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Profiling mild steel welding processes to reduce fume emissions and costs in the workplace.

Authors
Keane-MJ; Siert-A; Chen-BT; Stone-SG
Source
Ann Occup Hyg 2014 May; 58(4):403-412
NIOSHTIC No.
20043818
Abstract
To provide quantitative information to choose the best welding processes for minimizing workplace emissions, nine gas metal arc welding (GMAW) processes for mild steel were assessed for fume generation rates, normalized fume generation rates (milligram fume per gram of electrode consumed), and normalized generation rates for elemental manganese, nickel, and iron. Shielded metal arc welding (SMAW) and flux-cored arc-welding (FCAW) processes were also profiled. The fumes were collected quantitatively in an American Welding Society-type fume chamber and weighed, recovered, homogenized, and analyzed by inductively coupled atomic emission spectroscopy for total metals. The processes included GMAW with short circuit, globular transfer, axial spray, pulsed spray, Surface Tension Transfer, Regulated Metal Deposition, and Cold Metal Transfer (CMT) modes. Flux-cored welding was gas shielded, and SMAW was a single rod type. Results indicate a wide range of fume emission factors for the process variations studied. Fume emission rates per gram of electrode consumed were highest for SMAW (~13mg fume g-1 electrode) and lowest for GMAW processes such as pulsed spray (~1.5mg g-1) and CMT (~1mg g-1). Manganese emission rates per gram of electrode consumed ranged from 0.45mg g-1 (SMAW) to 0.08mg g-1 (CMT). Nickel emission rates were generally low and ranged from ~0.09 (GMAW short circuit) to 0.004mg g-1 (CMT). Iron emission rates ranged from 3.7 (spray-mode GMAW) to 0.49mg g-1 (CMT). The processes studied have significantly different costs, and cost factors are presented based on a case study to allow comparisons between processes in specific cost categories. Costs per linear meter of weld were $31.07 (SMAW), $12.37 (GMAW short circuit), and $10.89 (FCAW). Although no single process is the best for minimizing fume emissions and costs while satisfying the weld requirements, there are several processes that can minimize emissions. This study provides information to aid in those choices. Suggestions for overcoming barriers to utilizing new and less hazardous welding processes are also discussed.
Keywords
Workplace-studies; Welding; Welding-industry; Steelworkers; Metal-fumes; Emission-sources; Fumes; Arc-welding; Quantitative-analysis; Gas-welders; Manganese-compounds; Nickel-compounds; Iron-compounds; Industrial-processes; Sociological-factors; Author Keywords: flux-cored arc welding; fume emissions reduction; fume generation rates; gas metal arc welding; manganese generation; nickel generation; welding costs; welding fumes
Contact
Michael J. Keane, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
CODEN
AOHYA3
CAS No.
7439-96-5; 7440-02-0; 7439-89-6
Publication Date
20140501
Document Type
Journal Article
Email Address
mjk3@cdc.gov
Fiscal Year
2014
NTIS Accession No.
NTIS Price
Identifying No.
M022014
Issue of Publication
4
ISSN
0003-4878
NIOSH Division
HELD
Priority Area
Construction
Source Name
Annals of Occupational Hygiene
State
WV; CO
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