FLAME
CUTTING
HANDBOOK
2
BUG-O SYSTEMS
BUG-O Systems’ Kits are assembled from modular
components. Each kit was originally an adaptation to
meet an actual problem. The concept is both practical
and economical, and is quickly and easily adapted
on the job site.
Initially developed to carry cutting torches in a precise
work path, the primary aim of the BUG-O System is
movement at controlled speed and direction in any
position. The secondary function is to provide suitable
holding or clamping devices to make BUG-O integral
with both the workpiece and the cutting or welding
tool.
BUG-O is more than a flame cutting system- it’s a
revolution in welding procedures. Ingenious customers
have developed hundreds of ways to cut time and
costs by putting this system to work for them, and
most of the these applications have saved the cost of
the unit on the first job.
With BUG-O Systems you can double your welding
production!
The nucleus of the BUG-O System of modular path
and rate control components is the BUG-O. It is a
self-propelled multipurpose carriage and rail system
with infinitely variable speeds. A steel pinion meshes
with a machine-cut steel rack to provide a positive
drive. The BUG-O is locked onto a rail, which is
mounted on the work.
The BUG-O unit is suitable for use with the most
advanced electric welding processes. It is also the
practical way to carry any process requiring precision
movement; in applications such as gouging, spraying,
guiding ultrasonic inspection and others.
3
PRECISION HOLE BORING,
BEVELING AND WELDING
HOB-O cuts, bevels or welds in any position….. any
plane or angle. Carry the tool to the work. HOB-O
weighs only 30 lbs. (18.6 kg)… can be moved and
placed in minutes by one man. Powerful magnets
lock it to the workpiece …. exactly where you want it.
Easily adjustable, the HOB-O flame bores holes from
1'' to 8'' (25-200mm) diameter, inside the machine
and 14-1/2'' to 48'' (368-1220mm) diameter, out side.
Self-propelled, it has an infinitely variable speed control
to suit any application. HOB-O gives you the precision
of drilling … the speed of flame boring … and the
convenience of a portable tool costing less than one
4'' high speed drill bit.
4
A DIVISION OF WELD TOOLING CORPORATION
3001 WEST CARSON STREET PITTSBURGH, PA USA 15204
PHONE: 1-800-245-3186 www.bugo.com FAX: 1-412-331-0383
PREFACE
This booklet has been prepared to show how to
operate and maintain “Gas Cutting” equipment.
Specifically, it shows how to set up, light, set travel
speed and position the “Cutting Torch” for a quality
cut.
WELD TOOLING CORPORATION. 2008
280 TECHNOLOGY DRIVE
CANONSBURG, PA 15317 U.S.A.
PHONE: (412) 331-1776
FAX: (412) 331-0383
For Additional Information Please
Go to Our Website: www.bugo.com
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6
INTRODUCTION
GAS CUTTING OF FERROUS
(CARBON STEEL) METALS
Gas cutting is a process of preheating carbon steel to
its combustion temperature, then burning it rapidly by
means of a regulated jet of oxygen. A cutting torch is
used for this operation.
The process is primarily a chemical one. It is based
on the chemical relationship of oxygen to iron metals
that have been heated to a temperature of 1400° to
1600° F (760° to 871° C). Only the metal within the
direct path of the oxygen jet is affected.
In cutting, a “kerf” is formed. This is a narrow slit having
uniformly smooth and parallel walls. A skilled workman
using a BUG-O and a machine cutting torch can
maintain the following tolerances with respect to
squareness and straight alignment of the cut surface:
1/32nd of an inch (.79mm) on plate thickness up to 4
inches (100mm) and 1/16th of an inch (1.58mm) on
plate thicknesses from 4 to 12 inches (100 to 300 mm).
In actual gas cutting, the iron or steel removed from
the “kerf” is not entirely burned or consumed by the
oxygen. About 30 to 40 percent of the met al is washed
out of the cut as unconsumed or metallic iron due to
the eroding effect of the oxygen jet.
