A PowerPoint Presentation on Oxyacetylene Welding

1. Oxyacetylene Welding (OAW) The oxyacetylene welding process uses a combination of oxygen and acetylene gas to provide a high temperature flame.

3. The term oxyfuel gas welding outfit refers to all the equipment needed to weld.

4. Cylinders contain oxygen and acetylene gas at extremely high pressure.

5. Typical Oxyacetylene Welding (OAW) Station

7. Oxygen cylinders are forged from solid armor plate steel. No part of the cylinder may be less than 1/4” thick.

8. Cylinders are then tested to over 3,300 PSI using a (NDE) hydrostatic pressure test.

10. Cylinders are regularly chemically cleaned and annealed to relieve “jobsite” stresses created by handling .

12. Never transport with the regulators in place

13. Never allow bottles to stand freely. Always chain them to a secure cart or some other object that cannot be toppled easily.

15. The cylinder valve should always be handled carefully

17. Most regulators have a gauge for cylinder pressure and working pressure.

19. Regulators maintain a constant torch pressure although cylinder pressure may vary

20. Regulator diaphragms are made of stainless steel

22. As pressure in the semicircular end increases it causes the free end of the tube to move outward.

23. This movement is transmitted through to a curved rack which engages a pinion gear on the pointer shaft ultimately showing pressure.

25. Oxygen hoses are green in color and have right hand thread.

26. Acetylene hoses are red in color with left hand thread.

27. Left hand threads can be identified by a grove in the body of the nut and it may have “ACET” stamped on it

29. Flashback arrestors are designed to eliminate the possibility of an explosion at the cylinder.

30. Combination Check/ Flashback Valves can be placed at the torch or regulator.

34. Acetylene is extremely unstable in its pure form at pressure above 15 PSI (Pounds per Square Inch)

35. Acetone is also present within the cylinder to stabilize the acetylene.

36. Acetylene cylinders should always be stored in the upright position to prevent the acetone form escaping thus causing the acetylene to become unstable.

38. Cylinders have safety (Fuse) plugs in the top and bottom designed to melt at 212° F (100 °C)

40. This will allow the cylinder to be closed quickly in case of fire.

41. Cylinder valve wrenches should be left in place on cylinders that do not have a hand wheel.

43. PSI (pounds per square inch) is sometimes shown as PSIG (pounds per square inch -gauge)

45. 1/2” material Oxy 55-85psi Acet 6-12 psi

49. attachment in place of the welding head shown. Welding torches of this general design are by far the most widely used. They will handle any oxyacetylene welding job, can be fitted with multiflame (Rosebud) heads for heating applications, and accommodate cutting attachments that will cut steel 6 in. thick.

50. A full-size oxygen cutting torch which has all valves located in its rear body. Another style of cutting torch, with oxygen valves located at the front end of its handle.

52. Clean torch orifices with a “tip cleaners” (a small wire gauge file set used to clean slag and dirt form the torch tip)

53. Crack (or open) cylinder valves slightly allowing pressure to enter the regulators slowly

54. Opening the cylinder valve quickly will “Slam” the regulator and will cause failure.

56. Check for leaks using by listening for “Hissing” or by using a soapy “Bubble” solution

57. Adjust the regulators to the correct operating pressure

58. Slightly open and close the Oxygen and Acetylene valves at the torch head to purge any atmosphere from the system.

60. Never use a butane lighter to light the flame

62. Carburizing (or “excess acetylene”)

64. Pure Acetylene and Carburizing Flame profiles

65. Neutral and Oxidizing Flame Profiles

67. The excess acetylene flame (Fig. 4-2), as its name implies, is created when the proportion of acetylene in the mixture is higher than that required to produce the neutral flame. Used on steel, it will cause an increase in the carbon content of the weld metal.

68. The oxidizing flame (Fig. 4-3) results from burning a mixture which contains more oxygen than required for a neutral flame. It will oxidize or ”burn” some of the metal being welded.

85. Modern Welding York County School of Technology