Always have suitable fire extinguishing equipment at hand when doing any welding.

When setting up setting up oxyacetylene welding equipment, it is important that all operations be performed systematically in order to avoid mistakes and possible trouble. The setting up procedures given in a through d below will assure safety to the operator and the apparatus.



Do not stand facing cylinder valve outlets of oxygen, acetylene, or other compressed gases when opening them.

  1. Place the oxygen and the acetylene cylinders on a level floor (if they are not mounted on a truck), and tie them firmly to a work bench, post, wall, or other secure anchorage to prevent their being knocked or pulled over.
  2. Remove the valve protecting caps.
  3. “Crack” both cylinder valves by opening first the acetylene and then the oxygen valve slightly for an instant to blow out any dirt or foreign matter that may have accumulated during shipment or storage.
  4. Close the valves and wipe the connection seats with a clean cloth.

Pressure Regulators.

  1. Check the regulator fittings for dirt and obstructions. Also check threads of cylinders and regulators for imperfections.
  2. Connect the acetylene regulator to the acetylene regulator and the oxygen regulator to the oxygen cylinder. Use either a regulator wrench or a close fitting wrench and tighten the connecting nuts sufficiently to prevent leakage.
  3. Check hose for burns, nicks, and bad fittings.
  4.  Connect the red hose to the acetylene regulator and the green hose to the oxygen regulator. Screw the connecting nuts tightly to insure leak proof seating. Note that the acetylene hose connection has left hand threads.
  5.  Release the regulator screws to avoid damage to the regulators and gauges. Open the cylinder valves slowly. Read the high pressure gages to check the cylinder gas pressure. Blow out the oxygen hose by turning the regulator screw in and then release the regulator screw. Flashback suppressors must be attached to the torch whenever possible.


If it is necessary to blow out the acetylene hose, do it in a well ventilated place which is free of sparks, flame, or other sources of ignition.


Connect the red acetylene hose to the torch needle valve which is stamped “AC or flashback suppressor”. Connect the green oxygen hose to the torch needle valve which is stamped “OX or flashback suppressor”. Test all hose connections for leaks at the regulators and torch valves by turning both regulators’ screws in with the torch needle valves closed. Use a soap and water solution to test for leaks at all connections. Tighten or replace connections where leaks are found. Release the regulator screws after testing and drain both hose lines by opening the torch needle valves. Slip the tip nut over the tip, and press the tip into the mixing head. Tighten by hand and adjust the tip to the proper angle. Secure this adjustment by tightening with the tip nut wrench.


Purge both acetylene and oxygen lines (hoses) prior to igniting torch. Failure to do this can cause serious injury to personnel and damage to the equipment.

Adjustment of Working Pressure. Adjust the acetylene working pressure by opening the acetylene needle valve on the torch and turning the regulator screw to the right. Then adjust the acetylene regulator to the required pressure for the tip size to be used (tables 5-1 and 5-2). Close the needle valve. Adjust the oxygen working pressure in the same manner.

Setting up Oxyacetylene Welding Equipment : Tip Sizes