Oxyfuel Cutting and Welding
Catalog No. 8609-A
selected STUDENT ACTIVITIES
Fill in the blank: Complete the following statements using the correct word or phrase.
1. ______is colorless, odorless, tasteless, and will support combustion.
2. Full cylinder pressure for oxygen is ______to ______pounds psi.
3. Full cylinder pressure for acetylene is approximately ______pounds psi.
4. The end of the inner cone may produce a neutral flame temperature from about ______to ______degrees F.
5. Besides cutting and welding, the oxyfuel flame is used to ______, ______, ______, ______, and ______.
6. Check for leaks with mild ______and a paintbrush.
7. The regulator adjustment pressure for oxygen and acetylene will vary depending on the ______size and ______thickness.
8. A ______flame has a rounded inner cone, quiet sound, and an equal mixture of oxygen and acetylene.
9. While cutting and welding, the tip of the inner cone should be held ______to ______inch above the metal.
10. Tip size is determined by the drill size of the ______.
11. Acetylene must not be withdrawn from the cylinder at a rate greater than ______psi.
True/False: Circle the “T” if the statement is true or “F” if it is false.
T F 12. Oxyfuel rigs can weld only thin metal.
T F 13. Oxygen cylinders are equipped with double-seated valves and should be opened all the way.
T F 14. Acetylene cylinders not having the wheel type valve opener should be opened less than one turn.
T F 15. Pressure in the acetylene hose line should never exceed 15 pounds psi.
T F 16. Open the regulator valve prior to opening the high-pressure valve on the oxygen cylinder.
T F 17. Goggles need not be worn when working with oxyfuel.
T F 18. Matches may be used for lighting the torch.
T F 19. An oily wipe cloth should be used to clean out the oxygen cylinder fittings.
T F 20. Always bleed hoses and loosen regulator valve screws when work is completed.
T F 21. In fillet welding, overheating may be avoided by frequently dipping the torch into a bucket of water.
T F 22. In brazing, or bronze welding, a flux must be used.
T F 23. In hardsurfacing, a carburizing flame is used.
T F 24. In cutting, a neutral flame is used.
T F 25. Cutting metal should be done over concrete floors.
T F 26. Stand in front of gauges while opening cylinders.
T F 27. It is safe to run two oxyfuel flame-heating tips off the same acetylene cylinder if the tips only consume 10 lbs. psi each of acetylene.
DISCUSSION: Following demonstration by your instructor, briefly discuss and complete the following activities.
28. Assemble the oxyfuel rig.
29. Turn on and adjust the oxyfuel rig.
30. Complete the shutdown of the oxyfuel rig.
SKILL PERFORMANCE ACTIVITIES: Following completion of this topic, practice the following skills as assigned by your instructor.
31. Cutting with Oxyfuel
1. Materials: Mild steel plate (1/4, 3/8, 1/2, 3/4, and 1 inch thick) and 2-inch pipe.
2. Objective: Cut and Pierce Plate; Cut Pipe
3. Procedure:
a. Clean the metal and mark the line to be cut.
b. Properly position the metal so that molten metal and sparks will fall into a container.
c. Select the correct tip and properly align the orifices.
d. Set the pressure and adjust to a neutral flame.
e. The cut can be made free hand or with a guide.
f. Tilt or angle the torch depending on the thickness of the metal.
g. Cut in a straight line.
h. Cut a semicircle.
i. Cut a circle.
j. Pierce a 1/2-inch hole.
k. Cut a 90-degree angle on 2-inch pipe.
l. Cut a saddle on 2-inch pipe.
32. Welding and Brazing with Oxyfuel
Part 1:
1. Material: 14-gauge sheet steel, 4 x 6 inches
2. Objective: Form and Run a Puddle
3. Procedure:
a. Adjust flame to neutral at the desired temperature.
b. Produce a live puddle (1/4 - 3/8 inches in diameter).
c. Hold the tip at a 45-degree angle to the metal pointed in the direction of travel.
d. Using the oscillating motion, move the puddle in a straight line at the proper speed.
e. Examine the result for uniformity.
Part 2:
1. Material: 14-gauge sheet steel, 2 pieces - 4 x 6 inches
2. Objective: Fusion Welding Without a Rod
3. Procedure:
a. Position the two pieces of metal at a right angle and tack weld the ends with a neutral flame.
b. A corner fillet joint will be formed.
c. Establish a live puddle.
d. Using the neutral flame pointed in the direction of travel, begin oscillating the tip.
e. Move at a speed that allows the puddle to properly advance.
f. Examine for flaws and uniformity.
Part 3:
1. Materials: 1/4-inch mild steel plate and mild steel welding rods (copper coated to prevent rusting while in storage)
2. Objective: Fusion Welding With Filler Rod
3. Procedure:
a. Position metal joint and adjust torch flame to neutral.
b. Produce a live puddle.
c. Insert end of rod into the center of the puddle directly under the blue inner cone and proceed to build a bead by oscillating both the rod and the torch, which are held at 45-degree angles to the surface, and move forward at an even speed.
d. Keep the tip of the blue inner-cone at least 1/8 inch above the surface of the live puddle.
e. Examine for uniformity.
Part 4:
1. Materials: 1/4-inch mild steel plate; brazing rods; and general-purpose flux
2. Objective: Braze Welding With Filler Rod
3. Procedure:
a. Clean and position the metal.
b. Set torch to a neutral flame.
c. Heat the end of the rod and dip it into the flux until it is well coated.
d. Bring surface of steel to a cherry red heat (no puddle when brazing).
e. Braze the joint with brass by laying a thin coat of brass along the entire joint.
f. Cut the flame down to 1/2 the original temperature and proceed to build up the bead with no flux on second and/or third pass.
g. Examine for uniformity.
NOTE: Brazing cast iron uses the same technique as mild steel except a special flux must be used.
NOTE: Welding cast iron differs from welding mild steel in that a cast iron rod must be used with a special flux. Allow the weld to cool slowly.
advanced ACTIVITIES
1. Go to the Materials Engineering Group Web site and take the Oxy-Gas cutting test several times over the course of this unit. Report your score to your teacher. Make a chart that documents your score improvement.
2. Obtain some reject horseshoes from a local farrier. Practice your hardsurfacing technique on the toes of the horseshoes.
3. Research the topic Nondestructive Testing. Report your findings to your agricultural science class.
4. Research and develop a presentation focused on the molecules involved in oxyfuel processes. Include chemical formulas and molecular representations of the elements and compounds involved.