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CONTENTS
BUG-O Systems ................................................. 3
HOB-O................................................................ 4
Preface ............................................................... 5
Introduction ......................................................... 7
Safety Instructions........................................ 10-1 1
Instructions and Precautions for Gas Cutting
A. Safety ........................................................... 12
B. Burning Equipment ....................................... 12
1. Torches ................................................. 12
2. Hoses ................................................... 13
3. Regulators ............................................ 14
4. Tips....................................................... 15
5. BUG-O Machine.................................... 16
C. St art-Up Procedure....................................... 17
1. Hooking-Up........................................... 17
2. Burning Tips.......................................... 18
3. BUG-O Machine.................................... 18
4. Lighting the Torch and Setting
the Preheat Flame................................. 19
5. Adjusting the Preheat Flame
for Making a Square Edge Cut ............. 19
6. Starting Cut ........................................... 20
7. Observing the Cut ................................. 21
D. Procedure for Making a St arting Hole........... 24
E. Observing a Cut Being Made ........................ 24
F. Bevel Cutting................................................. 29
Cutting Notes .................................................... 33
Machine Cutting Tip Chart................................. 34
LIT-FCH-IPM-0608
9
SAFETY INSTRUCTIONS
EVERY TIME a machine cutting torch is used the
following safety and operation precautions MUST BE
PRACTICED! Deviation from the following safety and
operation instructions can result in fire, explosion,
damage to the apparatus or injury to the operator.
1. Inspect the inlet connections, valves, and torch
head for dirt, dust, oil, grease, or damaged parts.
Dirt or dust can be removed with a clean cloth.
DO NOT USE THE CUTTING TORCH IF OIL
OR GREASE IS PRESENT! Have your
manufacturer’s repair center clean the torch or
repair any damage.
2. Inspect the torch head. The tapered seating
surface must be in good condition. If dents, burrs
or burned seats are present, the seat must be
resurfaced. If the torch is used with poor setting
surface, backfire or backflash may occur and
damage the equipment.
3. Select the required size and type of cutting tip.
Inspect the tip seating surface for damage.
REMEMBER- these seating surfaces prevent
premature mixing of gases that can cause fire
and explosions. If the tapered seats on the tip
are damaged, DON’T USE IT! Inspect the preheat
and cutting oxygen holes. Sp atter can stick on or
in these holes but can be removed with a tip
cleaner.
4. Insert the tip in the Cutting T orch head and tighten
securely .
5. Adjust the regulator delivery pressures according
to the size and type of tip being used.
6. IMPORT ANT: Always purge out the cutting oxygen
passages by opening the cutting oxygen valve
(at least five seconds before lighting the torch.)
Open the fuel valve approximately one-half turn
and ignite the gas with a spark lighter. Adjust the
fuel valve until the flame clears the end of the tip
about ½ inch (13mm), then reduce slightly to
return the flame to the tip.
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7. Slowly open the preheat oxygen valve until a
neutral flame is established (a sharp inner cone).
SPECIAL NOTE FOR TWO HOSE MACHINE
TORCHES ONLY: After the neutral flame has
been established as described, open the cutting
oxygen valve. Note that the preheat flames
change slightly from neutral to a carburizing flame
with a feather. With the cutting oxygen flowing,
adjust the preheat oxygen valve until the preheat
flames are again neutral.
8. If you experience a backfire or backflash (a hissing
sound when the flame is burning inside the cutting
torch) IMMEDIATELY turn off the preheat oxygen
valve, then shut off the torch fuel valve. Allow the
cutting torch to cool before attempting to re-use it. If
trouble persists, call your manufacturer’s repair center.
9. WHEN YOU FINISH YOUR CUTTING
OPERA TION:
a. First shut off the oxygen preheat valve, then
shut off the torch fuel valve. If this procedure
is reversed, a “pop” may occur. The “pop”
throws carbon soot back into the torch and
may in time partially plug it.
b. Close both cylinder valves.
c. Open the torch oxygen preheat valve, and
release the pressure in the hose and regulator.
Close the torch valve.
d. Turn the adjusting screw on the oxygen
regulator counter-clockwise until the adjusting
spring pressure is released.
e. Open the torch fuel valve and release the
pressure in the hose.
f. Repeat “d” using fuel regulator.
g. Close all valves on torch handle and the
cutting attachment.
