AWS C5.

3:2000
An American National Standard

Recommended
Practices for
Air Carbon
Arc Gouging
and Cutting
Key Words —Air carbon arc, gouging, cutting, AWS C5.3:2000
recommended practices An American National Standard

Approved by
American National Standards Institute
November 21, 2000

Recommended Practices for

Air Carbon Arc Gouging and Cutting

Supersedes ANSI/AWS C5.3-91

Prepared by
AWS C5 Committee on Arc Welding and Cutting

Under the Direction of

AWS Technical Activities Committee

Approved by
AWS Board of Directors

Abstract
This publication establishes a method of conveying to the welder/operator the proper setup and use of air carbon arc
gouging and cutting. Instructions and procedures are supplied in detail so the welder/operator can establish the correct
air pressure, amperage, voltage, and techniques.

550 N.W. LeJeune Road, Miami, Florida 33126

 Statement on Use of AWS American National Standards
All standards (codes, specifications, recommended practices, methods, classifications, and guides) of the American
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International Standard Book Number: 0-87171-630-5
American Welding Society, 550 N.W. LeJeune Road, Miami, FL 33126
© 2001 by American Welding Society. All rights reserved
Printed in the United States of America
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This standard is subject to revision at any time by the AWS C5 Committee on Arc Welding and Cutting. It must be re-
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tions, or deletions) and any pertinent data that may be of use in improving this standard are required and should be
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 Personnel
AWS C5 Committee on Arc Welding and Cutting
B. L. Shultz, Chair The Taylor Winfield Corp.
J. R. Hannahs, 1st Vice Chair Consultant
N. E. Larson, 2nd Vice Chair Consultant
C. R. Fassinger, Secretary American Welding Society
*D. B. Arthur J. W. Harris-Welco
*E. R. Bohnart Welding Education and Consulting
H. A. Chambers TRW Nelson Stud Welding Division
C. Connelly Consultant
D. A. Fink The Lincoln Electric Company
I. D. Harris Edison Welding Institute
*R. T. Hemzacek Consultant
G. K. Hicken Sandia National Laboratory
*J. E. Hinkel The Lincoln Electric Company
D. B. Holliday Northrop Grumman Corp.
S. R. Potter Consultant
N. A. Sanders Hypertherm
R. L. Strohl Tweco-Arcair
E. G. Yevick Weld-Met International Group

AWS Subcommittee on Air Carbon Arc Cutting

R. L. Strohl, Chair Tweco-Arcair
C. R. Fassinger, Secretary American Welding Society
J. DeVito ESAB Wldg and Cutting Products
B. L. Shultz The Taylor Winfield Corp.
G. Snyder Tri-County Vocational Schools

*Advisor

iii
 Foreword
(This Foreword is not a part of AWS C5.3:2000, Recommended Practices for Air Carbon Arc Gouging and Cutting,
but is included for information purposes only.)
These recommended practices have been prepared by the Subcommittee on Air Carbon Arc Cutting, of the AWS Arc
Welding and Cutting Committee. It is important to recognize that this publication does not present the only possible
conditions for using the air carbon arc cutting process. The data given are presented merely as guides in establishing
operating conditions.
Comments and suggestions for the improvement of this standard are welcome. They should be sent to the Secretary,
AWS C5 Committee on Arc Welding and Cutting, American Welding Society, 550 N.W. LeJeune Road, Miami, FL
33126.

iv
 Table of Contents
Page No.
Personnel .................................................................................................................................................................... iii
Foreword......................................................................................................................................................................iv
List of Tables...............................................................................................................................................................vii
List of Figures.............................................................................................................................................................vii
1. General ..................................................................................................................................................................1
1.1 Scope.............................................................................................................................................................1
1.2 Description....................................................................................................................................................1
1.3 History ..........................................................................................................................................................1
1.4 Applications ..................................................................................................................................................1
2. Referenced Standards............................................................................................................................................2
3. Fundamentals of the Process .................................................................................................................................2
3.1 General..........................................................................................................................................................2
3.2 Power Sources...............................................................................................................................................2
3.3 Compressed Air ............................................................................................................................................2
3.4 Electrodes......................................................................................................................................................2
3.5 Gouging and Cutting Leads ..........................................................................................................................4
3.6 Manual Cutting Torches................................................................................................................................4
3.7 Mechanized Cutting Torches ........................................................................................................................4
3.8 Vacuum Gouging ..........................................................................................................................................6
4. Operating Techniques............................................................................................................................................6
4.1 Gouging ........................................................................................................................................................6
4.2 Cutting ..........................................................................................................................................................8
4.3 Washing.........................................................................................................................................................8
4.4 Beveling ........................................................................................................................................................8
5. Equipment Selection .............................................................................................................................................8
5.1 Cutting Torch ................................................................................................................................................8
5.2 Power Sources...............................................................................................................................................8
5.3 Mechanized Systems...................................................................................................................................10
6. Process Variables.................................................................................................................................................10
6.1 Introduction.................................................................................................................................................10
6.2 Electrode Diameter and Type......................................................................................................................10
6.3 Amperage....................................................................................................................................................10
6.4 Voltage ........................................................................................................................................................10
6.5 Air Pressure and Flow Rate ........................................................................................................................12
6.6 Travel Speed................................................................................................................................................12
6.7 Electrode Push Angle..................................................................................................................................12
6.8 Base Metals.................................................................................................................................................12
7. Advantages and Limitations................................................................................................................................13
7.1 Advantages..................................................................................................................................................13
7.2 Limitations ..................................................................................................................................................14

