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Assessment of exposure to chemical agents in w elding fume. Alan Howe , Stephen Bradley, Ken Chung and Monica Martinez (HSL), Graham Carter (TWI), and Christine Northage and Roger Sykes (HSE). Overview. Background Aims and objectives Experimental work Results Recommendations.

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assessment of exposure to chemical agents in w elding fume

Assessment of exposure to chemical agents in welding fume

Alan Howe, Stephen Bradley, Ken Chung and Monica Martinez (HSL), Graham Carter (TWI), and Christine Northage and Roger Sykes (HSE)

overview
Overview
  • Background
  • Aims and objectives
  • Experimental work
  • Results
  • Recommendations
background 1
Background (1)
  • Welding fume
    • large number of workers exposed in many industries
    • wide range of processes and materials
    • 5 mg m-3 limit value for welding fume
  • Welding fume containing hazardous substances
    • measurement of exposure to individual components of the fume
    • EH 54 method of applying a control limit based on the chemical composition of the fume
background 2
Background (2)

For each substance, the fume concentration (mg m-3) below which its limit value is not exceeded is given by:

100 x LVc

where LV is the limit value for the substance (mg m-3) and c is its concentration in the fume (% m/m) from MSDS data

The control limit is lowest value unless this is above the welding fume limit value (5 mg m-3)

background 3
Background (3)

For the EH54 method to work:

  • Welding fume composition must not be significantly influenced by welding parameters (current, voltage etc)
  • MSDS data must be both accurate and complete
  • Other airborne particles must not interfere
aims and objectives 1
Aims and objectives (1)
  • To investigate the effect of welding parameters on the chemical composition of welding fume and define test conditions for generating future MSDS data
  • To assess the reliability of current MSDS data on the chemical composition of welding fume
aims and objectives 2
Aims and objectives (2)
  • To determine whether dust from welding-related operations can significantly influence the chemical composition of airborne particles to which a welder is exposed
  • To generate the information necessary to develop a European and International Standard on fume data sheets
experimental
Experimental
  • Fume samples generated by mechanised welding:
    • semi-mechanised rig used for MMA welding
    • Kat Gulley GK 171-90 traverse used for MAG and FCAW
  • Analysis
    • X-ray fluorescence spectrometry (XRFS) and/or inductively coupled plasma atomic emission spectrometry (ICP-AES) for metal content
    • spectrophotometry for hexavalent chromium
    • ion selective electrode (ISE) for fluoride
slide11
Effect of voltage on fume composition for different wire diameters in MAG welding of stainless steel
welding parameter test results
Welding parameter test results
  • Repeatability and reproducibility of measurements were typically better than ± 5 %
  • Voltage was the parameter exerting the greatest effect on welding fume composition
  • Variation in fume composition with welding parameters was fairly small, typically < 20 % overall
  • Results were used to make preliminary recommendations for future generation of welding fume composition data
audit of current msds data
Audit of current MSDS data
  • Test samples were produced by MMA, MAG and FCAW welding using stainless steel, nickel alloy, mild steel, cast iron, hardfacing alloy, copper alloy, nickel alloy and aluminium alloy consumables
  • Measured values were compared with MSDS data for each constituent of the welding fume
  • The % measured values v MSDS data were typically in the range 70 % to 140 %, with an average of around 100 % and an average relative standard deviation of around 30 %
msds audit findings
MSDS audit findings
  • Fume composition data given on MSDSs does not exhibit an overall bias %
  • The average RSD for % measured values v MSDS data was considerably higher (30 %) than variability in fume composition found in the welding parameters study (15 %)
  • Reproducibility of MSDS fume composition data could be greatly improved (perhaps to ± 10 %)
field tests
Field tests
  • Dust from welding-related operations, e.g. grinding, can cause the chemical composition of airborne particles to which a welder is exposed to vary from that of the welding fume
  • Field tests were carried out to assess the magnitude of this effect and itssignificance for the application of the EH 54 procedure
recommendations
Recommendations
  • Fume composition data on MSDSs should
    • be determined by analysing fume collected under the test conditions recommended in the proposed European and International Standard EN ISO 15011-4
    • should include all components of industrial hygiene significance
    • should give full details of the test conditions
  • The EH 54 method should be retained, but the findings of this work should be taken into account when the it is revised
acknowledgements
Acknowledgements

Thanks to:

  • Bohler, Corewire, Elga, ESAB, Lincoln, Metrode, Murex, Oerlikon, Rigby Maryland and SAF and UTP for providing the welding consumables for the tests
  • Graham Carter, TWI, for his invaluable technical input
  • Colleagues at HSL
  • Chris Northage and Roger Sykes, HSE, for funding the work