NOTE: The use of Reverse Flow Check Valves is
strongly recommended to reduce the possibility of
mixing gases in the hoses and regulator. Mixed gases
will rapidly burn once the torch is lighted. These
combustible gases can explode in the hoses, regulators
or cylinders, resulting in serious injury to the operator.
11
INSTRUCTIONS AND PRECAUTIONS
FOR GAS CUTTING
A. SAFETY
1. Before handling or using any flame cutting
equipment, understand and apply at all times
the safe-practice instructions in this manual.
a. Be sure work areas are free of flammable
and combustible or explosive materials.
b. Always wear protective personal
equipment.
(1) A close-fitting hat with hair tucked in.
(2) Flame retardant clothing. Shirt- collar
buttoned close around neck; pockets
with flaps buttoned; full length
sleeves, fastened at the wrist.
T rousers- must cover top of shoes-
no cuffs!
(3) Hightop work shoes.
(4) Approved eye protection.
(5) Leather work gloves.
B. BURNING EQUIPMENT
1. T orches
a. A 2- or 3-hose machine torch 8 to 15
inches (203 to 381 mm) long is generally
used on BUG-O machines.
b. 3-hose torches are recommended for
heavy cutting on steel thicknesses up to
36 inches (914mm).
c. Torch valves, bodies and racks should
be in good condition and have no gas
leaks.
(If a torch is damaged in any way, it
should be sent to the supplier for repair.)
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2. HOSES
a. Use ¼ inch (6.4mm) twin and single
hose (red for gas and green for
oxygen) with “B” size fittings. The
(notched) fitting is for gas and the
smooth fitting is for oxygen.
b. Fitting should be clamped tightly so
there will be no gas or oxygen
leakage. However, avoid stripping the
threads of the clamps and fittings.
c. Hoses with kinks, burned spots or
small cuts are very dangerous, and
will affect the quality of the cut.
d. If hose is damaged, should be spliced
or scrapped. NEVER USE T APE TO
STOP A LEAK. It is dangerous, and
could cause a fire or explosion which
could seriously injure the operator or
others.
e. For a three-hose torch, the oxygen
hose has a 3/8 (10mm) to ½'' (13mm)
inside diameter to allow a greater
volume of oxygen flow for cutting.
f. The 50-foot (15.2m) standard length
of hose should be used. Additional
lengths of 25 feet (7.6m) can be
added. It is important for the operator
to know the exact total length of hose
connected to the torch so the regulator
gage can be set with the correct
pressure. Increase oxygen pressure
5 pounds (3515 Kg/M²) and gas
pressure 1 pound (703 Kg/M²) for
each additional 25 feet (7.6m) of hose.
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3. REGULATORS
a. Regulators are reducing valves used to reduce
the high supply pressure to that which is desired.
The gage on the regulator indicates the
pressure at which gas is supplied to the torch.
b. The Regulators should be handled with care.
Damaged regulators will give inaccurate
pressure readings which will affect the quality
of the cut. The needle should read 0 before
pressure is applied.
c. Grease or oil should never be used on
regulator fittings because they can cause
burning or explosion of lines.
d. Gas and oxygen outlets should be blown out
to remove grit or dust, before attaching to the
regulator.
e. If needle on gage appears to be stuck when
pressure is applied, tap lightly with your finger .
If this does not cause the needle to move, the
gage should be sent to the repair department.
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4. TIPS
a. The proper care of a tip will allow many feet
of burning before it wears out.
b. Tip cleaners should be used periodically to
insure that holes are not plugged and that
there are no burrs to deflect the gas.
c. The seat of the tip should be smooth to make
a tight seal. If the seat is damaged, it will have
a nick or nicks. This allows gas to escape and
produces a flame around the top of the tip.
d. Tips should never be thrown in a tool box.
They should be kept in their boxes or placed
in special holding racks.
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5. BUG-O SYSTEM (PORT ABLE)
a. The BUG-O should be in good condition
so it will travel smoothly and at a steady speed.
