OxyFuel Equipment
Introduction
• Oxyfuel welding is a welding process where the
heat for fusion is supplied by an torch using
oxygen and a fuel gas.
• Several different fuel gasses can be used:
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Fuel Gasses





Propane (LPG)
Natural Gas
Acetylene
MAPP
Hydrogen
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Uses
• Traditionally oxyfuel equipment was used for:
–
–
–
–
–
–
–
–
Brazing
Fusion welding
Flame hardening
Metalizing
Soldering
Stress relieving
Cutting
Bending
• New technologies in the GMAW process has almost
eliminated the need for oxyfuel welding.
– Primary uses today are heating, brazing and cutting.
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OxyFuel Safety
• The hazards of oxyfuel welding are primarily compressed gas
cylinders, flammable gases and open flame.
• Common concerns are (pg 294)
– PPE (shade 4 face shield/goggles, gloves).
– Store and handle cylinders correctly.
• Keep caps on cylinders whenever regulators are not attached.
• Never use oil, grease, or any hydrocarbons on fittings.
• Store cylinders in a locked enclosure.
– Check system for leaks
– Follow correct procedures for turning on and off.
– Remove combustible materials from area.
• Cutting slag can travel 35 feet on concrete
– Insure adequate ventilation
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OxyFuel system
• Before discussing how the system works, it is important to know
the name of the parts.
A. Oxygen safety disc
B. Oxygen cylinder valve
C. Oxygen cylinder pressure
gauge
D. Oxygen working pressure
gauge
E. Oxygen regulator
F. Oxygen regulator adjusting
screw
G. Acetylene cylinder safety disc
H. Acetylene cylinder valve
I. Acetylene cylinder pressure
gauge
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OxyFuel System--cont.
J. Acetylene working pressure
gauge
K. Acetylene regulator
L. Acetylene regulator
adjusting screw
M. Acetylene hose
N. Oxygen hose
O. Oxygen torch valve
P. Acetylene torch valve
Q. Torch
R. Welding tip
S. Acetylene cylinder
T. Oxygen cylinder
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Oxygen Cylinder
•
•
•
•
•
•
•
•
•
•
One piece, seamless construction.
Each cylinder has unique serial
number and number is recorded in
national registry.
Scheduled inspection required.
2,200+ psi when filled
Safety disc, nut, releases at 3,000 psi.
Must not be dropped.
Should not be used as a roller.
Never use any lubricates on threads or
any part of the cylinder.
Three common sizes are 244, 150 &
80 cubic feet.
The valve should never be left
exposed. It must always have the
regulator attached or the cap on.
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Oxygen Cylinder Valve
• Special double seat
valve.
• Must be opened all of
the way when in use.
• Right hand threads
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Acetylene Cylinder
•
•
Special cylinder because •
acetylene is unstable above
15 psi.
Acetylene is shock sensitive.
Acetylene cylinders are filled entirely with a
porous materials which must be able to stop
the propagation of an acetylene
decomposition within the cylinder initiated by
a backfire or an external heating of the
acetylene cylinder.
•
250 psi when filled.
•
•
Protected by fuse plugs that melt at 212 oF.
The cylinder should be opened only 1/2 to
3/4 of a turn when in use.
The withdrawal rate in cubic feet per hour
should never exceed 1/7 times the cylinder
capacity.
Common sizes are 300, 120 and 75 cubic
feet.
The cylinders must always be used,
transported and stored upright.
•
•
•
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Acetylene Valve
• Acetylene cylinders
are low pressure
cylinders, therefore the
valve packing can
contain the cylinder
pressure and only a
single seat is used.
• Fuel cylinders are left
hand threads.
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LPG Gas Cylinders
• Simpler hollow steel containers.
• New regulations require float shut-off.
• Because gas is under pressure,
cylinder contains both liquid and
vapor.
• Equipped with spring loaded pressure
relief valve.
• Newer style fitting being adopted.
• Common sizes are 30, 70, and 100
pound.
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Pressure Regulators
• Gas systems must have a
pressure regulator to reduce
the pressure from the high
pressure in the cylinder down to
the working pressure.
• Many different designs are
used.
• They range from simple fixed
output, commonly used for gas
grills and camping stoves,
to double stage regulators used
for oxyfuel welding.
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Regulators
• Oxyfuel welding and cutting
uses two types
– Single stage
– Two stage
• Correct use
– Insure adjusting screw is
back off when shut down.
Check before starting.
– Set correct working
pressure.
• Two potential problems
– Regulator creep
– Gauge not returning to zero
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Regulator Problems
Regulator Creep
• Regulator creep is a potentially dangerous condition that
occurs when the regular does not maintain working pressure.
– When the system is on, and no gas is flowing, the working
pressure slowly increases.
• Potential outcomes:
– Rupture of regulator safety relief valve.
– Explosion of low pressure gauge.
– Rupture of gas hose.
• Causes
– Foreign material inside the regulator.
– Failure to release the regulator adjusting screw before opening
the cylinder.
