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Chapter 29 Special Welding and Cutting Processes
• Low heat input.
• Controlled welding atmospheres.
• The ability to weld dissimilar metals.
• The ability to weld parts as thin as .001″–.002″
(.025 mm–.050 mm).
• No need for filler metal.
• Very precise aiming of beams to produce
accurate and repeatable welds.
Special Cutting Processes
Special cutting processes using oxyfuel gas and
oxygen arc cutting equipment have been developed
for use in underwater salvaging and repairs. Other
special thermal cutting processes were developed to
permit the cutting of nonferrous metals and even con-
crete. These processes make it possible to cut metals
that cannot be cut using regular oxyfuel gas cutting.
Oxyfuel Gas Cutting (OFC) Underwater
Underwater cutting is often done to repair under-
water structures. It is also used to cut and salvage
sunken ships. Oxyfuel gas cutting (OFC) is a process
that can be done underwater, using a special torch.
The torch is similar to the regular OFC torch, with two
major changes. First, an air jacket is installed around
the cutting tip. Second, a tube is added to carry com-
pressed air to the air jacket, Figure 29-17.
Oxygen and fuel gas are mixed in the torch and
burned at the tip, as in a regular cutting torch. Acutting
oxygen valve and lever directs pure oxygen through
1–Air jacket 14–H. P. valve plug 30–“O” ring (friction)
2–Lock nut 15–Valve spring 31–“O” ring (sealing)
3–Tip nut 16–Seat holder assembly 32–“O” ring retainer
4–Oxygen-hydrogen tip 17–Seat holder 33–Valve stem
Sizes 2 to 7 18–Seat screw 34–Bolt for lever
Oxygen acetylene 19–Seat 35–Lock washer
Sizes 1 to 4 20–Oxygen connection 36–Acetylene control valve assembly
5–Gasket 21–Nut Valve stem assembly
6–Torch head 22–Tailpiece Control valve body
7–H. P. oxygen tube 23–Mixing chamber tube 37–Nut
8–H. P. oxygen tube coupling nut 24–Mixing chamber nut 38–Tailpiece
9–Ferrule 25–Spiral mixer 39–Compressed air tube
10–Lock nut 26–Acetylene tube 40–Compressed air tube coupling nut
11–Barrel 27–Inner oxygen tube 41–Oxygen valve stem assembly
12–Rear H. P. oxygen tube 28–Lever 42–Compressed air valve assembly
13–Body 29–H. P. valve “O” ring retainer assembly Valve body
Valve stem assembly
39
40
42
22
21
20
38
37
36
35
34
33
32
31
29
30
13
14
15 16 17
41
OXY
18
19
28
7
8
9
10 11
12
27
26
25
24
23
6
5
4
3
2
1
Figure 29-17. A cross-sectional drawing of an underwater oxyfuel gas cutting torch. The air valve, part #42, controls the air-
flow to the air jacket, part #1. The air flow is shown in cross-hatched light green with red arrows. This high-pressure air keeps
water away from the cutting tip. (Victor Equipment Co.)