Oxygen Acetylene Welding

OXY-ACET EQUIPMENT

I. CYLINDERS

Cylinders are controlled by the Interstate Commerce Commission.

If you buy one from a second party, get a receipt. Stolen tanks can result in jail time and fines.

ICC # is located on the top ring.

A. OXYGEN Cylinder – Usually Green

Right hand threads.

High pressure. 2200 p.p.s.i

Never oil or grease any part of the oxygen system.

Always turn valves on all the way to prevent gas leakage.

B. ACETYLENE Cylinder – Usually yellow or red

Low pressure. Tanks filled with a

silicon mold to cushion the volatile gas.

Never exceed 15 p.p.s.i

Left hand threads. Open Acet. Valve ¼ to

1 full turn at most. Fusible plug at the

bottom that will melt out if there is a fire. Lead alloy plug.

Ruler quiz. Fill in the fraction. 16th scale.

12

3

4

56

7

8

910 11

12

1314

15

Either draw a ruler and label the lines or number your paper from 1-15 and write in the correct answers.

II. FIVE STEPS TO LIGHTING THE OXY-ACET TORCH

A. Visual check of equipment.

Check hoses for cuts, burns or loose fittings.

Check torch – Valves turned off, proper tip & tip in good repair.

B. Check regulators

Adjusting valves must be out/off/free

Gages should read “0” – if not bleed lines and relieve valves.

C. Turn on sources – SLOWLY

Open acetylene valve ¼ to 1 full turn at most.

Open oxygen valve slowly.

– Stand to one side of unit.

– Open valve all the way SLOWLY

D. Dial in regulators (Adjusting screws)

Oxygen – For welding set at

3-7 p.p.s.i– For cutting set at

18-30 p.p.s.i Acetylene

– Set at 3-7 p.p.s.i for both functions.

Properly adjusted regulators.

E. Light the torch (goggles on) Adjust the flame. Open the

acetylene torch valve ¼ turn.

Light the torch with a striker – point torch under vent and adjust to no smoke. (Do not gap flame)

Open Oxygen valve slowly and adjust to desired flame.

III. FIVE STEPS TO TURNING THE OXY-ACET TORCH OFF

A. Torch handle

Turn off the oxygen torch body valve.

Turn off the acetylene torch body valve.

B. Turn off sources – cylinders

C. Bleed both systems

Open acet. torch valve – gages should go to “0”, close torch valve

Open oxygen torch valve – gages should go to “0”, close torch valve.

D. Relieve the regulators.

Turn adjusting screws out/off/free

E. Clean up.

Mark or cool hot metal.

Inspect and put equipment away.

Put stool up, pliers back, goggles away, then clean work area & floor.

After the torch is lit, you must adjust the oxygen and acetylene to the proper flame for the job.

IV. THE THREE OXY-ACET FLAMES

A. CARBONIZING FLAME –

Too much acetylene, not enough oxygen. Also called a reducing flame. 5500°

B. NEUTRAL FLAME –

Equal amounts of oxygen and acetylene. 6000°

C. OXIDIZING FLAME –

More oxygen than acetylene. 6300° The metal will bubble and boil.

Ruler quiz. Fill in the fraction. 16th scale.

12

3

4

56

7

8

910 11

12

1314

15

Either draw a ruler and label the lines or number your paper from 1-15 and write in the correct answers.

DEFINITION OF TERMSWelding – Joining of 2 like metals with or without 3rd like metal through fusion. (Cohesion)

Definitions Cont.

Brazing and Soldering:– These methods are used when

joining two different materials that can’t melt together.

– Brazing happens over 800° Soldering is under 800°

WELDING PROCEDURES

Once you obtain the proper flame, hold the torch so the tip is perpendicular to the work on both planes.

Forehand – Angle the torch into weld & push the puddle.

Easiest to learn Thin metals Preheats metal

Torch motion

Puddles – Running a liquid puddle of base metal across the plate. The puddle should penetrate the metal. Cone should be 1/8” above base plate.

Bead – Running a puddle and adding a filler rod to the center of the puddle. Use a dabbing motion with the filler rod. Hold it in the flame – keep the end of the rod red hot.

Tack – A small weld holding 2 pieces together for positioning and securing to recheck layout and weld. Align pieces – gap (space depends on metal thickness). Heat both pieces, add filler and fuse both

plates together.

Filler Rod –

Classified by the A.W.S. (American Welding Society)– 36” lengths – 1/16”, 3/32”, 1/8” dia.

Most common

OXY-ACET WELDING PROBLEMS

Torch will pop – whistle – go out – or all three, which, means you have experienced a Flashback or Backfire.

Causes are: Tip is dirty “O” rings are bad Tip too small (flame too large) Cone too close to metal Tip is loose Tip too big (flame too small)

Flashback / Backfire – With a Flashback, black smoke will come out of the tip and the handle will get hot. A backfire is a burning of the gasses in the TIP only. If you have a Flashback, do the following in this sequence:

Turn off torch valves Turn off sources Notify Instructor Check equipment

Too cold – (flame too small) – Bead will sit on top of plate, shallow penetration, not fused together.

Too hot – (flame too big) – Bead sags, too much penetration. Hole burned in metal.

OXY-ACET WELDING SAFETY

Goggles

Protect you from glare and splatter.

Filter plate - #5 shade lens

NEVER…

Exceed 15ppsi on acetylene line pressure regulator.

Use oil or grease on any welding apparatus. Light the torch with both valves open. Light the torch with a match or lighter. Open acetylene tank valve more than 1 full

turn. Relight torch from hot metal or another torch. Watch or work without goggles. Wear nylon clothing when using torch. Weld on anything that has had gas, oil or

solvent in it.