined
spaces must be adequately ventilated to prevent the accumulation of
toxic materials, combustible gases, or possible oxygen deficiency.

Monitoring instruments should be used to detect harmful
atmospheres. Where it is impossible to provide adequate ventilation,
air-supplied respirators or hose masks approved for this purpose must be
used.

In these situations, lookouts must be used on the outside of the confined space to ensure the safety of those working within.

Requirements in this section describe standards established for arc and gas welding and cutting.

A certified industrial hygienist should be consulted to understand the correct approach for your specific situation.

Extractor of Welding Fumes

Exhaust Ventilation using welding Fume Extractor that is mounted on the wall.

Overview

These requirements will govern the amount of contamination to which welders may be exposed:

  1. Dimensions of the area in which the welding process takes place (with special regard to height of ceiling).
  2. Number of welders in the room.
  3. Possible development of hazardous fumes, gases, or dust according to the metals involved.
  4. Location of welder's breathing zone with respect to rising plume of fumes.

In specific cases, there are other factors involved
in which respirator protective devices (ventilation) should be provided
to meet the equivalent requirements of this section. They include:

  1. Atmospheric conditions.
  2. Generated heat.
  3. Presence of volatile solvents.

In all cases, the required health protection,
ventilation standards, and standard operating procedures for new as well
as old welding operations should be coordinated and cleaned through the
safety inspector and the industrial hygienist having responsibility for
the safety and health aspects of the work area.

Screen Areas

When welding must be performed in a space entirely screened on all
sides, the screens shall be arranged so that no serious restriction of
welding ventilation fumes exists.

It is desirable to have the screens mounted so that
they are about 2.0 ft (0.6 m) above the floor, unless the work is
performed at such a low level that the screen must be extended closer to
the floor to protect workers from the glare of welding.

Concentration of Toxic Substances

Local exhaust or general ventilating systems shall be provided and
arranged to keep the amount of toxic frees, gas, or dusts below the
acceptable concentrations as set by the American National Standard
Institute
Standard 7.37; the latest Threshold Limit Values (TLV) of the
American Conference of Governmental Industrial Hygienists; or the
exposure limits as established by Public Law 91-596, Occupational Safety
and Health Act of 1970.

Compliance shall be determined by sampling of the
atmosphere. Samples collected shall reflect the exposure of the persons
involved. When a helmet is worn, the samples shall be collected under
the helmet.

Respiratory Protective Equipment

Individual respiratory protective equipment will be well retained. Only
respiratory protective equipment approved by the US Bureau of Mines,
National Institute of Occupational Safety and Health, or other
government-approved testing agency shall be utilized. Guidance for
selection, care, and maintenance of respiratory protective equipment is
given in Practices for Respiratory Protection, American National
Standard Institute Standard 788.2 and TB MED 223. Respiratory protective
equipment will not be transferred from one individual to another
without being disinfected.

Precautionary Labels

A number of potentially hazardous materials are used in flux coatings, coverings, and filler metals.

These materials, when used in welding and cutting
operations, will become hazardous to the welder as they are released
into the atmosphere.

These include, but are not limited to, the following
materials: fluorine compounds, zinc, lead, beryllium, cadmium, and
mercury.

The suppliers of
welding materials shall determine the hazard, if any, associated with
the use of their materials in welding, cutting, etc.

All filler metals and fusible granular materials
shall carry the following notice, as a minimum, on tags, boxes, or other
containers:

CAUTION

 

 

Welding may produce fumes and gases hazardous to health.

Avoid breathing these fumes and gases.

Use adequate ventilation. See American National
Standards Institute Standard Z49.1-1973, Safety in Welding and Cutting
published by the American Welding Society.

Brazing (welding) filler metals containing cadmium
in significant amounts shall carry the following notice on tags, boxes,
or other containers:

WARNING
CONTAINS CADMIUM - POISONOUS FUMES MAY BE FORMED ON HEATING

Do not breathe fumes.

Use only with adequate ventilation, such as fume collectors, exhaust ventilators, or air-supplied respirators.

See American National Standards Institute Standard
Z49.1-1973. If chest pain, cough, or fever develops after use, call
physician immediately.

