Control of exposure to hexavalent chromium concentration in shielded metal arc welding fumes by nano-coating of electrodes

Abstract

Background: Cr(VI) is a suspected human carcinogen formed as a by-product of stainless steel welding. Nano-alumina and nano-titania coating of electrodes reduced the welding fume levels.

Objective: To investigate the effect of nano-coating of welding electrodes on Cr(VI) formation rate (Cr(VI) FR) from a shielded metal arc welding process.

Methods: The core welding wires were coated with nano-alumina and nano-titania using the sol-gel dip coating technique. Bead-on plate welds were deposited on SS 316 LN plates kept inside a fume test chamber. Cr(VI) analysis was done using an atomic absorption spectrometer (AAS).

Results: A reduction of 40% and 76%, respectively, in the Cr(VI) FR was observed from nano-alumina and nano-titania coated electrodes. Increase in the fume level decreased the Cr(VI) FR.

Discussion: Increase in fume levels blocked the UV radiation responsible for the formation of ozone thereby preventing the formation of Cr(VI).

Keywords:

• Coated electrodes
• Taguchi methodology
• Cr(VI) FR
• constituent analysis

Acknowledgements

The authors are grateful to the Director, National Institute of Technology (NIT), Tiruchirappalli for his continual encouragement and support to this work. The authors profusely thank Technical Education Quality Improvement Programme (TEQIP), NIT Trichy for its support to this work. The authors thank Sophisticated Analytical Instrument Facility (SAIF), Indian Institute of Technology (IIT), Madras for providing facilities to carry out ICP analysis. The authors also thank M/s. Seven Arc Welding Industries, Thuvakkudi, Trichy, M/s. Mantek Welding Industries, Bell Nagar, Trichy and M/s. SunMachX Engineering Industries, Thuvakkudi, Trichy for providing facilities for flux coating.