v
 Page No.
8. Troubleshooting...................................................................................................................................................14
9. Safe Practices ......................................................................................................................................................14
9.1 Introduction.................................................................................................................................................14
9.2 Noise ...........................................................................................................................................................14
9.3 Gases ...........................................................................................................................................................15
9.4 Radiant Energy............................................................................................................................................16
10. Bibliography........................................................................................................................................................16
Annex A—Commonly Used Metric Conversion..........................................................................................................17
Annex B—Safety References .......................................................................................................................................19
Annex C—Guidelines for Preparation of Technical Inquiries for AWS Technical Committees .................................21
AWS List of Documents on Arc Welding and Cutting .................................................................................................23

vi
 List of Tables
Table Page No.
1 Recommended Minimum Air Requirements .................................................................................................4
2 Recommended Number and Size of Gouging and Cutting Leads for Various Currents and Lengths ...........5
3 Suggested Current Ranges for Commonly Used Electrode Types and Sizes ................................................6
4 Mechanized CAC-A U-Groove Gouging Conditions ..................................................................................11
5 Automatic CAC-A J-Groove Operating Data ..............................................................................................11
6 Primary Process Variables............................................................................................................................12
7 Gouging Recommendations.........................................................................................................................13
8 Results of Corrosion Testing on Type 304L Stainless Steel ........................................................................14
9 CAC-A Troubleshooting ..............................................................................................................................15
10 Particulate Matter with Possible Significant Fume Concentration in the Arc Cutter’s Breathing Zone......16

List of Figures
Figure Page No.
1 Typical Arrangement for the Air Carbon Arc Cutting Process......................................................................3
2 How a Standard CAC-A Torch Works ...........................................................................................................3
3 Manual Torch .................................................................................................................................................5
4 Mechanized Cutting Torch .............................................................................................................................6
5 Flat Position Gouging ....................................................................................................................................7
6 Vertical Position Gouging ..............................................................................................................................7
7 Horizontal Position Gouging .........................................................................................................................7
8 Overhead Position Gouging ...........................................................................................................................7
9 Severing/Piercing with CAC-A......................................................................................................................9
10 Pad Washing with CAC-A .............................................................................................................................9
11 Methods of Beveling with CAC-A...............................................................................................................10

