Smoke Wrench
We recently got our grimy hands on a torch and regulator set from the Eastwood Co. A quick stop at our local Airgas supplier and we were in business for some gas welding. An oxyacetylene kit is essential for anyone who works on cars on a regular basis. A word of caution, though: Acetylene is highly flammable. Use it improperly, and you are asking for big trouble. Here's the safe way to light a torch.
 Open the valve on the acetylene...  Open the valve on the acetylene bottle 1 turn, then open the oxygen bottle fully. |  Like regulators for inert...  Like regulators for inert gas welding, oxy/gas regulators have two gauges: The high pressure gauge reads bottle pressure; the low pressure gauge reads gas pressure between the bottle and the torch. Adjust the acetylene and oxygen regulators to read about 3 to 4 psi. If you're using a cutting tip, you'll need more oxygen pressure-about 20 to 25 psi, but the acetylene remains the same. Also note that these pressures can vary depending on the size of the tip you're using and the thickness of the material you're welding. These numbers are good for most mild steel sheetmetal, though. |  Crack open the valves on the...  Crack open the valves on the torch handle briefly to clear any dirt or debris that may be lodged in the torch, then open the acetylene valve 1/8 to 1/4 turn. Keep the oxygen valve closed while lighting the torch. |
 Hold the striker in front...  Hold the striker in front of and a little below the torch tip. This allows unobstructed flow of the acetylene. If you hold the striker directly in front of the torch tip, it will fill with acetylene and, when lit, can cause a momentary fireball. When you strike the flint, the torch will light with a slight pop. |  |  |
 Adjust the acetylene knob...  Adjust the acetylene knob until the flame no longer produces black smoke. Now, slowly open the oxygen knob. The flame will change color as more oxygen is added. The next section describes how to adjust the flame, but be aware: If the torch starts to make a humming or buzzing sound at any time, shut off the oxygen immediately. This sound is the result of the flame burning inside the torch tip, a dangerous condition usually caused by gas pressures set too low. |  To shut off the torch, close...  To shut off the torch, close the oxygen knob first, then the acetylene, then close the valves on top of each bottle. Turn the regulator handles counterclockwise to relieve the pressure on the regulators' internal springs. Then purge the remaining gas in the hoses by briefly opening both valves on the torch handle again until the regulators read zero. | |
MAPP stands for methylacetylene propadiene.
| TEMPERATURES OF WELDING PROCESSES |
| TIG welding | 5,000 to 5,500 degrees F |
| Oxyacetylene | 6,300 degrees F |
| Arc welding (stick and MIG) | 6,000 to 10,000 degrees F |
| Plasma cutting | 50,000 degrees F |
| TEMPERATURES OF WELDING GASES |
| GAS | WITH AIR DEGREES F | with oxygen degrees F |
| Acetylene (C2H2) | 4,800 | 6,300 |
| Hydrogen (H2) | 4,000 | 5,400 |
| Propane (C3H8) | 3,800 | 5,300 |
| MAPP gas(C3H4) | 2,680 | 5,300 |
| Natural gas (CH4+H2) | 3,800 | 5,024 |
Natural gas is a mixture of methane (CH4) and other hydrocarbons such as ethane (C2H6), propane, butane (C4H10), and sulfur compounds as odorizers.