Local Exhaust Ventilation

Welding Ventilation Booth

A welding ventilation booth provides a safe barrier for containing heat, sparks and fumes.

Mechanical local exhaust welding ventilation may be obtained by either of the following means:

  1. Hoods.Freely movable hoods or ducts are intended to be placed by the welder as near as practicable to the work being welded.

    These will provide a rate of airflow sufficient to
    maintain a velocity the direction of the hood of 100 in linear feet per
    minute in the zone of welding.

  2. Fixed enclosure.A fixed enclosure with a top and two or more sides
    which surrounds the welding or cutting operations will have a rate of
    airflow sufficient to maintain a velocity away from the welder of not
    less than 100 linear ft per minute.

    Downdraft ventilation tables require 150 cu ft per minute per square foot of surface area.

    This rate of exhausted air shall be uniform across the face of the grille.

    A low volume, high-density fume exhaust device attached
    to the welding gun collects the fumes as close as possible to the point
    of origin or at the arc.

    This method of fume exhaust has become quite popular
    for the semiautomatic processes, particularly the flux-cored arc welding
    process.

    Smoke exhaust systems incorporated in semiautomatic
    guns provide the most economical exhaust system since they exhaust much
    less air they eliminate the need for massive air makeup units to provide
    heated or cooled air to replace the air exhausted.

    Local ventilation should have a rate of air flow
    sufficient to maintain a velocity away from the welder of not less than
    100 ft (30 m) per minute.

    Air velocity is measurable using a velometer or air
    flow inter. These two systems can be extremely difficult to use when
    welding other than small weldments.

    The down draft welding work tables are popular in Europe but are used to a limited degree North America.

    In all cases when local ventilation is used, the exhaust air should be filtered.

Welding Ventilation Hood

A welding ventilation hood will remove fumes and smoke from welding stations and molding processes.

Ventilation in Confined Space

Welding Ventilation for a Confined Space

When working in a confined space a welding ventilation device such as the one pictured is required to remove any plume

Air Replacement

Ventilation is a perquisite to work in confined spaces.

All welding and cutting operations in confined spaces
shall be adequately ventilated to prevent the accumulation of toxic
materials -or possible oxygen deficiency.

This applies not only to the welder but also to helpers and other personnel in the immediate vicinity.

Airline Respirators

In circumstances where it is impossible to provide adequate
ventilation in a confined area, airline respirators or hose masks,
approved by the US Bureau of Mines, National Institute of Occupational
Safety and Health, or other government-approved testing agency, will be
used for this purpose.

The air should meet the standards established by Public Law 91-596, Occupational Safety and Health Act of 1970.

Self-contained Units

In areas immediately hazardous to life, hose masks with blowers or self-contained breathing equipment shall be used.

The breathing equipment shall be approved by the US
Bureau of Mines or National Institute of Occupational Safety and Health,
or other government-approved testing agency.

Outside Helper

Where welding operations are carried on in confined spaces and where
welders and helpers are provided with hose masks, hose masks with
blowers, or self-contained breathing equipment, a worker shall be
stationed on the outside of such confined spaces to ensure the safety of
those working within.

Oxygen for Ventilation

Oxygen must never be used for ventilation.

Local Welding Exhaust Ventilation

Welding Ventilation for fume extraction. Proper ventilation helps reduce exposure to toxic fumes given off by metals such as manganese, iron and lead.

Ventilation for Flourine Compounds

In confined spaces, welding or cutting involving fluxes, coverings,
or other materials which fluorine compounds shall be done in accordance
with paragraph 2-4 h, ventilation in confined spaces.

A fluorine compound is one that contains fluorine as an element in chemical combination, not as a free gas.

Maximum allowable concentration.

 

The need for local exhaust ventilation or airline
respirators for welding or cutting in other than confined spaces will
depend upon the individual circumstances.

However, experience has shown that such protection is
desirable for fixed-location production welding and for all production
welding on stainless steels.

When air samples taken at the welding location indicate
that the fluorides liberated are below the maximum allowable
concentration, such protection is not necessary.

