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Valerie WeihmanRock - Friday, September 9, 2011 - 11:45pmWelding gas welding | oxy-acetylene | welding | welding torch
Here is a step-by-step guide for setting up oxyacetylene equipment. It is a really handy reference, good refresher and also a confidence-builder for new users.
First check over the condition of the equipment. Are the cylinders chained to the cart? Are the torch valves closed? Are the hoses in good condition?
Check that the adjusting screws on each regulator are loose. Loose means turned out counterclockwise. This releases the pressure on the diaphragm.
Open up the acetylene cylinder valve slowly so that it is one-half to one full turn open (one full twist of the wrist). The needle on the high pressure gauge should now indicate the amount of acetylene pressure in the cylinder. If no pressure is indicated - stop at this point.
Screw in the adjusting screw on the acetylene regulator (clockwise) until the needle on the low pressure gauge indicates the desired working pressure*.
Now bleed out the acetylene hose and check the actual working pressure* at the same time. To do this, open up the acetylene valve on the torch. Let the gas flow out of the torch for a few seconds. While the torch valve is still open, look at the low pressure gauge and readjust to the desired working pressure*. Close the torch valve.
Open up the oxygen cylinder valve stem just a crack. Once the needle on the high pressure gauge has stopped, open up the valve all the way. This back-seats the valve. All high pressure cylinders have these back seating valves. Fuel does not.
Screw in the adjusting screw on the oxygen regulator (clockwise) until the needle on the low pressure gauge indicates the desired working pressure*. Note that this gauge is usually calibrated in 5-pound increments, differing from the acetylene regulator low pressure gauge.
Now check the actual working pressure* of the oxygen in the same way as was done for the acetylene. If you screw it in too far and obtain too much pressure, be sure to open the torch valve before readjusting the pressure.
(*) Working pressure= this varies with the size of the hole in the torch tip. Usually 5psi Oxy, 5psi Acetylene works fine. Small tips 3 and 3. Larger tips used for heating (rosebud) use much more. Best to use a reference for pressure set up)
Lighting the torch
Open the acetylene torch valve about one-quarter turn. Light the acetylene with a spark from a “striker”. Do not use matches or a butane lighter.
Adjust the flame, using the acetylene torch valve until the flame has just lost its “smoky” quality. If the flame “blows out” or blows away from the tip of the torch, the torch valve is too far open. Close the valve a bit and then slowly reopen.
With the proper shade gas welding lens (#3-#7 depending upon torch tip size. Usually #5 fine) over your eyes, slowly open up the oxygen torch valve. A small, pointy flame very close to the torch tip will appear. This is called the ‘inner cone’. At the same time, a distinct, blue flame will begin to appear at the end of the flame. Continue to slowly open up the oxygen torch valve until the distinct blue flame has just shrunk to the same size as the inner cone. This is the proper welding flame called a neutral flame.
When you are welding, the area right outside of the blue cone is your "tool". Do not push the tip of flame "cone" into metal.
Proper shut-down of the cylinders
Extinguish the flame by turning off the acetylene torch valve first. Then turn off the oxygen torch valve. Close them gently because they are needle-valve and their seats can be easily damaged. It is important to do the acetylene first and then the oxygen. If the reverse order is used, carbon deposits are left in the torch every time the torch is turned off. For very large torch tips, some people turn the torch off in the incorrect manner because of the loud pop the torch sometimes makes. (Victor book is incorrect)
Close the acetylene cylinder valve with a firm hand. Close it to the right (clockwise).
Open the acetylene torch valve again. Watch the needles on both of the acetylene cylinder gauges. When they are both at zero, gently close the torch valve again. The acetylene has now been properly bled from the system. Loosen adjusting screw.
Close the oxygen cylinder valve. Since this valve was previously opened up all the way, it takes some time to get the valve fully closed. Close with a firm hand.
Open the oxygen torch valve. Watch the needles on the oxygen regulator valves. When both of the valves are at zero, close the torch valve again. The oxygen has now been properly bled from the system. Loosen adjusting screw.
Wrap the hoses around the handle part of the cart. If the torch tip is still hot, be careful that it does not touch any part of the hoses. Don’t wrap the hoses around the cylinders. If the hoses are around the cylinders, it is not easy to tell if the cylinders are properly chained.
Note: The cylinders should be completely shut down in this manner whenever the operator leaves the room. If you are the last person in the area that work day, be sure to check that other cylinders are shut down properly. If you come upon cylinders that are not shut down properly, first screw in the adjusting screw until the low pressure side of that regulator indicates pressure. Then open up the corresponding torch valve and wait until the needles drop to zero. Then loosen the adjusting screw again. Sometimes this happens if the cylinder valve stem was not closed tightly enough - check that too.