By Clare Goldsberry, Associate Editor

The metals, fillers and electrodes used in welding produce fumes that to varying degrees can create hazardous situations for welder when they are not properly addressed in the work place. Safety considerations have long been key in avoiding preventing adverse affects from welding in all applications and materials.

Correct ventilation and air filtration are called for in welding, and there are a variety of products available to enhance and to ensure worker safety. Personal protective equipment (PPE) often is called for when working with metals and materials that pose the greatest hazards to worker health. And, some materials require extra precautions to ensure that workers are not exposed to potentially hazardous conditions.

Welding smoke is a mixture of very fine particles (fumes) and gases that could include substances such as chromium, nickel, arsenic, asbestos, manganese, silica, beryllium, cadmium, nitrogen oxides, phosgene, acrolein, carbon monoxide, cobalt, copper, ozone, and selenium. These substances are derived from a combination of the base metal, filler metals and welding rods, and from fluxes and rod coverings.

Welding standards available from the American Welding Society (www.aws.org) specify that minimum ventilation for welding should include systems that displace 2000 cfm (cubic feet per minute) of air.

However, the Occupational Safety and Health Administration (OSHA) (www.osha.gov) has different guidelines that concern specific metals and metals that have coatings that contain materials that could become hazardous under the conditions of welding or metal cutting with a torch.

For example: stainless steel alloys are produced with varying amounts of chromium, and hexavalent chromium could be formed in welding or cutting stainless steels. OSHA updated standards regarding exposure to hexavalent chromium in the workplace in 2006, and those standards were put into effect in stages, but became universally applicable to all industries and all shops, including those involved in the welding and hot cutting of stainless steel, on May 30.

Another example is welding or cutting metals with coatings such as galvanized metal that also could produce hazardous fumes during welding or cutting operations. OSHA recommendations call for an operator to use a supplied-air type respirator specifically designed to filter the specific metal fume when working with those types of coated materials and, of special consideration is welding beryllium copper. OSHA recommendations for berylliumcontaining base or filler metals, because of its high toxicity, that work involving beryllium be done with both local exhaust ventilation and air line respirators.

"Employees performing such operations in open air shall be protected by filter-type respirators in accordance with the requirements of Subpart E (of this regulation), except that employees performing such operations on beryllium-containing base or filler metals shall be protected by air-line respirators.

Brush Wellman Inc. (www.brushwellman.com), the leading supplier of beryllium metal products, acknowledges that welding provides the highest strength bond when joining copper beryllium to itself or to other metals, but states that care must be taken to prevent worker exposure and inhalation of fumes generated during the process.

The company's Technical Service Department provides an advisory on welding copper beryllium that notes that all welding needs to be done in an area with filtered ventilation of the exhaust to ensure worker safety and health. Brush Wellman also recommends that everyone who is consider welding copper beryllium products get detailed information from its Technical Service Deparmtment before starting the work, and be familiar with the material safety data sheets (MSDS) and other information for the specific copper beryllium welding application.

Another precaution comes for welding applications in parts that are filled with polyurethane foam, which is often used as an insulator in a variety of applications including building and construction and automotive materials. Welding parts filled with polyurethane foam can produce toxic gases, notes a safety data sheet from Arcraft Plasma.

Welding should not be attempted on parts filled with polyurethane foam, due to the generation of toxic gases caused by the thermal breakdown of the polyurethane foam.

Thermal decomposition of polyurethane foam associated with restricted amounts of oxygen as in the case of many welding operations results in different gases being produced than those produced in a clean, hot fire with adequate oxygen available. There are increased amounts of carbon monoxide, various aldehydes, isocyanates and cyanides, and small amounts of phosgene, all of which have varying degrees of toxicity. However, if repair by welding is absolutely necessary, the foam must be removed from the heat affected area, including the residue, prior to welding so that the torch is not touching any PU foam.

An excellent piece of advice to remember when welding any type of material is to know the toxicity of the materials involved in each welding job and verify that there is adequate ventilation to prevent exposure to metal fumes – or fumes from associated materials in the part such as PU foam – to both the welder or nearby workers.