vii
 AWS C5.3:2000

Recommended Practices for

Air Carbon Arc Gouging and Cutting

1. General of the air jet in removing the molten metal. The air must
be capable of lifting the molten metal out and clear of the
1.1 Scope. This publication presents the basic concepts arc region before resolidification.
of the air carbon arc cutting (CAC-A)1 process to provide
a fundamental understanding of the process and its vari- 1.3 History. CAC-A was developed in the 1940s as an
ables. In addition, specific technical data are presented as extension of an existing process—carbon arc cutting.
a guide in establishing optimum operation of this process. Faced with the removal, in the flat position, of several
This standard makes use of the U.S. Customary Units. hundred feet of cracked stainless steel weld, a welding
Approximate mathematical equivalents in the Interna- engineer developed CAC-A. Carbon arc cutting was used
tional System of Units (SI) are provided for comparison to remove defective welds and rivet heads, but only in the
in parentheses ( ) or in appropriate columns in tables and overhead and vertical positions. The carbon arc melted
figures. Annex A is included to identify metric equivalents the metal and gravity moved the molten metal out of the
if the reader requires precise conversion information. area. It was reasoned that an air jet could provide the force
Safety and health issues and concerns are beyond the to remove the metal in the flat position.
scope of this standard and, therefore, are not fully ad- A direct current electrode negative (DCEN) carbon arc
dressed herein. Some safety and health information can was tried, and an air blast was provided by the second
be found in Section 9. Safety and health information is cutter with an air nozzle directed at the pool. This attempt
available from other sources, including, but not limited was not very successful because the arc was not stable.
to, ANSI Z49.1, Safety in Welding, Cutting, and Allied Direct current electrode positive (DCEP) was tried, and
Processes, and applicable federal and state regulations. the result made air carbon arc cutting practical. The basic
principle remains the same today, but the equipment and
1.2 Description. CAC-A is a physical means of metal applications have been improved and expanded.
removal in contrast to the oxidation reaction in oxyfuel In 1948, the first air carbon arc torch was introduced to
gas cutting (OFC). In the CAC-A, the intense heat of the the welding industry. No longer were two cutters needed.
arc between the carbon electrode and the workpiece melts The air was fed through the torch and out beneath the
a portion of the workpiece. Simultaneously, a jet of air is electrode at the correct location. This new tool was found
passed parallel to the arc and is of sufficient volume and to save time on backgouging of welds and removal of
velocity to blow away the molten material. The exposed cracks and other weld defects on carbon, alloy, and stain-
solid metal is then melted by the heat of the arc, and the less steels. Previously, this type of work had been done by
sequence continues. grinding or chipping. As the use of the CAC-A expanded,
CAC-A does not depend on oxidation to maintain the torches were designed for more efficient and cleaner metal
cut, so it is capable of cutting metals that OFC will not removal and for cutter comfort.
cut. The process is used successfully on carbon steel,
stainless steel, many copper alloys, and cast irons. The 1.4 Applications. The CAC-A process is used through-
melting rate is a function of current. The metal removal out industry in a variety of applications, such as metal
rate is dependent upon the melting rate and the efficiency fabrication and casting finishing, chemical and petro-
leum technology, construction, mining, general repair,
and maintenance. CAC-A torches and electrodes are used
1. CAC-A (Carbon Arc Cutting-Air) was formerly AAC (Air to create groove weld preparations in plates butted to-
Arc Cutting). gether. If the process is performed properly a minimal

1
AWS C5.3:2000

amount of additional cleaning and grinding is required. bon electrode, and cutting torch. Figure 1 shows the typi-
The CAC-A process can then be used to backgouge the cal arrangement for using this process.
joint to sound metal to ensure complete joint penetration. Except for special applications discussed later, CAC-
If during welding, a problem arises and an area of the A is used with DCEP (reverse polarity). The electrode
weld does not meet specifications, the CAC-A process should have a maximum extension of 7 in. (180 mm) from
can be used to remove the defective weld metal without the cutting torch, with the air jet between the electrode
damaging or detrimentally affecting the base metal. The and the workpiece. Although there is no minimum exten-
CAC-A process is used in the foundry industry to remove sion, care should be taken to prevent damage to the torch.
fins and risers from castings and then used to wash the Therefore 1-1/2 to 2 in. (38 to 51 mm) minimum exten-
contact areas smooth with the surface in preparation for sion is recommended. Progression should only be in the
shipment of the casting. The air carbon arc process pre- direction of air flow. The electrode push angle will vary,
sents great flexibility, efficiency, and cost effectiveness depending on the operation being performed. The cutter
when applied to practically any type of metal. Carbon should maintain the correct arc length to allow the air jet
steel, stainless steel, gray, malleable, and ductile iron, to properly remove the molten metal (see Figure 2).
aluminum, nickel, copper alloys, and other nonferrous
metals can be worked on with CAC-A. 3.2 Power Sources. Single-phase input machines with
low open-circuit voltage are generally inadequate for
CAC-A. However, any three-phase input welding power
source of sufficient capacity may be used, provided the
manufacturer recommends its use for CAC-A. The open-
2. Referenced Standards circuit voltage must be sufficiently higher than the re-
The following standards contain provisions which, quired arc voltage to allow for voltage drop in the circuit.
through reference in the text, constitute provisions of this The arc voltage used in air carbon arc gouging and cut-
AWS standard. For dated references, subsequent amend- ting ranges from 28 to 56 volts (V); thus, the open-circuit
ments to, or revisions of, any of these publications do not voltage should be at least 60 V. The actual arc voltage in
apply. However, parties to agreements based on this AWS air carbon arc gouging and cutting is governed to a large
standard are encouraged to investigate the possibility of extent by arc length and the application.
applying the most recent editions of the documents shown
3.3 Compressed Air. Standard compressed air is satis-
below. For undated references, the latest edition of the
factory for CAC-A. Between 80 psi (413.7 kPa) and 100 psi
standard referred to applies.
(690 kPa) pressures at the torch are normally used. Higher
(1) ANSI Z49.1, Safety in Welding, Cutting, and Al- pressures may be used, but offer little advantage in metal
lied Processes removal efficiency. Pressures as low as 40 psi (280 kPa)
(2) AWS F1.1, Methods of Sampling Airborne Partic- have been used with some manual torches in field appli-
ulates Generated by Welding and Allied Processes cations where only cylinders of compressed air are avail-
able. However, pressures this low are not recommended.
Available through:
Regardless of the pressure used with manual torches, the
American Welding Society
air hose supplying the concentric cable assembly should
550 N.W. LeJeune Road
have a minimum inside diameter (ID) of 3/8 in. (10 mm).
Miami, FL 33126
Mechanized torches with automatic arc length control
(3) OSHA Safety and Health Standards, 29CFR Part should have an air supply hose with a minimum ID of
1910 1/2 in. (13 mm).
Table 1 gives the consumption rate of compressed air
Available through:
for the various types of manual and mechanized torches,
Occupational Safety and Health Administration
as well as the compressor power rating required for inter-
200 Constitution Avenue NW
mittent and continuous use. Compressors should have a
Washington, DC 20210
standard receiver tank for the compressor rating. Refer to
Table 1 for suggested ASME receiver size for the torch
being used.

