Department of Consumer and Employment Protection Resources Safety 1 Please read this before using...

1Department of Consumerand Employment Protection Resources Safety

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:[email protected]

or visitwww.docep.wa.gov.au/ResourcesSafety

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

Department of Consumerand Employment Protection Resources Safety

Electric arc welding

3


Welding hazards

Electric shock

Radiation

Burns

Heat stress

Fire

Explosions

Asphyxiation

Fumes and gases

4


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


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


Metal composition

Stainless steel contains: iron nickel chromium manganese

Mild (carbon) steel contains: iron generally contains more manganese than other metals

7


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


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


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


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


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


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


Down draft benches

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

14


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


Portable exhaust ventilation

16


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


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


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


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


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


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


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

Department of Consumer and Employment Protection Resources Safety 1 Please read this before using...

Documents

Transcript of Department of Consumer and Employment Protection Resources Safety 1 Please read this before using...