Zinc

  1. Zinc Welding Ventilation in Confined spacesIn confined spaces, welding or cutting involving
    zinc-bearing filler metals or metals coated with zinc-bearing materials
    shall be done in accordance with regulations on ventilation in
    confined spaces
    .
  2. IndoorsIndoors, welding or cutting involving zinc-bearing
    metals or filler metals coated with zinc-bearing materials shall be done
    in accordance with local exhaust ventilation regulations.

Lead

  1. Confined spacesIn confined spaces, welding involving lead-base metals (erroneously called lead-burning) shall be done in accordance with guidelines on ventilation in confined spaces.
  2. IndoorsIndoors, welding involving lead-base metals shall be done in accordance with guidelines on local exhaust ventilation.
  3. Local ventilationIn confined spaces or indoors, welding or cutting involving metals containing lead or metals coated with lead-bearing materials, including paint, shall be done using local exhaust ventilation or airline respirators.

Outdoors, such operations shall be done using respirator protective equipment approved by the US Bureau of Mines, National Institute of Occupational Safety and Health, or other government-approved testing agency.

In all cases, workers in the immediate vicinity of the cutting or welding operation shall be protected as necessary by local exhaust ventilation or airline respirators.

Beryllium

Welding or cutting indoors, outdoors, or in confined spaces involving beryllium-bearing material or filler metals will be done using local exhaust ventilation and airline respirators.

This must be performed without exception unless atmospheric tests under the most adverse conditions have established that the workers´ exposure is within the acceptable concentrations of the latest Threshold Limit Values (TLV) of the American Conference of Governmental Industrial Hygienists, or the exposure limits established by Public Law 91-596, Occupational Safety and Health Act of 1970.

In all cases, workers in the immediate vicinity of the welding or cutting operations shall be protected as necessary by local exhaust ventilation or airline respirators.

Cadmium

  1. General.Welding or cutting indoors or in confined spaces involving cadmium-bearing or cadmium-coated base metals will be done using local exhaust ventilation or airline respirators.

    Outdoors, such operations shall be done using respiratory protective equipment such as fume respirators, approved by the US Bureau of Mines, National Institute of Occupational Safety and Health, or other government-approved testing agency, for such purposes.

  2. Confined space.Welding (brazing) involving cadmium-bearing filler metals shall be done using ventilation as prescribed in the paragraph above on local exhaust ventilation, and ventilation in confined spaces, if the work is to be done in a confined space.

NOTE
Cadmium-free rods
are available and can be used in most instances with satisfactory results.

Mercury

Welding or cutting indoors or in a confined space involving metals coated with mercury-bearing materials, including paint, shall be done using local exhaust welding ventilation or airline respirators. Outdoors, such operations will be done using respiratory protective equipment approved by the National Institute of Occupational Safety and Health, US Bureau of Mines, or other government-approved testing agency.

Fume Extractor

A source capture extroactor will remove particulates and fumes as they are emitted when welding.

Cleaning Compounds

  1. Manufacturer´s instructions.In the use of cleaning materials, because of their toxicity of flammability, appropriate precautions listed in the manufacturer´s instructions will be followed.
  2. Degreasing.Degreasing or other cleaning operations involving chlorinated hydrocarbons will be located so that no vapors from these operations will reach or be drawn into the area surrounding any welding operation. In addition, trichloroethylene and perchloroethylene should be kept out of atmospheres penetrated by the ultraviolet radiation of gas-shielded welding operations.

 

Cutting of Stainless Steels

Oxygen
cutting, using either a chemical flux or iron powder, or gas-shielded
arc cutting of stainless steel will be done using mechanical ventilation
adequate to remove the fumes generated.

First-Aid Equipment

First-aid
equipment will be available at all times. On every shift of welding
operations, there will be personnel present who are trained to render
first-aid.

All welding ventilation related injuries will be
reported as soon as possible for medical attention. First-aid will be
rendered until medical attention can be provided.

Brochures

Welding Fumes and Ventilation
Author: American Welding Society

References for Welding Ventilation

Canadian Metal Working

OSHA Ventilation Standards

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Page Author: Jeff Grill