3. Fundamentals of the Process 3.4 Electrodes

3.1 General. CAC-A requires an arc to develop a mol- 3.4.1 DC Copper Coated Electrodes. This type is
ten pool on the workpiece. Compressed air is introduced most widely used because of its comparatively long elec-
to blow away this molten metal. The process requires a trode life, stable arc characteristics, and groove unifor-
welding power source, a source of compressed air, car- mity. These electrodes are made from a special mixture

2
 AWS C5.3:2000

Figure 1—Typical Arrangement for the Air Carbon Arc Cutting Process

Figure 2—How a Standard CAC-A Torch Works

3
AWS C5.3:2000

Table 1
Recommended Minimum Air Requirements
Recommended Compressor Rating

Air Pressure(1) Air Consumption Intermittent Use Continuous Use Receiver Size

Type of Torch psi kPa cfm L/min hp kW hp kW gal L

Light Duty(2) 40 280 8 227 0.5 0.4 1.5 1.1 60 227

General Duty(2) 80 550 25 708 5.0 3.7 7.5 5.6 80 303
Multipurpose(3) 80 550 33 934 7.5 5.6 10.0 7.5 80 303
Automatic(4) 60 414 46 1303 15.0 11.2 80 303
Notes:
(1) Pressure while torch is in operation.
(2) Accommodates flat electrodes.
(3) Generally considered a foundry torch.
(4) Requires some kind of mechanical manipulation.

of carbon and graphite with a suitable binder. Baking this graphite with a suitable binder. Rare-earth materials are
mixture at the appropriate temperature produces dense, incorporated to provide arc stabilization for cutting with
homogeneous graphite electrodes of low electrical resis- an alternating current. These electrodes, coated with a
tance which are then coated with a controlled thickness controlled thickness of copper, are available in the fol-
of copper. The copper coating improves electrical con- lowing diameters: 3/16, 1/4, 3/8, and 1/2 in. (5 mm, 6 mm,
ductivity providing more efficient, cooler operation and 10 mm, and 12 mm).
helps maintain electrode diameter at the point of the arc.
These electrodes are available in the following diameters: 3.5 Gouging and Cutting Leads. Table 2 gives the rec-
1/8, 5/32, 3/16, 1/4, 5/16, 3/8, 1/2, 5/8, and 3/4 in. (3 mm, ommended number and sizes of cutting leads for differ-
4 mm, 5 mm, 6 mm, 8 mm, 10 mm, 12 mm, 16 mm, and ent currents and lengths.
19 mm). 3.6 Manual Cutting Torches. A typical manual torch is
Jointed electrodes are available for operation without shown in Figure 3. The electrode is held in a rotating head
stub loss. They are furnished with a female socket and a which contains one or more air orifices, so that, regard-
matching male tenon and are available in the following less of the angle at which the electrode is set with respect
diameters: 5/16, 3/8, 1/2, 5/8, 3/4, and 1 in. (8 mm, 10 mm, to the cutting torch, the air jet remains in alignment with
12 mm, 16 mm, 19 mm, and 25 mm). the electrode. Cutting torches with two heads (the air jet
In addition to cylindrical electrodes, there are flat is on two sides of the electrode) or with a fixed angle be-
(rectangular) coated electrodes in the following sizes: tween the electrode and the holder, are preferred by some
5/32 × 3/8 and 3/16 × 5/8 in. (4 mm × 10 mm and 5 mm × users for special applications. Normally, cutting torches
16 mm). These are used for making rectangular grooves are air cooled. For high-current applications, water-cooled
and for the removal of weld reinforcements. cable assemblies are available and may be used with heavy-
duty torches.
3.4.2 DC Uncoated Electrodes. Of limited use, these
electrodes are generally used in diameters of less than 3.7 Mechanized Cutting Torches. There are two meth-
3/8 in. (10 mm). During cutting these electrodes are con- ods of controlling mechanized CAC-A torches. Either
sumed more rapidly than the coated electrodes. They are system is capable of making grooves of consistent depth
manufactured the same as the coated electrodes without to a tolerance of ± 0.025 in. (0.6 mm). These units are
the copper coating. Plain electrodes are available in the used where high quality, high productivity, or gouges in
following diameters: 1/8, 5/32, 3/16, 1/4, 5/16, 3/8, 1/2, 5/8, excess of 3 ft (900 mm) long are desired (see Figure 4).
3/4, and 1 in. (3 mm, 4 mm, 5 mm, 6 mm, 8 mm, 10 mm, They are as follows:
12 mm, 16 mm, 19 mm, and 25 mm).
3.7.1 Amperage Control. An amperage-controlled
3.4.3 AC Copper Coated Electrodes. The following type which maintains the arc current by amperage signals
electrodes are made from a special mixture of carbon and through solid-state controls. This type of system controls

