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The Basics of Oxyacetylene Gas Welding Tanks and Equipment

The Basics of Oxyacetylene Gas Welding Tanks and Equipment

Gas Cylinders: Oxygen & Acetylene

Oxygen is pressurized in tanks at approximately 2220 pounds per square inch (PSI). Oxygen tanks have a valve and are always covered by a safety cap (by which you should never lift the tank). Oxygen tanks include a safety value to relieve pressure, should the tank become over heated. Always store and transport oxygen tanks upright.

Acetylene is an extremely unstable gas, and cannot be pressurized above 15 psi. Therefore, to pressurize acetylene to 225 psi (the pressure required to bottle the gas), a tank is filed with porous materials to stabilize the gas, and the acetone absorbs the gas. Acetylene tanks include fusible plugs that will melt in case of fire, allowing the gas to escape slowly, avoiding an explosion. Always store and transport acetylene tanks upright, if you use a tank in tilted position, you will destroy the regulator and hoses you connect to the tank.

When transporting tanks, always make sure they’re secured with a strap or restraint to ensure they don’t fall over.

All tanks include a valve to control the flow of gas, and a handwheel or wrench is used to open and control the valve. Oxygen valves are backseating, and should always be fully open while in use, because backseating valves are leak-proof when fully open or fully closed. Acetylene tank valves should never be opened more than ¾ to 1 ½ of a turn. If the acetylene tank is open too little, the pressure will be insufficient and may lead to a Backflash. If the valve is open too much, you will have a difficult time closing the valve in an emergency situation.

Tanks also include Check Valves and Flashback Arrestors to prevent flashbacks. If gas pressure in the torch exceeds the pressure in the hose, a spring closes the valve to prevent backflow. If, however, the flashback does occur, the Check Valve will need to be replaced. The Flashback Arrestor is and additional measure used to prevent burning oxygen from flashing back up the hose and into the tank, which can cause an explosion.

Pressure Regulators and Gauges, Hoses and Fittings

A pressure regulator reduces the flow of gas from the tank, and comes in one and two stage arrangements, with a two stage regulator affording you much greater control, and is the preferable set-up. The regulator adjustment screw turns clockwise to increase the pressure and counter-clockwise to decrease the pressure. When the adjustment screw is completely loose, the regulator is completely “backed out” and the flow of gas is off. This is how the tank should be left when you welding job is complete.

Hoses are made of flexible rubber tubing, connecting the flow of gas from the tank to the torch handle. The oxygen hose is green and the acetylene hose is red. Hoses come in dual arrangements that pair oxygen and fuel together in a double hose (two connected side-by-side) , and are generally more convenient. Hoses are relatively fragile and should be kept off the floor and out of traffic areas, out of the weld area away sparks, and away from sunlight and chemical fumes, as all of these issues can damage and weaken hoses.

A fitting connects a hose to a regulator at the tank at one end, and connects a hose to torch a handle at the other end. The fuel hose fitting tightens to the left and is grooved, while the oxygen hose fitting tights to the right and has no groove. Fitting are made of brass, a soft metal that will be damaged if you force tighten it with a wrench. Fittings should always be hand tightened first, and then gently firmed up with a wrench to ensure proper seating.

Torch Handle and Torch Tip

The torch handle is where the oxygen and acetylene are mixed and the flow of gas emitted is controlled. The torch handle includes the valve, body and mixing chamber.

The tip, just as it sounds, is at the very tip of the torch handle, and is the point at which gas is emitted from the torch. The tip includes a number of holes to preheat the gas fuel, in addition the main center hole from which oxygen is emitted. Torch tip sizes vary, and are selected depending upon the thickness of the metal being welded.



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