(1) Check the wheels to make sure there are no
burrs or spatter stuck to them. They should
be smooth and clean and rotate freely.
(2) The speed adjustment knob should turn
smoothly to allow speed-up or slow-down from
one setting to the other.
(3) The track ways or “grooves” should be
periodically brushed clean. This removes
particles that could obstruct the wheels and
ruin the cut. The track should be straight with
no burrs or nicks in the grooves.
(4) If the BUG-O or track is damaged or does not
work well, have it repaired.
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(5) The gears in the machine may eventually
become worn, permitting excessive backlash.
With the machine on the track, and the clutch
engaged the BUG-O should not move more
than 1/8 inch (3mm) back and forth when hand
pressure is applied in these directions.
C. ST ART UP PROCEDURE
1. HOOKING UP
a. Secure cylinders in upright position. Blow out
gas and oxygen supply station outlets to
remove any dust and grit particles.
b. Attach regulators to outlet. Finger tighten
connections. Use a wrench to make snug.
Be careful not to strip the threads.
c. Attach hoses to regulators. Finger tighten
connections. Use a wrench to make snug. Be
careful not to strip the threads.
d. Place BUG-O in approximate position to make
cut.
e. Insert torch into holder on the BUG-O.
f. Attach hoses to the torch. Finger tighten
connections. Use a wrench to make snug.
Be careful not to strip the threads.
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g. (1) V alves on torch should be closed.
(2) Turn valve on regulators counterclockwise
until it moves freely so no pressure will
register.
(3) Open acetylene cylinder valve ½ turn.
Open oxygen cylinder valve all the way .
(4) Slowly open gas and oxygen valves on
torch and turn wide open.
(5) Slowly turn in regulator valve until desired
pressure is reached on gas and oxygen.
(See torch manufacturer’s tables for
recommended oxygen and gas
pressures.)
(6) Close valves on torch.
2. BURNING TIPS
a. Select tip (see torch manufacturer’s table
for recommended tip sizes).
b. Inspect tip.
c. Use tip cleaners to insure holes are clean
and square on used tips.
3. BUG-O
a. Brush off dust/dirt form track grooves,
work surfaces and magnet plates.
b. Place rail on work parallel to cut-line.
Position torch over cut-line.
c. Adjust speed to approximate burning
speed.
(1) Set indicator on 20, 30 or 40 on dial.
(2) Place torch tip ¼ inch (6.4mm) above
plate and mark with soap stone. This is
the starting point.
(3) Using the second hand on a watch, start
the travel machine when the second hand
is on 12.. Let the machine travel for one
minute, then stop by throwing the switch.
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(4) Using a soap stone, mark the spot where
the tip stopped. Measure the distance
between the two marks-“This is inches
(mm) per minute travel.”
(5) Repeat a different dial positions to
establish correct speed settings.
(6) See tables for recommended travel
speed settings.
4. LIGHTING THE TORCH AND SETTING THE
PREHEA T FLAME
a. Adjust cutting goggles over eyes.
b. Put on gloves.
c. Open gas valve ¼ turn.
d. Open preheat oxygen valve 1/8 turn.
e. Put striker at tip end and light torch.
f. Adjust preheat flame to neutral by turning
oxygen and gas valves one at a time and
watching the blue flame cones for
sharpness.
5. ADJUSTING THE PREHEAT FLAME FOR
MAKING A SQUARE EDGE CUT
a. A simple rule to follow when a square edge is
desired is to have the preheat flame come
out as a whisper or a shoooosh rather than
having a rush of gas and oxygen come out
with such a force that the preheat flame has
a shrill whistling sound. The whispering
preheat flame has just enough heat to keep
the leading edge and sides of the cut barely
melting. Little sparkles will be present around
the top surface of the hole which indicates
that a correct preheat flame is used to give a
square edge to the top of the cut. The
whistling preheat flame has too much heat
that keeps the leading edge and sides melting
and will cause a rolled edge to the top of the
cut.
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b. Place tip half over the edge of plate.
c. Plate edge should start to get red.