4
 AWS C5.3:2000

Table 2
Recommended Number and Size of Gouging and
Cutting Leads for Various Currents(1), (2) and Lengths(3), (4)
25 feet (8 m) 50 feet (15 m) 100 feet (30 m) 150 feet (46 m) 200 feet (61 m) 250 feet (76 m)
Current
(Amperes) No. Size No. Size No. Size No. Size No. Size No. Size

100 1 4 1 3 1 2 1 1/0 1 2/0 1 4/0

200 1 3 1 2 1 1/0 1 3/0 1 3/0 3 3/0
300 1 2 1 2 1 3/0 2 2/0 2 4/0 4 4/0
400 1 2 1 1/0 1 4/0 2 4/0 3 4/0 5 4/0
500 1 1 1 2/0 2 2/0 2 4/0 4 4/0
600 1 1 1 3/0 2 3/0 2 4/0 5 4/0
800 1 1/0 2 2/0 2 4/0 4 4/0
1000 1 2/0 1 4/0 3 3/0 5 4/0
1200 1 3/0 2 4/0 3 4/0
1400 1 4/0 2 4/0 4 3/0
(6)1600(5) 2 3/0 4 3/0 4 4/0
1800 2 4/0 4 4/0
(6)2000(6) 3 4/0 5 4/0
Notes:
(1) Recommendations based on 4V, dc loss/100 ft (30 m).
(2) For ac use next higher size of cable.
(3) Length given is one half the sum of the electrode and the workpiece leads.
(4) Improper workpiece connection causes cable overheating; at least 1 in. (25 mm) of contact length should be used. Be sure the connection is tight.
(5) Over 1600 amps, a heavy-duty air-cooled cable should be used.
(6) Over 2000 amps, a heavy-duty water-cooled cable must be used.

Figure 3—Manual Torch

5
AWS C5.3:2000

3.8 Vacuum Gouging. In the late 1980s a new variation

of gouging was developed called vacuum gouging. This
process replaces the air jet used to evacuate the molten
slag from the groove area with a high-volume vacuum.
This process not only captures the slag and fume associ-
ated with the gouging process, but also reduces the noise
level created when performing the gouging process.
The vacuum gouging process is done using a specially
designed nozzle that attaches to the automatic gouging
head. By water cooling the nozzle and attached vacuum
hose, the slag and fume from the gouging process is pulled
by the vacuum into a capture drum. The slag is knocked
into the bottom of the catch tank, which is partially filled
with water, and the fume is caught in a filter before the
air is exhausted from the vacuum.
This new vacuum gouging system at present is limited
to automated gouging operations on flat plate or pressure
vessel circumferential seams.
Figure 4—Mechanized Cutting Torch

4. Operating Techniques
the electrode feed speed, which maintains the preset 4.1 Gouging. The electrode is gripped, as shown in Fig-
amperage and can be operated with constant-potential ure 3, so that a maximum of 7 in. (180 mm) extends from
power sources only. the cutting torch. For aluminum, this extension should be
reduced to 3 in. (76 mm). Table 3 shows suggested cur-
3.7.2 Voltage Control. A voltage-controlled type
rent ranges for various electrode types and sizes.
which maintains arc length by voltage signals through
The air jet should be turned on before striking the arc,
solid-state electronic controls. This type controls the arc
and the cutting torch should be held as shown in Figure
length determined by the preset voltage, and can be used
5. The torch should always be operated using the fore-
with constant-current power supplies only.
hand technique, i.e., the electrode and air jet pointed in
3.7.3 Dual System. A dual system is capable of oper- the direction of travel. Under proper operating condi-
ation by an internal selector switch in either of the modes tions, the air jet is expected to sweep beneath the elec-
described above. trode end and remove all molten metal. The arc may be

