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Safety in the Welding Shop - Coggle Diagram
Safety in the Welding Shop
Arcs
ultraviolet light
burns on the skin
arc eye
spatter.
Hot metal
burns on the skin
spatter
dryness of the eyes.
Filter glasses
BS EN 169, 170, 171.
Fire
rags
inflammable liquids
extinguishers
Fire exit
Cables
Cable size
maximum current
cable length
duty cycle
Mechanical hazards
working platforms
overhead jigs
components - held together by tack welds or untested welds.
Noise
Sources
cooling and extraction fans
electric motors
welding operation
compressors
air tools
carnage and materials handling
exposure
seriously damage hearing
High noise levels
long term exposure to lower levels
decibels (dBs)
less than 80dB-safe without ear protection
115dB being prohibited.
noise reduction
at source if possible
acoustic barriers
Alternative working methods
arranging the workplace
noise level areas
noise protection
ear plugs or ear defenders
Electrical
relatively low voltage
precautions
Do not interfere with the connections on the primary (input) mains supply cable; wiring up the primary cable is for a qualified electricians only.
Check that the casing of the set is earthed. If possible, earth the work by a separate earth cable to avoid hazards from using portable tools or equipment faults.
Do not use portable electric tools which have been damaged; visually check plugs and cable before plugging in.
Check electrode holders, torches and guns regularly to ensure the insulation is satisfactory.
If working more than a few metres from the main switch, provide a local means of disconnection.
If working in damp or sweaty conditions check the OCV of MMA sets and ensure that it is no higher than necessary or the electrodes in use.
Take extra care or use OCV reduction relay. Keep clothes, gloves and shoes dry, so will provide extra insulation.
If welding in damp conditions try to stand on a rubber or board mat.
Most modern welding equipment is DC but old AC MMA sets remain. AC is especially dangerous in wet conditions so care should be taken. AC equipment is often ≥80 OCV, further increasing the risk.
Grinding
hazards
Badly fitted
damaged grinding discs
precautions
fitted by a competent person.
Always check for damage to the disc before use. If any damage is evident do not use. Do not mistake normal wear due to use for mechanical damage.
Always wear shatterproof safety glasses that offer protection to the sides of the eye.
Always use the grinder so that sparks are sent into a safe area. Check for other people in the vicinity.
Never operate a grinder with only one hand.
Gas cylinders
precautions
threads are clean before connecting regulators
use regulators of the correct fitting and type for the gas.
Do not use oil or grease on gas connections
correct cylinder stands
adequate ventilation
Regulators for fuel gases - left hand threads
high pressure
Gas
Oxygen
oxygen enrichment will cause cloth to burn explosively
Acetylene
dissolved in
Fumes and gases
Welding consumables (electrodes, fluxes and gases).
Parent metal.
Low carbon steel
no issues
Manganese steel
Irritant manganese fumes -High manganese (12-14%) steels.
Stainless steel
hexavalent chromium (Cr6)
carcinogenic.
Aluminium
risk of ozone
Copper
Excess copper or zinc fumes
metal fume fever
Zinc
Shivering, headaches, chest tightness and feverishness
Lead
little fume will be generated in normal operation
Alloys containing lead
Not usually welded
Cadmium
Extremely poisonous
Beryllium
Extremely poisonous
Magnesium and its alloys
no fume problem -can be set alight by the heat of welding.-swarf
Surface coating of parent metal (plating, paint).
Materials
Cadmium - anti-corrosion plating
Lead
Zinc - Galvanising
Nickel and copper - undercoat
Paints - contain metallic compounds
Recommended procedure
remove the coating
within 25-100mm of the weld
Degreasing fluid
trichloroethylene
Degreasing fluid can form phosgene.
Air-ozone and oxides of nitrogen can be formed.
ozone
The ultraviolet light of the arc can cause oxygen to re-arrange itself into ozone.
302 to 203
irritating and harmful to the lungs
contact with most solids will cause it to revert to oxygen
Oxides of nitrogen
form nitric and other acids -contact with moisture
lung irritants
Internal combustion engines.
safe when vented to atmosphere
carbon monoxide
Measurement and occupation exposure limits (OELs)
Gases are generally invisible.
using a directly indicating analyser giving almost instantaneous readings of a particular gas
Fume
Fume is measured by drawing a known volume of air through a fine filter: By weighing the paper before and after, the total amount of fume is calculated in milligrams per cubic metre (mg/m3).
Chemical analysis may be used to find the amount of individual constituents, again expressed as mg/m3
Ventilation
Welder posture
clear of the plume of fume
General shop ventilation
general ventilation in a welding shop should remove all fume and gases which escape the local extraction system
Local fume extraction
external nozzle can be placed near the weld to extract all fume and gases
Other protective measures
Fume extractor gun
Special metal arc shielding guns have an extra nozzle outside the normal gas shielding nozzle
Dust respirator or half mask
A simple mask, covering the welder’s mouth and nose is fitted with a disposable filter cartridge.
Air-fed welding helmet
A special welding helmet is manufacturer fitted with a distributor nozzle which allows clean air delivered by a hose to enter the welder's breathing zone,
Breathing apparatus
A compressed air cylinder feeds clean air to a sealed facemask or helmet.
open air
fume and gases
dissipated harmlessly
Recommendations for specific processes
TWI booklet 'The facts about fume'