Construction Tech
OA Welding
Review
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Never use oil on oxygen connections
Never force connections
Fasten cylinders to wall or cart before cracking valve
Red hose = left hand threads = fuel gas
Check connections before using
Use shade 3-5 lenses
Use friction lighters, not matches
Check pressures carefully, acetylene cannot be set above 15
Keep cylinders away from fire
Never use leaky cylinders
Open acetylene only ½ to 1 turn
Drain valves and remove pressure from regulators when done
Do not drag flame across hoses or cylinders
Replace cracked hoses
Never attempt to transfer gas from one cylinder to another
Be aware of combustibles in area
Never do any welding or cutting on containers that have held a flammable substance
Galvanized metal is highly toxic. Do not weld or cut without excellent ventilation
Ventilate area in which you are welding
Do not relight flame in pocket or small confined space
Wear appropriate clothes for welding or cutting
Store extra cylinders away from work area
Store cylinders upright, always
Be ready to put out a fire!
Shut off acetylene first, then oxygen (to blow out flame)
Be comfortable, but safe
Keep flashbacks or backfires at a minimum by proper maintenance of equipment. Backfires are
caused by:
a.
dirty tips
b.
improper gas pressures (low)
c.
leaks or loose connections
d.
overheating the metal and tip
e.
luminous cone in pool
Flashbacks (burning behind mixing chamber) are caused by:
a.
loose tip or nozzle
b.
dirty or damaged seat
c.
cracked or distorted torch head
1) Turn on unit
a) Check torch valves are off
b) Adjusting screw is loose
c) Gages are zeroed
d) Adjusting screw is pointed away from people
e) Turn on oxygen all the way.
f) Turn on acetylene ½ turn
g) Adjust oxygen screw to 25 psi on working pressure gage
h) Adjust acetylene to 5 psi on working pressure gage
i) Turn on oxygen torch valve all the way
Parts:
Acetylene (C2H2) is produced from calcium carbide and water.
At 70 degrees F:
Acetylene is stored in cylinders of approximately 100 or 60 cu ft. The cylinder is packed with a
porous material. Usually asbestos and balsa wood is saturated with acetone, because acetylene can never
be stored in a free state. A cylinder will be packed to 250 psi. The acetone is heavier, thus settles to
bottom. None is lost through the valve, unless cylinder has been laid on its side.
Oxygen is stored in cylinders of approximately 244 or 122 cu ft. (2200 psi at 244), as temperatures
decrease, pressures do also. As temperatures rise, so do pressures.
Cylinder safety devices:
Acetylene:
fusible plugs
Oxygen:
bursting disks
Regulators:
Gages:
Working and cylinder
Torch body and parts:
Three Flames:
Oxidizing
Neutral
Carburizing
Set up and operate equipment:
2) Secure cylinders
3) Crack cylinder valves
4) Attach regulators
5) Connect hoses to regulators
6) Blow out hoses
7) Connect hoses to blowpipe
8) Attach tip
9) Turn on unit
a) Check torch valves are off
b) Adjusting screw is loose
c) Gages are zeroed
d) Adjusting screw is pointed away from people
e) Turn on oxygen all the way.
f) Turn on acetylene ½ turn
g) Adjust oxygen screw to 25 psi on working pressure gage
h) Adjust acetylene to 5 psi on working pressure gage
i) Turn on oxygen torch valve all the way
10) Test for leaks using soapy water (it will bubble)
11) Light the torch
How do you run puddle?
How do you run a bead?
How do you cut metal?