Table 3
Suggested Current Ranges for Commonly Used Electrode Types and Sizes
Electrode Diameter DC, DCEP Polarity AC Electrode

(in.) (mm) Minimum (amperes) Maximum (amperes) Minimum (amperes) Maximum (amperes)

1/8 3 30 60 200 250

5/32 4 90 150 300 400
3/16 5 200 250 325 425
1/4 6 300 400 350 450
5/16 8 350 450 500 600
3/8 10 450 600
1/2 13 800 100
5/8 16 1000 1250
3/4 19 1250 1600
1 25 1600 2200
3/8 Flat 10 250 450
5/8 Flat 16 300 500

6
 AWS C5.3:2000

Figure 5—Flat Position Gouging Figure 6—Vertical Position Gouging

struck by lightly touching the electrode to the workpiece.

The electrode should not be drawn back once the arc is
struck. The gouging technique is different from that of
arc welding because metal is removed instead of deposited.
A short arc should be maintained by progressing in the
direction of the cut fast enough to keep up with metal re-
moval. The steadiness of progression controls the smooth-
ness of the resulting cut surface.
For gouging in the vertical position, the cutting torch
should be held as shown in Figure 6. Gouging should be
done in a downhill direction, which permits gravity to as-
sist in removing the molten metal. Vertical gouging may
be done in the opposite direction, but it is more difficult.
Gouging in the horizontal position may be done either
to the right or to the left, but always with forehand goug-
ing. In gouging to the left, the cutting torch should be
held as shown in Figure 7. In gouging to the right, the Figure 7—Horizontal Position Gouging
cutting torch will be reversed to locate the air jet behind
the electrode.
When gouging in the overhead position, the electrode
and torch should be held at an angle that will prevent
molten metal from dripping on the cutter’s glove, as shown
in Figure 8.
The depth of the groove produced is controlled by the
travel speed. Grooves up to 1 in. (25 mm) deep may be
made. However, the deeper the groove, the more experi-
ence is required of an operator to produce an acceptable
groove. Slow travel speeds produce a deep groove. Fast
speeds will produce shallow grooves. The width of the
groove is determined by the size of the electrode used
and is usually about 1/8 in. (3 mm) wider than the elec-
trode diameter. Wider grooves may be made with an
electrode that is oscillated with a circular or weave motion.
When gouging, a push angle of 65 degrees from the
surface of the workpiece is used for most applications. A
steady rest is recommended in gouging to ensure a smoothly Figure 8—Overhead Position Gouging