– Normal wear
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Regulator Problems
Not Returning To Zero
• The bourdon tube inside the
regulator can be damaged,
distorted.
• When this occurs, the gauge
needle does not return to
zero.
• Causes
– Opening cylinder with the
regulator adjusting screw
turned in.
– Hard impact.
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Working Pressure
• Oxygen and fuel gas working pressure should
be set according to manufactures
recommendations for the job being performed.
• Potential problems with excessive pressure.
– Harsh flame
– Damaged equipment
– Increased potential of flashback.
• Potential problems of insufficient pressure.
– Insufficient heat
– Unstable flame
– Increased plugging of welding or cutting tip.
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Size selection c hart f or Vict or we lding t ips.
Welding Tip Size
Metal
Thickness
Tip
Size
Oxy
Pressure
Acet
Pressure
Acet
cf h
1/6 4 "
1/3 2 "
3/6 4 "
1/1 6 "
5/6 4 "
3/3 2 "
1/8"
3/1 6 "
1/4"
3/8"
1/2"
3/4"
1"
1 - 1/4"
2"
3"
4"
000
00
00
0
0
1
2
3
4
5
5
6
7
7
8
10
12
5
5
5
5
5
5
5
7
8
9
10
11
12
12
12
20
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5
5
5
5
5
5
5
7
8
9
10
11
12
12
12
14
15
1
2
2
3
3
5
8
14
21
31
31
41
52
52
65
94
130
Example welding tip selection
and working pressure chart.
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Backfire & Flashback
• Backfire: indicated when the torch goes out with a loud pop.
– Caused by hot metal in the tip.
– The gasses rapidly combust inside the tip and cause a burst of high
pressure.
– When it occurs, stop and inspect the tip and clean if necessary.
• Flashback: occurs when the flame burns inside of the torch.
– Usually accompanied by a shrill hissing or squealing sound.
– May have puffs of black smoke coming out of the tip.
– A potentially serious condition. If not stopped the flame can travel
up the hoses and into the regulator.
– Primary cause is a blocked tip and unequal working pressures.
• The potential harm of both backfires and flashbacks is controlled
through the use of check valves and flashback arrestors.
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Oxyfuel Torch
•
•
The oxyfuel torch is the handle for holding and controlling the system.
It the controls the flow rate of the gasses and delivers them to the
welding tip, or cutting attachment.
•
•
The torch valves should only be hand secured, not tightened.
The valve stem packing should be tightened if gasses leak past or
when the torch valve becomes too easy to turn.
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Oxyfuel Torches
• Safety codes require torches to have check valves and
flashback arresters.
 Note: this is a relative new code. Older torches will not have check
valves or flashback arresters
• If not included, they should be added in line between the
regulator and the torch.
Flashback arrestor
Check valves
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Oxyfuel Welding Tips
• What is normally called a welding tip is actually a welding tip
and a mixing chamber.
• Some manufacturers put the mixing chamber in the torch, Victor
are in the welding tip.
• Tips have different sizes of
orifices.
– Size usually indicated by
number.
– Manufacturers use different
number systems.
– When fuel gas other that
acetylene is used a larger
size tip is required.
• Tips for heating may have multiple
orifices.
• Tips require periodic cleaning.
–A dirty tip will have a forked outer
envelope.
• Tip orifice should be cleaned with a
tip cleaner.
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Using Tip Cleaner
• Start with the smallest size that
will enter the orifice without
excessive force and work up to
orifice size.
• Be careful, a broken tip cleaner
usually means a destroyed tip.
• Clean the face of the tip with the
included file.
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Airacetylene Torch
• Burns a mixture of
acetylene or MAPP and
air.
• As fuel gas flows through
torch it draws in the correct
amount of air.
• Lower temperature than
oxyacetylene.
• Primary use is in soldering
and brazing copper piping.
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Hoses and Connections
• Requires special nonporous hoses.
• Hoses are color coded.
– Green: oxygen
– Red or Black: fuel gas
• Connections
– Oxygen: right hand
– Acetylene: left hand
• Hoses should be protected from hot
metal and physical damage.
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PPE
•
Use protection for:
– Eyes
– Body
•
Eyes
– Correctly shaded lens--not sun glasses.
– Shade 4 or 5
•
Body
– Fire resistant gloves
– Long sleeves
– Button shirt
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Setting Up Oxyfuel System
• Extinguish all open flames and stop processes that produce
sparks.
• Steps (assuming new system)
1. Secure cylinders
2. Remove caps
3. Crack cylinder valves
4. Connect regulators
5. Open cylinder valves
6. Connect hoses to cylinders
7. Connect hoses to torch body
8. Connect welding tip to torch body
9. Set working pressures
10.Check system for leaks.
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Shutting Down System
• Close cylinder valves
• Open torch valves
– Leave open until regulator gauges read zero.
– Some sources recommend doing fuel first and oxygen last.
• Close torch valves
• Release tension on regulator adjusting screw.
• Roll up hoses and place torch in a safe position.
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Questions?
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