Profiling stainless steel welding processes to reduce fume emissions, hexavalent chromium emissions and operating costs in the workplace

Details

• Personal Author:
  Chen BT ; Keane M ; Siert A ; Stone S
• Description:
  Nine gas metal arc welding (GMAW) processes for stainless steel were assessed for fume generation rates, fume generation rates per g of electrode consumed, and emission rates for hexavalent chromium (Cr6+). Elemental manganese, nickel, chromium, iron emissions per unit length of weld and labor plus consumables costs were similarly measured. Flux-cored arc welding and shielded metal arc (SMAW) processes were also studied. The objective was to identify the best welding processes for reducing workplace exposures, and estimate costs for all processes. Using a conical chamber, fumes were collected, weighed, recovered and analyzed by inductively-coupled atomic emission spectroscopy for metals, and by ion chromatography for Cr6+. GMAW processes used were Surface Tension Transfer, Regulated Metal Deposition, Cold Metal Transfer, short-circuit, axial spray, and pulsed spray modes. Flux-cored welding used gas shielding; SMAW used E308 rods. Costs were estimated as dollars per m length of a ¼ in (6.3 mm) thick horizontal butt weld; equipment costs were estimated as ratios of new equipment costs to a 250 ampere capacity SMAW welding machine. Results indicate a broad range of fume emission factors for the processes studied. Fume emission rates per g of electrode were lowest for GMAW processes such as pulsed-spray mode (0.2 mg/g), and highest for SMAW (8 mg fume/g electrode). Emission rates of Cr6+ ranged from 50 to 7800 µg/min, and Cr6+ generation rates per g electrode ranged from 1 to 270µg/g. Elemental Cr generation rates spanned 13 to 330µg/g. Manganese emission rates ranged from 50 to 300µg/g. Nickel emission rates ranged from 4 to140 µg/g. Labor and consumables costs ranged from $3.15 (GMAW pulsed spray) to $7.40 (SMAW) per meter of finished weld, and were measured or estimated for all 11 processes tested. Equipment costs for some processes may be as much as 5 times the cost of a typical SMAW welding machine. The results show that all of the GMAW processes in this study can substantially reduce fume, Cr6+, manganese and costs relative to SMAW, the most commonly used welding process, and several have exceptional capabilities for reducing emissions. [Description provided by NIOSH]
• Subjects:
  Chemistry Metals Occupational Health Risk Assessment Risk Factors Safety Welding Workplace
• Keywords:
  Arc-welding Author Keywords: Welding Fumes Chemical-properties Emission-sources Exposure-levels Flux-cored Arc Welding Fume Emission Factors Fume Generation Rates Gases Gas Metal Arc Welding Hexavalent Chromium Manganese Generation Rates Metal-compounds Metallic-compounds Nickel Generation Rates Risk-factors Stainless-steel Steel-compounds Welding-equipment Welding-industry Welding Costs Work-environment Workers

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• ISSN:
  1545-9624
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  Colorado ; OSHA Region 3 ; OSHA Region 8 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-8
• Volume:
  13
• Issue:
  1
• NIOSHTIC Number:
  nn:20046589
• Citation:
  J Occup Environ Hyg 2016 Jan; 13(1):1-8
• Contact Point Address:
  Michael Keane, National Institute for Occupational Safety and Health, Health Effects Laboratory Division, 1095 Willowdale Rd. Morgantown, WV 26505
• Email:
  mjk3@cdc.gov
• CAS Registry Number:
  Chromium (CAS RN 7440-47-3) ; Chromium(6+) (CAS RN 18540-29-9) ; Iron (CAS RN 7439-89-6) ; Manganese (CAS RN 7439-96-5) ; Nickel (CAS RN 7440-02-0)
• Federal Fiscal Year:
  2016
• NORA Priority Area:
  Construction
• Peer Reviewed:
  True
• Source Full Name:
  Journal of Occupational and Environmental Hygiene
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:9de6f8fa12c64cae246b81ae060d44f3860bd55bc05109279a3e4aea622bfef49078270be481880e18597cb7e1e9b6737ad94958a02d05aa59e91ef29d0e45b7
• Download URL:
  https://stacks.cdc.gov/view/cdc/201600/cdc_201600_DS1.pdf
• File Type:
  [PDF - 1006.88 KB ]