7
AWS C5.3:2000

gouged surface. It is particularly advantageous for use in 3/8 in. (9.5 mm) and 5/8 in. (15.9 mm) flat electrodes.
the overhead position. Proper travel speed depends on the Maximum 450 amperes.
size of the electrode, base metal, cutting amperage, and air (2) Medium-Duty General Purpose Torch—accepts
pressure. Proper speed, which produces a smooth hissing 5/32 in. (3.97 mm) to 3/8 in. (9.5 mm) round electrodes and
sound, will result in a smooth gouge. 3/8 in. (9.5 mm) flat electrodes. Maximum 1000 amperes.
(3) Heavy-Duty General Purpose Torch—accepts
4.2 Cutting. Figure 9 shows the electrode in position for
5/32 in. (3.97 mm) to 1/2 in. (12.7 mm) round electrodes
cutting. In general, the cutting technique is the same as for
and 3/8 in. (9.5 mm) and 5/8 in. (15.9 mm) flat electrodes.
gouging, except that the electrode is held at a steeper an-
Maximum 1000 amperes.
gle; that is, with a push angle between 10 and 20 degrees.
(4) Extra-Heavy-Duty General Purpose Torch—
For cutting thick nonferrous metals, the electrode accepts 5/32 in. (3.97 mm) to 5/8 in. (15.9 mm) round
should be held perpendicular to the workpiece surface, electrodes and 3/8 in. (9.5 mm) and 5/8 in. (15.9 mm) flat
with the air jet in front of the electrode in the direction of electrodes. Maximum 1250 amperes.
travel. With the electrode in this position, the metal may
(5) Foundry-Heavy-Duty Torch—General foundry
then be cut by moving the arc up and down through the
work and heavy-duty fabrication. Limited to 1600 amps
metal with a sawing motion.
with air-cooled cables and 2000 amps with water-cooled
4.3 Washing. In using the air carbon arc cutting process cables.
for removing metal from large areas, such as the removal (6) Mechanized Gouging Torches—Edge prepara-
of surfacing metal and of riser pads on castings, the proper tions and backgouging, high quality and high productivity
position of the electrode is shown in Figure 10. The elec- uses. Used with 5/16 in. (8 mm) through 3/4 in. (19 mm)
trode should be oscillated from side to side while pushing jointed carbon electrodes.
forward at the depth desired. In pad washing operations,
5.2 Power Sources. Any three-phase input welding power
a push angle of 20 to 75 degrees from the vertical is used.
source of sufficient capacity may be used for the air carbon
The 75 degree angle is used for light finishing passes,
arc gouging process, providing the manufacturer recom-
while the steeper angles allow deeper rough cutting to be
mends its use for CAC-A. However, be sure the open-circuit
done with greater ease.
voltage (OCV) is high enough to allow for voltage drop in
Particularly suited for this application are cutting the circuit. The arc voltage used in air carbon arc gouging
torches with fixed angle heads that hold the electrode at the and cutting ranges from 28 to 56 V; thus the open-circuit
correct angle. With other types of torches, care should be voltage should be at least 60 V. Some constant potential
taken to keep the air jet behind the electrode. The steadi- power sources require very high OCV to operate CAC-A
ness of the cutter determines the smoothness of the sur- equipment. Single-phase input power sources require
face produced. very high OCV to operate CAC-A equipment. Single-
4.4 Beveling. One beveling method is to hold the elec- phase input power sources are generally inadequate for
trode, as in Figure 11(A), with the torch parallel to the this process. Power sources being used in conjunction
edge being beveled, and a work angle equal to the angle with mechanized cutting and other applications requiring
of the bevel to be produced. The air jet is between the maximum arc time should be rated 100% duty cycle for
electrode and workpiece surface. The second method is the required amperage.
to hold the electrode as in Figure 11(B) with the elec- 5.2.1 Power Source Preferences. Choice of DC
trode parallel to the edge being beveled and the electrode power supply mode depends upon electrode size:
angle at 35 degrees. The air jet is between the electrode (1) DC—(Direct Current) Constant Current (Motor
and the workpiece surface. generator, transformer-rectifier, or resistor grid unit).
Preferred power source for all electrode sizes.
(2) DC—Constant Potential (Motor generator or
5. Equipment Selection transformer rectifier). Usable only for 5/16 in. (7.9 mm)
and larger electrodes. May cause carbon deposits with
5.1 Cutting Torch. Chosen for the job being done, small electrodes. Not suitable for automatic torches with
torches range from light-duty farm and body shop sizes voltage control only.
to extra-heavy-duty foundry torches. The following is a (3) AC/DC Transformer-Rectifier. Direct current (dc)
guide for torch use: supplied from three phase transformer-rectifier supplies
General Purpose Torches: is satisfactory, but dc from single phase supplies gives
unsatisfactory arc characteristics. Alternating current
(1) Light-Duty General Purpose Torch—accepts (ac) output from ac/dc units is satisfactory, provided ac
1/8 in. (3.2 mm) to 1/4 in. (6.5 mm) round electrodes and electrodes are used.

8
 AWS C5.3:2000

Figure 9—Severing/Piercing with CAC-A

Figure 10—Pad Washing with CAC-A

9
AWS C5.3:2000

are particularly adaptable to producing long gouges in

flat workpieces with a moving gouging apparatus, and
for circular gouges in pipe and tanks with the gouging
apparatus remaining stationary. They produce a very con-
sistent U-groove configuration and can control depth of
the groove to within 0.025 in. (0.6 mm). Tables 4 and 5 give
typical operating conditions for both U- and J-grooves.

6. Process Variables
6.1 Introduction. The CAC-A process is sensitive to
improper operation, as is any thermal cutting process.
Variables can cause changes in the finished gouge that
range from indiscernible to unacceptable results. Primary
variables that require attention, along with the functions
resulting from those variables, are listed in Table 6.

