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Assessment of exposure to chemical agents in w elding fume

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

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  1. 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)

  2. Overview • Background • Aims and objectives • Experimental work • Results • Recommendations

  3. 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

  4. 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)

  5. 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

  6. 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

  7. 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

  8. 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

  9. Welding parameter tests for stainless steel welding

  10. Mean results from welding parameter tests

  11. Effect of voltage on fume composition for different wire diameters in MAG welding of stainless steel

  12. 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

  13. 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 %

  14. 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 %)

  15. 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

  16. Effect of dust on Cr content of welding fume

  17. Effect of dust on fume composition

  18. 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

  19. EN ISO 15011-4 recommendations for MIG/MAG welding

  20. 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

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