Transcript Welding, Cutting and Brazing

Welding, Cutting and Brazing
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Safety Hazards of Welding
 Fire and explosions
 Compressed gases and cylinders
 Confined spaces
 Electrical hazards
 Dangerous machinery
 Trips and falls
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Health Hazards of Welding
 Welding fumes
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and smoke
Heat and sparks
Visible light,
ultraviolet and
infrared radiation
Musculoskeletal
injuries
Noise
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Fire Prevention: Basic Precautions
 Asses the fire hazards
 If object to be welded or cut can’t be easily
moved, remove all fire hazards in vicinity
 If object and fire hazards can’t be moved, use
guards to confine heat, sparks and slag
 If these requirements can’t be met, then
welding shouldn’t be done
 Have fire extinguishers ready for instant use
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Special Precautions: Fire Watch
 Purpose: detect and extinguish smoldering fires
 Required for locations where more than a minor
fire might develop or:
– Appreciable combustible materials closer than 35
feet to operation OR more than 35 feet away, but
easily ignitable by sparks
– Wall of floor openings expose combustible materials
within a 35-radius
– Combustible materials on other side of walls/ceilings
 Maintained for at least 1/2 hour after completion
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Fire Prevention: Welding is
Prohibited in Certain Areas
 Areas not authorized by management
 Buildings with impaired sprinkler systems
 Areas with explosive atmospheres
 Areas where explosive atmospheres may
develop
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Fire Prevention: Used containers
 Make sure used drums
barrels, tanks or other
containers have been
thoroughly cleaned
 Disconnect pipes or
connections to
the container
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Personal Protection: Fall
Protection
 When working at heights
– Use railings, safety belts,
lifelines or other safeguards
– Protect workers below
from falling sparks or slag
 Place welding cables and
other equipment clear of
passageways, ladders or stairways
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Personal Protection: Eye
Protection
 Use helmets, shields and goggles during arc
welding or cutting
 Use goggles or other
eye protection during
gas welding or oxygen
cutting operations
 Shield other from
welding light with an individual booth or
screen, if practical
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Personal Protection: Eye
Protection - Shading Requirments
 Shielded metal arc welding
10
 Gas shielded arc welding (non-ferrous)
11
 Gas-shielded arc welding (ferrous)
12
 Torch Brazing
3 or 4
 Heavy cutting (6 inches & over)
5 or 6
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Personal Protection: Clothing
 Welding gloves, gauntlets and sleeves
 Flame resistant aprons
 High-cut safety boots and leggings
 Shirts: heavyweight, wool, sleeved, collars
buttoned, no pockets
 Pants: no cuffs and long enough to extend
over boots
 For overhead work: shoulder capes, skullcaps,
ear protection
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Personal Protection: Ventilation
 Ensure adequate ventilation prior to working
 Use local exhaust ventilation where needed
 Respirators worn:
– When cancer-causing agents present
– During certain confined space work
 Materials requiring extra precautions: fluorine
compounds, zinc, lead, beryllium, cadmium,
mercury, cleaning compounds, stainless steel
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Before Entering Confined Spaces
 Acquire confined space permit
 Ensure adequate ventilation
– Test before entering for flammable/toxic gases or
oxygen deficiency
– If flammable or toxic gases are present - ventilate
– If ventilation is inadequate, use a respirator
 Disconnect pipes, ducts and power lines
 Leave gas cylinders and welding machines
outside of the confined space
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Confined Spaces
 Attendant must observe the welder and be ready
to execute a pre-planned emergency rescue plan
 If arc welding is suspended for a period of time:
– Remove electrodes from holders
– Disconnect machines from power sources
 If gas welding is suspended for a period of time:
– Close the torch valves
– Shut off the gas supply to the torch
– Remove the torch and hose, if practical
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Cylinder Storage
 In a well-ventilated, dry, location >20 ft away
from highly combustible materials such as oil
 Away from sources of heat and ignition
 Away from high traffic areas and exits
 Stored in compatible groups
– Oxygen and Acetylene: separated by 20 feet or a
5-foot wall with 1/2-hour fire rating
 In upright position with valve protection caps
on and secured with straps or chains
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Cylinder Handling
 Never work with unidentified cylinders
 Refer to MSDS for specific hazards, special
handling instructions, emergency response
and first aid information
 Inspect cylinders for damage prior to work
 When transporting:
– Secure to wheeled hand cart with the
regulator removed
– Never use valve caps to lift the unit
– Don’t drop or bang
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Cylinder Handling (cont’d)
 Valve protection caps must always be in place
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when not in use - empties included
If cylinder must be left unattended, close
cylinder valve and shut down system
Keep cylinder in an upright position at
all times
Keep cylinders and valve caps free from oil
or grease
Mark work areas when finished work
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Placement of Cylinders During Use
 Cylinders must be placed where sparks, hot
slag or flames can’t reach them
 If that’s not possible, use fire-resistant shields
 Keep cylinders away from electrical circuits
or objects used for grounding
 Cylinders must be placed outside any
confined space
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To Begin Work
 “Crack” the cylinder valve
 Ensure regulators are compatible, clean and
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in good condition before attaching them
Make sure hoses and connections are secure
When opening the cylinder valve, stand to the
side and open s-l-o-w-l-y.
Keep any vendor-supplied keys in place
Keep the valve within easy reach
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Purge Hoses Prior to Lighting
 First, acetylene
– Open acetylene
cylinder valve 3/4 turn
– Open torch valve
1/4 turn
– Adjust to working
pressure with regulator
screw
– Close torch valve
 Then, oxygen
– Open oxygen cylinder
valve fully (slowly)
– Open torch valve
1/4 turn
– Adjust to working
pressure with regulator
screw
– Close torch valve
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Lighting and Shutting the Torch
 To light torch:
 To shut off torch:
– Reopen acetylene
torch valve
– Light with friction
lighter:
• Never matches
• Never cigarettes
– Open oxygen 1/4 turn
and adjust flame
– Close torch valves:
acetylene then oxygen
– Close cylinder valves:
acetylene then oxygen
– Open both torch valves
to release pressure
– Shut off regulator
adjusting handle
– Close torch valves
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For Safe Use of Acetylene
 Never used at pressure in excess of 30 psi
absolute or 15 psi gage
 Never open acetylene valve more than
1 1/2 turns.
 Never use copper fittings or connections
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Arc Welding and Cutting
 Ensure the work area is dry
 Double-check the grounding
 Check connections to the machine
– Make sure work lead is firmly attached
– Keep metal clamps free from debris
 Never use cables with splices within 10 feet
of the holder
 Replace cables with damaged insulation or
exposed bare connectors
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Arc Welding and Cutting (cont’d)
 Spread out cables
 Never coil cables around your body
 Never strike an arc on a gas cylinder
 Never change polarity switch during operation
 If work must be stopped, disconnect power
source and remove electrodes
 Store holders where they can’t make
unwanted contact
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Summary
 Safety and health hazards = special precautions
 Fire prevention
 Personal Protection
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Fall safety
PPE
Confined spaces
Ventilation
 Use of compressed gas cylinders
 Safe welding procedures
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