Foundations of Agriculture
Auto body and Restoration Repairs on small parts Portable welding OAW was the first type of portable welder
Acetylene is mixed with oxygen in correct proportions and ignited. The flame becomes very hot (approx. 6,300 F), which allows metals to be joined by a pool of molten base metal. A filler rod can be utilized to add strength to the weld. The filler rod must be of similar composition to the base metal
Constructed of seamless drawn steel Hydro-tested to 3360 PSI
Cylinder Pressure 2,200 PSI @ 70 F Bursting disc (AKA rupture disc)- safety device to relieve pressure in the cylinder if the pressure becomes too great. One time use
1. The valve should ALWAYS be opened by hand. NOT with a wrench 2. Turn valve on SLOWLY to permit a gradual pressure load on the regulator 3. Open the valve as far as the valve will turn for full pressure
244 ft 3 122 ft 3 80 ft 3
Mixture of calcium carbide and water Colorless gas that has a nauseating odor (garlic odor) Stored at 15 PSI (anything over that becomes extremely unstable) Acetone is used in the tank as a stabilizer for the acetylene
Fusible plug- used as a pressure relief device on acetylene cylinder. Located on the bottom of the cylinder
Only open the cylinder valve ¼ turn This allows for quick shut-off in the event of an emergency
Flashback arrestors- prevent a flashback from the torch from reaching the inside of the acetylene cylinder and causing an unsafe situation (explosion or fire)
Purpose: to mix the acetylene and oxygen to the correct proportions and permits the mixture to flow to the end of the tip where it is burned.
The reduce cylinder pressure to the required working pressure The regulators produce a steady flow of gas under varying cylinder pressure.
IMPORTANT RULE Make sure the adjusting screw is released (turned out) before the cylinder is opened
Always check the adjusting screw before the cylinder valve is turned on NEVER use oil on a regulator for safety. If it is sticky, use soap or glycerin to lubricate the adjusting screw Do not try to interchange the oxygen and acetylene regulators
Green Hose Right-handed threads
Red Hose Left-handed threads Notched
Used for igniting the OAW torch
OAW produces light rays of great intensity and heat rays which could hurt the naked eye. Use either #4, #5, or #6 shades (full face shield w/ safety glasses) depending on the size of torch being used
1. Chain Cylinders- secure tightly against wall or cart.
2. Crack Cylinder Valves- Particles of dust frequently collect in the outlet nozzle of the cylinder valve, which would cause damage to a regulator. Crack open the valve for an instant to clean it out.
3. Attach Regulators- connect oxygen regulator (right-hand threads) and connect acetylene regulator (left-hand threads) with a wrench DO NOT OVERTIGHTEN
4. Connect hoses to regulators- connect green hose to oxygen (right-handed threads) and red hose to acetylene (left-handed threads)
5. Connect hoses to torch knobs- green hose to right knob; red hoses to left knob
6. Testing for leaks- apply soapy water with a brush on all connection points. 7. Listen for hissing noises and look for bubbles
8. Select proper tip- select proper tip according to thickness of metal being welded
Lighting the torch Open acetylene valve and light with striker, turn up gas until you have a clean flame. Slowly turn on oxygen until you get desired (neutral) flame
Neutral Flame- Turn oxygen on until feather disappears inside cone. This flame is an approximate 1:1 mix of acetylene and oxygen. When welding, the metal will flow smoothly like syrup, with very few sparks, clean and clear.
Oxidizing Flame- Excess amount of oxygen. Shorter flame and the color changes to a purpleish hue. Flame has a hissing noise and when welding metal, there are many sparks and white foam or scum forms on the surface.
Carburizing Flame- Consists of a slight excess of acetylene and a feathery edge is present outside of middle cone. Metal has a tendency to boil and after it has been cooled, the surface is pitted and brittle.
The flame goes out with a loud POP Cause: The tip touched the metal, overheating of the tip, or there is an obstruction in the tip Remedy: Clean tip
Is a condition that results when the flame flashes back inside the torch and burns with a shrill hissing or squealing noise. Cause: Improper function of needle valve, clogged tip or incorrect pressure Remedy: investigate problem before relighting
1. Close acetylene torch knob 2. Close oxygen torch knob 3. Turn off cylinder valves 4. Open torch knob and drain hoses 5. Release adjusting screw on regulators
A. Acetylene Regulator
B. Safety Bracket
C. Acetylene Cylinder
D. Acetylene Hose
E. Oxygen Regulator
F. Oxygen Cylinder Valve
G. Torch Body
H. Bursting Disc
I. Oxygen Torch Knob
J. Acetylene Torch Knob
K. Oxygen Cylinder
L. Oxygen Hose
M. Acetylene Cylinder Cap
N. Oxygen Cylinder Cap
O. Fusible Plug
P. Acetylene Valve Wrench