1) If the plate edge does not start to melt
(making fluid puddle), preheat flame is
too cold.
2) If edge starts to melt too much (a fluid
puddle the same diameter as the tip end),
the preheat flame is too hot.
c) To adjust the too hot preheat
flame (so that just enough
heat is put into the plate to
have a square edge on top of
cut):
(1) Both the oxygen and gas
valves must be slowly closed
to reduce the preheat flame.
First, close the oxygen valve
slightly until the blue flame
gets longer. Then close the
gas valve until the blue flame
shortens to the correct original
length.
(2) Watch plate edge until fluid
puddle is approximately ½ the
size of the torch tip.
d. It is better to start with a cold preheat flame and
slowly increase the oxygen and gas flow until a
small molten fluid puddle appears on the starting
edge of the plate.
6. START CUTTING (See para. C for detailed
procedure for making a starting hole.)
20
a. With acetylene, natural of propane gas the
tip end should be placed about 1 to 3 times
the length of the blue flame cones away from
the plate surface (about 1/8 or 3/8'' [3 or 10
mm] high). For MAPP gas the tip should be
maintained from ¼ to 3/4'' (6 to 19mm) from
the plate.
b. The torch should be square with the plate.
Do not tilt torch.
c. The top of the plate should be preheated for
a distance of 1-1/2'' to 2'' (38 to 50mm) by
moving the torch slowly back and forth over
the area.
d. Bring torch to edge of plate so ½ of the preheat
flame is touching the plate.
e. Hold at this position until a molten puddle starts
to form (a little extra preheat oxygen
sometimes is necessary to start this action
and should be reduced after the cut is started).
f. Open cutting oxygen valve and start to cut.
g. Throw the travel machine switch to start travel
along plate and immediately open the cutting
oxygen valve to start cut.
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h. If travel is not started immediately , the bottom
1/3 of the cut will pocket and gouge due to
the expanding oxygen gas and the molten
slag, the same as too slow a travel speed
would make. The top of the cut should always
lead the bottom of the cut even if it’s only 1/16
(1.6mm) on an inch. This prevents the
opening or kerf from being clogged with slag.
It is better that the cut be made a little on the
fast side, which would give a rippled wave
appearance, rather than on the slow side
which would require repairing or reburning.
7. OBSERVING THE CUT
a. Minor adjustments may have to be made to
insure good smooth cut.
(1) The “high quality” cut is shown in Sketch #1.
Top edge is square, face smooth, side scale
pulls away from the sides, bottom slag comes
off clean with a little tap, torch tip height and
travel speed is correct.
22
(2) In sketch #2 the top edge has a roll. Too hot
a preheat flame has melted away the edge
and rounded the corners. To avoid this, the
preheat flame must be reduced by slightly
closing the preheat oxygen valve and the gas
valve. Keep repeating this procedure until
edge cut is square.
23
(3) Gouges or pockets have formed at the bottom
½ or 1/3 of cut shown in Sketch #3. This was
caused by using too high a pressure on the
cutting oxygen or too slow travel. Pressure
should be reduced or travel speed increased.
Excess oxygen will expand and gouge the hot
area of burn towards the bottom of the cut.
D. PROCEDURES FOR MAKING A STARTING
HOLE WITH A MACHINE BURNING TORCH
a. A 2- or 3- hose torch can be used with a 3/8''
(10mm) dia. oxygen hose, for volume, with a
regulator setting of 80 to 85 PSI (KG/M²).
b. The pre heat flame should be set a little hotter
than for the normal cut to get the surface
heated and melting faster.
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c. The tip of the torch should be no less than 5/
8'' (16mm) from the surface.
d. As soon as the surface area starts to form a
molten puddle from the preheat flame, the
cutting oxygen valve is opened and the torch
raised to 1-1/2 to 2'' (38 to 50mm) above the
surface to prevent the molten metal from
clogging the cutting nozzle or tip.
e. CAUTION: The torch holder should be firm
without play, so that the torch will not vibrate
during the raising motion.
f. As soon as the material is pierced, lower torch
to cutting position (3/8'' to ½'' 10mm-13mm)
and start carriage travel.
