1. Oxyacetylene Cutting

2.  After completing this chapter, you will be able to: ◦ Demonstrate the proper and safe method of setting up cylinders, regulators, hoses, and the cutting torch ◦ Demonstrate how to maintain a cutting tip and torch ◦ Demonstrate how to light a torch, adjust it, and make a cut ◦ Describe a good oxyacetylene cut ◦ Discuss safety procedures to be followed when oxyfuel cutting Chapter #21 – Oxyacetylene Cutting

3.  Primary cutting process in oxyfuel gas cutting (OFC) ◦ Uses heat from oxygen fuel gas flame  Raises metal temperature to kindling temperature  High-pressure stream of oxygen is directed onto the metal, causing it to be cut (rapidly oxidized) ◦ Processes are identified by fuel type mixed with oxygen to produce the preheat flame Chapter #21 – Oxyacetylene Cutting

4. Table 21-1 Fuel Gases Used for Flame Cutting FIGURE 21-1 (A) Oxyacetylene portable cutting rig mounted on a handcart for use in a shop area. (B) Oxyacetylene setup mounted on a trailer for use outside of a shop. Larry Jeffus A B Chapter #21 – Oxyacetylene Cutting

5.  Oxyfuel gas cutting ◦ Used to cut iron base alloys (ferrous metals) ◦ Low carbon steels (up to 0.3% carbon)  Easy to cut ◦ High nickel steels, cast iron, and stainless steel  Considered uncuttable with OFC-A ◦ Nonferrous metals (e.g., brass, copper, and aluminum)  Cannot be cut by oxyacetylene cutting Chapter #21 – Oxyacetylene Cutting

9.  1) GOGGLES (shade 4-6)  2) GLOVES  3) PROTECTIVE CLOTHING Chapter #21 – Oxyacetylene Cutting

10.  1) Working area must be clear of unnecessary items  2) Protect yourself and others from flying sparks  3) Support and balance the metal being cut  4) Clear space underneath the cut  5) Use proper technique in starting a cut Chapter #21 – Oxyacetylene Cutting

11.  Oxyacetylene hand torch ◦ Most common oxyfuel gas cutting torch  Most cutting tips are made of copper alloy, but some tips are chrome FIGURE 21-2 Oxyfuel cutting torch. Thermadyne Industries, Inc Chapter #21 – Oxyacetylene Cutting

12. FIGURE 21-4 A mixing chamber located in the tip. American Welding Society FIGURE 21-5 Injector mixing torch. American Welding Society Chapter #21 – Oxyacetylene Cutting

13. FIGURE 21-7 Different manufacturers have differently designed cutting torch tip seats. Larry Jeffus Chapter #21 – Oxyacetylene Cutting

14.  THE CUTTING TIP Other Gases Acetylene Preheat Flame Holes Cutting Oxygen Hole Chapter #21 – Oxyacetylene Cutting

15.  Exactly like setting up oxyfuel welding equipment ◦ Except for adjustment of gas pressures  Refer to Chapter #21 of the text  Greater detail and practice will take place in shop Chapter #21 – Oxyacetylene Cutting

16.  Proper alignment of preheat holes will speed up and improve the cut FIGURE 21-19 Tip alignment for a square cut. American Welding Society FIGURE 21-20 Tip alignment for a bevel cut. American Welding Society Chapter #21 – Oxyacetylene Cutting

17.  Laying out a line ◦ Done with soapstone or a chalk line ◦ Scribe or a punch can be used FIGURE 21-22 Holding the punch slightly above the surface allows the punch to be struck rapidly and moved along a line to mark it for cutting. Larry Jeffus Chapter #21 – Oxyacetylene Cutting

18.  Tips size selection: ◦ Designated by manufacturer numbering system ◦ Refer to manufacturer’s recommendation chart ◦ Size needed is determine by “material thickness” ◦ Pressure are then selected from chart Chapter #21 – Oxyacetylene Cutting

19. Table 21-6 Cutting Pressure and Tip Size Chapter #21 – Oxyacetylene Cutting

20.  Oxyfuel gas cutting torch ◦ Metal cut rapidly oxidizes or burns  High-pressure stream of oxygen is directed on metal preheated above kindling point ◦ Burning away of metal is a chemical reaction with iron (Fe) and oxygen (O)  Oxygen forms an iron oxide  Heat is produced by metal as it burns Chapter #21 – Oxyacetylene Cutting

21.  THE WELDING TORCH OXYGEN VALVE MUST BE WIDE OPEN Chapter #21 – Oxyacetylene Cutting

22.  THE HIGHER OXYGEN PRESSURE WILL CAUSE THE OXYGEN TO BACK UP THE ACETYLENE HOSE, CAUSING A HIGHLY EXPLOSIVE GAS TO COLLECT IN THE ACETYLENE HOSE Chapter #21 – Oxyacetylene Cutting

23.  PRESS THE CUTTING OXYGEN VALVE Chapter #21 – Oxyacetylene Cutting

25.  THE SPACE LEFT WHEN THE METAL IS CUT Chapter #21 – Oxyacetylene Cutting

26.  THE THICKNESS OR DISTANCE OF THE BEVEL 1.4 “ 1” Chapter #21 – Oxyacetylene Cutting

27.  MAKE A SMALL GOUGE WITH A COLD CHISEL, HACK SAW OR ZIP CUT Chapter #21 – Oxyacetylene Cutting

28.  Oxyacetylene torch ◦ Indispensable tool  Speedy  Accurate  Saves time FIGURE 21-92 Nuts and bolts on this rusty plow could not be taken off without a torch. Larry Jeffus Chapter #21 – Oxyacetylene Cutting

29.  Next set of slides deal with flame cutting technique  Review if time permits Chapter #21 – Oxyacetylene Cutting

30.  Allow better control and even cutting FIGURE 21-38 Using angle irons to aid in making cuts. © Cengage Learning 2012 Chapter #21 – Oxyacetylene Cutting

31.  Easier if one side of the metal is scrap ◦ Cut is turned out a short distance into the scrap side  No side is scrap ◦ Forward movement should be stopped before releasing cutting lever FIGURE 21-40 Turning out into the scrap to make stopping and starting points smoother. © Cengage Learning 2012 Chapter #21 – Oxyacetylene Cutting

32.  Burning a hole in the plate FIGURE 21-59 Sequence for piercing a plate. © Cengage Learning 2012 Chapter #21 – Oxyacetylene Cutting

33. FIGURE 21-83 Small diameter pipe can be cut without changing the angle of the torch. After the top is cut, roll the pipe to cut the bottom. © Cengage Learning 2012 FIGURE 21-84 On large diameter pipe, the torch is turned to keep it at a right angle to the pipe. The pipe should be cut as far as possible before stopping and turning it. © Cengage Learning 2012 Chapter #21 – Oxyacetylene Cutting

34.  THE CUT WILL BE CLEAN AND FREE OF SLAG Chapter #21 – Oxyacetylene Cutting

35.  THE KERF WILL HAVE A ROUNDED TOP EDGE AND SLAG WILL ADHERE TO THE BOTTOM OF THE CUT Chapter #21 – Oxyacetylene Cutting

37.  NOT ENOUGH PREHEAT WAS USED Chapter #21 – Oxyacetylene Cutting