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Selecting processes to minimize hexavalent chromium from stainless steel welding.

Authors
Keane-M; Siert-A; Stone-S; Chen-B; Slaven-J; Cumpston-A; Antonini--J
Source
Welding J 2012 Sep; 91(9):241s-246s
NIOSHTIC No.
20041532
Abstract
Eight welding processes/shielding gas combinations were assessed for generation of hexavalent chromium (Cr6+) in stainless steel welding fumes. The processes examined were gas metal arc welding (GMAW) (axial spray, short circuit, and pulsed spray modes), flux cored arc welding (FCAW), and shielded metal arc welding (SMAW). The Cr6+ fractions were measured in the fumes; fume generation rates, Cr6+ generation rates, and Cr6+ generation rates per unit mass of welding wire were determined. A limited controlled comparison study was done in a welding shop including SMAW, FCAW, and three GMAW methods. The processes studied were compared for costs, including relative labor costs. Results indicate the Cr6+ in the fume varied widely, from a low of 2800 to a high of 34,000 ppm. Generation rates of Cr6+ ranged from 69 to 7800 ug/min, and Cr6+ generation rates per unit of wire ranged from 1 to 270 ug/g. The results of field study were similar to the findings in the laboratory. The Cr6+ (ppm) in the fume did not necessarily correlate with the Cr6+ generation rate. Physical properties were similar for the processes, with mass median aerodynamic diameters ranging from 250 to 336 nm, while the FCAW and SMAW fumes were larger (360 and 670 nm, respectively). Conclusion: The pulsed axial spray method was the best choice of the processes studied based on minimal fume generation, minimal Cr6+ generation, and cost per weld. This method is usable in any position, has a high metal deposition rate, and is relatively simple to learn and use.
Keywords
Welding-industry; Welding-equipment; Welding; Welders; Fumes; Arc-welding; Metal-fumes; Metal-compounds; Metallic-compounds; Metallic-fumes; Analytical-processes; Hazards; Gases; Gas-welders; Heat; Heat-exposure; Author Keywords: Hexavalent Chromium Stainless Steel; Gas Metal Arc Welding (GMAW); Flux Cored Arc Welding (FCAW); Shielded Metal Arc Welding (SMAW); Welding Fume
CODEN
WEJUA3
CAS No.
18540-29-9; 7440-47-3
Publication Date
20120901
Document Type
Journal Article
Email Address
mjk3@cdc.gov
Fiscal Year
2012
NTIS Accession No.
NTIS Price
Identifying No.
B10152012
Issue of Publication
9
ISSN
0043-2296
NIOSH Division
HELD
Priority Area
Construction
Source Name
Welding Journal
State
WV; CO; IN
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