Steels are coated to provide a protective covering or a decorative finish. Protective coatings are designed to prevent rusting or to shield the steel from chemical attack. Coatings found on steels can emit fumes, smoke, or dust, during joining and cutting. Coated steel's dusts, fumes or gases can harm welders and their exposure limits should not be exceeded.
Employers must be aware of what chemicals are released into the air that may injure welders. It is important that welders are trained in how to do each process the correct way and should only weld or cut after proper safety precautions have been taken.
A health hazard is created when large volumes of dust, fumes or gases are transmitted while coated steel is being welded or cut. Protective coatings on steels can contain chromium, lead, tin, zinc and other alloy materials. It is best practice for welders to understand the coating types for the materials they work with. If not, they should get this information from their supervisor or employer.
Paints are made up of compounds that may release hazardous materials into the air when heated. Paints are usually used on a phosphated and passivated (often with chromium) metal surfaces.
The heat from the arc can cause paints to give off unsafe amounts of gases like carbon monoxide and carbon dioxide. These also increase the risk of suffocation in confined work areas or those with poor air movement.
Steels coated with plastic materials should not be cut or welded unless proper precautions are taken. It is best to remove coating to a distance away from the weld or cut where the temperature won’t go above the point where the material starts to break down.
For additional information, see AWS Fact Sheet 1, Fumes and Gases.