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Please read this before using presentation

Please read this before using presentation. This presentation is based on content presented at the 2008 Mines Safety Roadshow held in October 2008

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  1. Please read this before using presentation • This presentation is based on content presented at the 2008 Mines Safety Roadshow held in October 2008 • It is made available for non-commercial use (e.g. toolbox meetings) subject to the condition that the PowerPoint file is not altered without permission from Resources Safety • Supporting resources, such as brochures and posters, are available from Resources Safety • For resources, information or clarification, please contact: ResourcesSafety@docep.wa.gov.au or visit www.docep.wa.gov.au/ResourcesSafety

  2. Toolbox presentation: Arc welding hazards and safeguards – fumes and gases

  3. Electric arc welding 3

  4. Welding hazards • Electric shock • Radiation • Burns • Heat stress • Fire • Explosions • Asphyxiation • Fumes and gases 4

  5. Hazards of fumes and gases What do you know about … your welding processes? composition of the fumes you work in? how well you are being protected from any toxic effects? Fume is general term describing mix of airborne particles 5

  6. Fumes and gases produced by welding All types of welding will produce metal fumes Shield metal arc welding (SMAW) and manual metal arc welding (MMAW) Fumes Gas metal arc welding (GMAW) and metal inert gas (MIG) Ozone Carbon monoxide and other gases (depending on shielding gas used) Gas tungsten arc welding (GTAW) and tungsten inert gas (TIG) Ozone Carbon monoxide and other gases (depending on shielding gas used) UV radiation (more produced than in SMAW) Plasma arc welding (PAW) Gases Flux cored arc welding (FCAW) Fumes 6

  7. Metal composition Stainless steel contains: iron nickel chromium manganese Mild (carbon) steel contains: iron generally contains more manganese than other metals 7

  8. CONTAM database statistics 23% of people exposed to welding fumes exceed adjusted exposure standard (ES, based on 8 hr shift) 43% of samples that exceed the adjusted ES are at least two times over ES According to Journal of Occupational and Environmental Hygiene (2007), 72% of boilermakers exceed ES 8

  9. Health effects of welding fumes Metal fume fever Acute flu-like respiratory illness Siderosis Occupational lung disease from inhalation of iron oxide fumes Toxic metal poisoning E.g. cadmium, beryllium Lung cancer Association with stainless steel (chromium and nickel) fumes only ‘Welder’s disease’ Manganism – collection of symptoms resulting from excessive manganese exposure Also called ‘Parkinson’s syndrome’ because it resembles Parkinson’s disease 9

  10. Health effects of welding gases Carbon monoxide Affects blood’s ability to carry oxygen Ozone and nitrogen oxides Irritate nose, throat, eyes, ears and lungs Nitrogen oxides can cause fluid in the lungs 10

  11. Control measures - elimination Eliminate need for welding Buy new equipment Metal coatings add to the fumes produced Safely remove rust inhibitors, paints, degreasers or other coatings before welding begins (band 20-25 mm to be removed each side of weld line) 11

  12. Control measures - substitution Change welding consumables (main contributor to fumes) Avoid wires, electrodes, fluxes with high concentrations of hazardous substances – nickel, chromium, manganese, cadmium, lead, beryllium Substitute lithium silicate or organic binder for sodium or potassium silicates – reduces hazardous chromium VI content in fumes during stainless steel welding Change welding processes Least to most fumes – SAW, GTAW, GMAW, MMAW, FCAW Change shielding gases Fumes reduced by about 20% when mixture of argon and carbon dioxide used instead of carbon dioxide Decrease voltage Produces less fumes 12

  13. Control measures – engineering Use local exhaust ventilation (LEV) Keep exhaust extractions as close to fume source as reasonably practicable Position duct in line with fumes’ natural direction of movement Effective LEV needs 0.5 m/s minimum air velocity Most gas shields can handle air velocity of 2 m/s around weld zone Fixed installations – side- or down-draft benches, partially or completely enclosed booths Portable installations – movable hoods attached to flexible ducts Fume extractors attached to welding gun – can capture 95% of welding fumes 13

  14. Down draft benches Down draft benches help to prevent fumes from passing through the welder’s breathing zone 14

  15. Enclosed booth Extraction via exhaust system from roof Local exhaust ventilation also needed, to direct plume away from welder’s breathing zone Offer noise protection 15

  16. Portable exhaust ventilation 16

  17. Control measures – engineering (continued) Use general ventilation Must be well designed so clean air flows past workers, contaminated air drawn away from workers Not as effective as local exhaust ventilation Should only be used for low toxicity substances Fans will dilute and help to move fumes along (consider where to!) 17

  18. Control measures - administrative Good work practices can reduce exposure to fumes Keep face out of the line of plume Do not remove face shield until plume has dispersed Remove surface coatings before welding begins Have work clothes washed on-site (restrict spread of contaminants) Reduce duration and frequency of task Limit time any one welder is exposed to high fume concentrations Promote no-smoking policy Smoking increases susceptibility to adverse health effects from welding fumes 18

  19. Control measures – administrative (continued) Training How to recognise harmful substances (metal coatings, degreasers, rust inhibitors) Use of MSDSs to identify presence of metals such as cadmium, nickel, chromium, lead, beryllium and manganese Ways to reduce overall fume production Ways to reduce fume exposure Care and maintenance of PPE Consult with ventilation experts and colleagues Monitor and review processes 19

  20. Control measures – PPE (respiratory) Respirators should be worn during all welding processes Level of respiratory protection required depends on amount of time spent welding toxicity of fumes whether gases may also be present ventilation of work area Protection in accordance with AS/NZS 1715 and AS/NZS 1716 20

  21. Control measures – PPE (respiratory) (continued) Class P3 respirator protects against all particulates including highly toxic material (e.g. beryllium, cadmium) Combination of particulate and gas filters may be necessary Welding aluminium, galvanised steel or stainless steel requires added protection (e.g. powered air purifying respirator, additional ventilation) Respirators with one filter to each side fit better under welding shields than respirator with only one filter at the front 21

  22. Powered air purifying respirators Powered air purifying respirators (PAPR) provide better protection and are more cost effective in the long term than disposable respirators 22

  23. Summary of hazards from fumes and gases All welding processes pose a health risk, some more than others Best way to protect yourself from risks is through: avoiding more hazardous substances, where practicable adequate ventilation exhaust systems good work practices being familiar with the materials you are using (read the MSDS) wearing appropriate, well-fitted and maintained PPE Outdoors or open work space: general ventilation Limited work space: local exhaust ventilation Confined space: respirator, local exhaust ventilation, communication strategy, rescue plan If unsure, consult a hygienist and avoid fumes 23

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