The most common compounds in arc welding fumes from mild steel are iron, manganese and silicon, although other compounds in the electrode or on the base metal may be in the welding fumes.
Fumes from the use of stainless steel and hardfacing products contain chromium and/or nickel.
Some forms of these metals are known or suspected to cause lung cancer in processes other than welding, and asthma has been reported. Therefore, it is recommended that precautions be taken to keep exposures as low as possible.
Manganese overexposure may affect the central nervous system, resulting in poor coordination, difficulty in speaking, and tremor of arms or legs. This condition is considered irreversible.
This depends on the electrode and other factors. Check the LH7018 (SDS sheet), including comments on siderosis and irritation of nose and throat.
Overexposure to zinc may cause fume fever with symptoms similar to the common flu.
Zinc in welding fumes usually comes from welding galvanized steel.
Each welding power source and container of consumable product has a warning label which contains specific safety instructions regarding the arc welding product you have chosen to use.
It contains:
a) Additional information including a summary of the Hazardous Materials used to manufacture
the product.
b) A summary of Fire and Explosion Hazard Data, Health Hazard Data and Reactivity Data.
c) Information on the precautions to observe for the Safe Handling and Use of the product.
a) Inside each container of a Lincoln Electric consumable.
b) It can also be found on the Lincoln Electric website.
c) On the American Welding Society website.
d) From your supervisor.
a) Keep fumes and gases from your breathing zone and general area.
b) Keep your head out of the fumes.
c) Use enough ventilation, or exhaust at the arc, or both, to keep
fumes and gases from your breathing zone and general area.
If special ventilation products are used indoors, use local exhaust. If special ventilation products are used outdoors, a respirator may be required.
Hardfacing and stainless products.
Most of the shielding gases (argon, helium, and carbon dioxide) are nontoxic, but they can displace oxygen in your breathing air, causing dizziness, unconsciousness, and possibly death. Carbon monoxide can also be present and may pose a hazard if levels are excessive.
Keep your head out of the fume plume!
The concentration of fumes and gases is greatest in the plume.
Keep fumes and gases from your breathing zone and general area using natural ventilation, mechanical ventilation, fixed or moveable exhaust hoods or local exhaust at the arc.
It may be necessary to wear a NIOSH approved respirator if adequate ventilation cannot be provided.
OSHA requires that engineering and workplace controls be installed first and, if the controls alone do not keep exposures below applicable limits, used with respirators.
As a practical rule of thumb for welders, for many mild steel electrodes, if the welder is comfortable and the air is visibly clear, the welder has adequate ventilation. However, a welder’s exposure can only be determined by having a qualified professional take a sample of your breathing air zone during a workday.
A welder‘s exposure can only be determined by having a qualified professional take a sample of your breathing air during the workday.
Measuring a welder‘s exposure to welding fumes is essential if you are welding with stainless, hardfacing or other special ventilation products (see the product label).
If the base metal cannot be cleaned before welding, the composition of the coating should be evaluated.
Stop welding and get some fresh air immediately. If you continue to feel the symptoms, see your doctor. Notify your supervisor and coworkers so the situation can be corrected and other workers are aware of and can avoid the hazard. Be sure you are following safe practices, as stated on the consumable labeling and SDS, and improve the ventilation in your area. Do not continue welding until the situation has been corrected.
Your work area has adequate ventilation when there is enough ventilation and/or exhaust to control worker exposure to hazardous materials in the welding fumes and gases so the applicable exposure limit for those materials is not exceeded.
The two most common U.S. exposure limits are established by OSHA in the form of Permissible Exposure Limits or PEL and by the ACGIH in the form of Threshold Limit Values or TLV.
Your employer must keep exposures below the PEL.
The PEL and TLV are listed on the first page of the SDS for compounds in each electrode or flux.
Natural ventilation is the movement of air through the workplace caused by natural forces.
Outside, this is usually the wind. Inside, this may be the flow of air through open windows and doors.
Mechanical ventilation is the movement of air through the workplace caused by an electrical device such as a portable fan or permanently mounted fan in the ceiling or wall.
Local exhaust is a mechanical device used to capture welding fumes at or near the arc and remove contaminants from the air.
The ventilation or exhaust needed for your application depends upon many factors, such as:
- Workspace volume
- Workspace configuration
- Number of welders
- Welding process and current
- Consumables used (mild steel, hardfacing, stainless, etc.)
- Allowable levels (TLV, PEL, etc.)
- Material welded (including paint or plating)
- Natural airflow
Local exhaust of welding fumes can be provided by any of the following: adjustable “elephant trunk” exhaust systems; fume extraction guns; or fixed enclosures or booths with exhaust hoods.
Local exhaust systems are more effective and economical to operate than a general ventilation system, particularly in the winter, because they require less replacement air to be brought into the room and heated.
Minimum required air velocity at the welding arc is 100 fpm.
Exposure should be checked when new ventilation equipment is installed, the process is modified or the welder feels uncomfortable. Periodically, exposure should be rechecked to be sure it is still working properly and is adequate.
Keep exposure as low as possible and below exposure limit values (PEL and TLV) for materials in the fumes using local exhaust. A respirator should be used unless exposure assessments confirm that ventilation is adequate to control worker exposure.
In confined spaces or in some circumstances, for example outdoors, a respirator may be required if exposure cannot be controlled to the PEL or TLV.
According to OSHA regulations, when welding and cutting (mild steels), natural ventilation is usually considered sufficient to meet requirements, provided that:
- The room or welding area contains at least 10,000 cubic feet (283 m3) (about 22’ x 22’ x 22’) for each welder.
- The ceiling height is not less than 16 feet.
- Cross ventilation is not blocked by partitions, equipment, or other structural barriers.
- Welding is not done in a confined space.
- Regardless of whether the ventilation meets these requirements, the welder‘s exposure must be controlled to below the PEL or TLV (if applicable) exposure limit to be adequate.