These welding consumables significantly reduce fume emission rate (FER), by up to 40%, and CrVI emissions by up to 60%; which can help create a better working environment for welders.
Local and regional governments have imposed occupational exposure limits (OELs) or total airborne particle limits that vary from 1.0 mg/m3 in Netherlands to 5.0 mg/m3 in the UK, Australia and South Africa. But welding fumes can contain chemical elements such as CrVI with their own OEL values.
French decree No. 2012-746 limits values for occupational exposure and more restrictive values were applied in France from 1st of July 2014. The eight-hour OEL limit of CrVI, for example, changed from 50 µg/m3 to the new limit of 1.0 µg/m3 OEL with a 15-minute short-term limit of less than 5.0 µg/m3.
As hexavalent chromium may be present in the welding fume generated by stainless steel welding consumables, users and employers of stainless steel welding consumables should assess the potential exposure to CrVI in their workplace, and the appropriate welding fume control solutions needed to keep exposures to levels below applicable OELs. When assessing the welding fume control solutions to use, in addition to considering personal protection equipment (PPE) and fume extraction systems, users and employers should also consider changing the welding consumable itself, which could reduce hexavalent chromium generation at the outset and lead to a positive impact on working conditions and environment.
The formation mechanism and CrVI reduction techniques are well known [ref.1], but the weldability of consumable products designed to reduce CrVI from welding consumables has previously proven inferior to those currently used in the field. Also, in the case of stick electrodes, poor extrusion behaviour and poor adherence and coating resistance during manufacture has prevented these consumables from reaching general market acceptance.
To meet this CrVI OELs and prevent risks for users and their environment, many methods for reducing airborne levels of CrVI are available, but when welding stainless steel, it may only be possible to stay below these levels by combining several available fume control solutions.
Welding consumables such as stick electrodes and cored wires with low CrVI source emission levels will, therefore, be a very valuable new tool to users and employers working to meet the new safety limits.
CrVI fume generation principles
Fumes emitted during welding result from complex processes of evaporation, condensation and oxidation mechanisms and their combination. These phenomena, as shown by Figure 1, generate fume at droplet level: inside the arc column; during spatter formation; or in the molten weld pool.
During stainless steel welding ...