Although some rigging shops may have more extensive welding operations compared to others, many shops probably have an occasional need to perform a certain type of welding from time to time. Welding may be product related such as welding links for a chain sling or welding for a custom engineered lifting device.A shop may have reason to weld related to maintenance or repair of a specific piece of equipment in their facility. Regardless of what type of welding, it is critical to understand that the welding process exposes the welders and coworkers to harmful metal fume and gas by-products.
Welding falls into one of two classification groups. One group is fusion welding, which is heat alone. The three types of fusion welding are electric arc, gas, and thermit. Electric arc welding is the most common. It uses an electric arc to melt the base and filler metals. The other welding classification is pressure welding, which involves heat and pressure.
The arc welding types in the order of decreasing fume production:
• Flux core arc welding (FCAW) – filler metal electrode; flux shield
• Shielded Metal Arc (SMAW) – electrode provides both flux and filler material
• Gas Metal Arc (GMAW or MIG) – widely used; consumable electrode for filler metal, external gas shield
MIG is the most versatile and the easiest type to learn. TIG is the most aesthetically pleasing. Gas or oxy-fuel welding uses a flame from burning a gas – often acetylene. The gas melts metal at a joint to be welded. This type of welding is common when welding iron, steel, cast iron, and copper.
Rather than utilizing gas fuel or electric current, thermit welding uses a chemical reaction to generate intense heat.
Pressure welding combines heat and impact-type pressure to join the metal.
Oxy-fuel, plasma cutting and brazing involve the melting of metal which then produces airborne metal fume. Brazing is a metal-joining process in which two or more metal items are joined by melting and flowing a filler metal into the joint, the filler metal having a lower melting point than the adjoining metal. Brazing does not involve the melting of the base metal.
Welding fumes are a complex mixture of metallic oxides, silicates and fluorides. Fumes are formed when a metal is heated above its boiling point and its vapors condense into very fine particles (solid particulates). Welding fumes generally contain particles from the electrode and the material being welded.
Factors that affect exposure to the welding fume are (a) type of welding process, (b) base metal and filler metals used, (c) welding rod composition, (d) location – outside or enclosed space, (e) welder work practices, (f) air movement, and (g) use of ventilation controls.
OSHA has indicated that intense exposure to welding fumes can result in irritation to the eyes, nose and throat. It can also lead to dizziness and nausea. If workers experience any of these symptoms, they should immediately leave the area, seek fresh air, and attain medical attention. Extended exposure to welding fumes can cause cancer of the lung, larynx and urinary tract. It can also affect the kidneys and nervous system.
Welders can take precautions in order to manage the risks associated with fume exposure.
Per OSHA, precautions include:
• Ensure that workers understand the hazards associated with welding
• Clean welding surfaces that could contain toxic exposure such as solvent residue and paint.
• Position workers away from welding fumes and gases. If open or outdoor areas, stay upwind. Welding in open areas or outdoors may not always assure proper ventilation.
• For indoor welding, use local exhaust ventilation systems to remove fumes and gases from the welder’s work area. Be sure to keep exhaust ports away from coworkers.
• Avoid welding in a confined space that does not have enough adequate ventilation.
• Utilize respiratory protection if welding processes and ventilation do not reduce exposure to safe levels.
Per OSHA, industrial hygiene is the science of anticipating, recognizing, evaluating, and controlling workplace conditions that may cause workers’ injury or illness. Industrial hygienists use environmental monitoring and analytical methods to detect the extent of worker exposure and employ engineering, work practice controls, and other methods to control potential health hazards. To gain a better understanding of possible exposures in your specific facility, you may want to consider an industrial hygiene sampling. Making use of such a sampling provides and opportunity to collect data and establish a baseline to then incorporate (with assistance or recommendations from the Industrial Hygienists) control methods to help bring down the exposure levels if needed.
For further information related to welding in the workplace, here are some OSHA standards you may want to review:
Welding, Cutting and Brazing – 29 CFR 1910 Subpart Q
Welding & Cutting – 29 CFR 1926 Subpart J
Welding, Cutting & Heating – 29 CFR 1915 Subpart D
Permit-required Confined Spaces – 29 CFR 1910.146
Confined & Enclosed Spaces & Other Dangerous Atmospheres in Shipyard Employment – 29 CFR 1915 Subpart B
Hazard Communication – 29 CFR 1910.1200
Respiratory Protection – 29 CFR 1910.134
Air Contaminants – 29 CFR 1910.1000 (general industry), 29 CFR 1915.1000 (shipyards), 29 CFR 1926.55 (construction)