Assessment of exposure to chemical agents in welding 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 Background Aims and objectives Experimental work Results Recommendations

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) For each substance, the fume concentration (mg m -3 ) below which its limit value is not exceeded is given by: 100 x LV c 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) 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) 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) 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 Fume samples generated by mechanised welding: –semi-mechanised rig used for MMA welding –Kat Gulley GK 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

Welding parameter tests for stainless steel welding

Mean results from welding parameter tests

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

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 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 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 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 its significance for the application of the EH 54 procedure

Effect of dust on Cr content of welding fume

Effect of dust on fume composition

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 –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

EN ISO recommendations for MIG/MAG welding

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