E. OBSERVE THE CUT BEING MADE
In this series for sketches, a correct cut as
well as undesirable cuts and their causes are
illustrated.
1. This sketch shows the result of using correct
cutting techniques. The face of the cut is flat
and regular, and the draglines are smooth,
uniform and practically vertical. This is an
excellent surface which can be welded without
machining.
25
2. The travel speed was a little too fast in this cut.
This is shown by the angle (or rake) of the
dragline. The surface of such a cut is rippled
but reasonably smooth. It required a minimum
of grinding to be welded without machining.
3. In this cut, the travel speed was a little too slow.
This caused an accumulation and sticking of
molten slag which resulted in the irregular
surface. Gouging and pockets such as these
will have to be built back by welding. They must
then be machined or hand ground before the
cut surface can be used as a proper weld joint.
26
4. The torch was too far from the work in this cut.
It produced excessive melting at the top edge
of the cut. A thin layer of scale will stick
approximately 1/3 to 1/2 the depth of the cut.
Slag will also stick to the bottom edge of the cut.
The scale and slag must be vibrated or chipped
to make the surface suitable for welding.
5. Here the torch top was too close to the work.
It caused a portion of the inner cone of the
preheat flame to burn inside the top portion
of the cut. This produced an unstable cutting
action and resulted in the rough (small pockets
or gouges) edges at the top quarter of the
cut. Areas such as these must be machined
or ground to make them suitable for welding.
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6. Too much pressure on the cutting oxygen
produces a cut of this type. The combustion
and melting of the steel always follows the
pattern of the oxygen jet. Excessive or high
oxygen pressure causes undue expansion of
the gas as it leaves the torch tip. This results
in excessive turbulence which gives the
distorted and unsightly cut shown. Scale is
thick and sticks to the surface. Top portion of
cut is undercut. Slag is stuck to the bottom of
the cut. A cut such as this also must be
machined or ground to make it suitable for
welding.
28
7. High preheat flame was used in this cut. The
top surface is melted and rolls over the edge
as small globs of metal. This cut must be
machined of ground to make it suitable for
welding.
8. A dirty or slag-clogged tip was used in this
cut. It caused the oxygen stream to lose its
parallel form. As a result, the surface of the
cut is no longer clear and regular . This surface
will require machining or grinding to make it
suitable for welding.
29
F . BEVEL CUTTING
In this series of sketches a 3-inch (76.2mm)
carbon steel plate was beveled to show what
can happen when proper and improper
techniques are used in Bevel Cutting. More
preheat is required for beveling than for vertical
cutting. That’s because the angle of the tip to
the plate surface causes the heat to bounce
off. When selecting a tip for Bevel Cutting,
the depth of the cut rather than just the plate
thickness should be considered.
The PAN-1000 Panograph Torch Floater is
recommended for bevel cutting on both “flat”
and “wavy” material. The Panograph Torch
Floater maintains constant nozzle-to-work
distance which assures a uniform bevel!
30
1. This section is uniformly smooth on edges and
surface and represents a quality cut.
31
2. This section is very bad. (a) Very high preheat
has melted and rolled the top edge. (b) T ravel
speed was too slow causing gouges and slag
sticks to the bottom of the cut.
3. This section is slightly cupped just below the
top edge because of excess oxygen pressure.
The slight beading along the top edge
indicated that a little too much preheat was
used.
32
CUTTING NOTES:
33
MACHINE CUTTING TIP CHART
(Fill in figures from torch manufacturer’s literature.)
2
PLATE
THICKNESS
IN. MM.
1/16 2
1/8 3
1/4 6
3/8 10
1/2 13
3/4 19
125
1-1/4 32
1-1/2 38
251
2-1/2 64
376
4 102
5 127
6 152
7 178
8 203
9 229
10 254
11 279
12 305
TIP
SIZE
CUTTING O
PRESSURE
FUEL GAS
PRESSURE
KERF
CUTTING
WIDTH
SPEED
© WELD TOOLING CORP. 2008
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