6.2 Electrode Diameter and Type. This is the most

dominant factor in determining the size of the groove.
The proper choice of electrode can affect productivity,
Figure 11—Methods of Beveling with CAC-A groove quality, and metal removal rates. The width of the
groove will be approximately 1/8 in. (3 mm) wider than
the diameter of the electrode. In choosing the proper elec-
trode, the size of the desired groove should be the decid-
ing factor, with available power dictating the maximum
(4) AC Constant Current (Transformer). Recom- electrode diameter. As an example, a 1/2 in. (12 mm)
mended for ac electrodes only. wide, 1/4 in. (6 mm) deep groove 10 in. (254 mm) long
5.3 Mechanized Systems. Mechanized systems are used could be made manually in two passes using a 1/4 in.
more in the fabrication industry. These systems offer a (6 mm) diameter electrode or in one pass with a 3/8 in.
high-quality, high-productivity alternative to manual cut- (9.5 mm) diameter electrode. In the former, the effective
ting. There are two types of systems to be considered, both gouging rate would be 10 in. (254 mm) per minute per
operating on a signal from the arc to control the gouging; pass. Therefore the effective travel speed is 5 in. (127 mm)
dual signal system and single-signal system. per minute (10 IPM [254 mm] divided by 2 passes). The
travel speed or gouging rate for 3/8 in. (10 mm) is 17 in.
5.3.1 Dual Signal System. With this type of mecha- (432 mm) per minute. This is more than a 200% increase
nized system, either constant current or constant poten- in gouging rate and will offset the additional electrode
tial power supplies can be used. When utilizing constant cost. Mechanized systems even further increase the pro-
current, the arc length is maintained through a voltage ductivity rate due to the finite control of the arc voltage.
signal system. A predetermined voltage setting is set on
the system controller, which then advances or retracts the 6.3 Amperage. The gouging amperage determines the
electrode through a stepping motor to maintain the arc melting rate of the process. It is determined by the elec-
length. On a constant potential power source, amperage trode size. If the amperage is set too low for the electrode
sensing controls the feeding or retracting of the electrode size, the melting rate of the base metal will be inadequate,
to maintain the desired arc current. and free-carbon deposits will occur. A setting too high,
5.3.2 Single-Signal System (Voltage Control Only). while melting the base metal, will cause rapid deterio-
This type system also maintains arc length through a volt- ration of the electrode with subsequent reduction in metal
age signal as above, but will not operate with an amperage removed per electrode. This condition can also substan-
signal. This type of system operates only on a CC power tially reduce torch life.
source.
6.4 Voltage. Voltage is determined by the arc length and
5.3.3 Advantages. Mechanized CAC-A systems the current flow through the arc. CAC-A generally re-
offer substantial improvements in both productivity and quires a higher voltage than most welding processes. This
quality. They are capable of out-of-position gouging and requirement limits proper operation to power sources with

10
 AWS C5.3:2000

Table 4
Mechanized CAC-A U-Groove Gouging Conditions
Electrode Diameter Desired Depth Travel Speed
DCEP Polarity
(in.) (mm) (in.) (mm) (in./min) (mm/min) (amperes)

5/16 8 1/8 3 65 1650 400

3/16 5 45 1140
1/4 6 36 9140
5/16 8 33 840
7/16 11 22 560

3/8 10 1/8 3 70 1780 500

3/16 5 44 1120
1/4 6 35 890
3/8 10 20 510
9/16 14 17 430

1/2 13 1/8 3 96 2440 850

1/4 6 57 1450
3/8 10 35 890
1/2 13 24 610
3/4 19 18 460

5/8 16 1/4 6 72 1830 1250

3/8 10 48 1220
1/2 13 37 940
5/8 16 30 760
7/8 22 20 510

3/4 19 3/8 10 42 1070 1400

1/2 13 34 860
5/8 16 27 690
3/4 19 22 560
1 24 18 460
General Note: If the groove depth is 1-1/2 times the electrode diameter being used, make two or more passes.

Table 5
Automatic CAC-A J-Groove Operating Data
Material Overall
Size Electrode Data Electrode Overhang (in.) Pass Power Data Travel Speed per Minute Pass Speed

Size Stickout 1 2 3 1 2 3
in. (mm) in. (mm) Angle in. (cm) in. (mm) in. (mm) in. (mm) Amps Volts in. (cm) in. (cm) in. (cm) in. (cm)

3/8 (10) .063 (1.6) 450 42 65 (165) . 65 (165)

1/2 (13) 5/16 (8) 45 4 (10) .063 (1.6) 450 42 35 (89) . 35 (89)
5/8 (16) 3/8 (10) 45 4 (10) .063 (1.6) .063 (1.6) 600 42 50 (127) 50 (127) .25 (64)
3/4 (19) 3/8 (10) 45 4 (10) .063 (1.6) .063 (1.6) 600 42 37 (94) 37 (94) 18.5 (47)
0.1 (25) 5/8 (16) 45 4 (10) .125 (3.2) .125 (3.2) 1250 42 40 (102) 40 (102) . 20 (51)
1.5 (38) 5/8 (16) 45 4 (10) .063 (1.6) .063 (1.6) .063 (1.6) 1250 42 47 (119) 47 (119) 47 (119) .16 (41)
0.2 (50) 5/8 (16) 45 4 (10) .125 (3.2) .125 (3.2) .125 (3.2) 1250 42 28 (71) 28 (71) 28 (71)0 9.5 (10)

11
AWS C5.3:2000

electrode size should be used, or a move to mechanized

Table 6 gouging should be considered. Attempting a groove too
Primary Process Variables deep for the electrode diameter creates a poor quality
groove that requires excessive grinding.
Variable Function

Electrode diameter Determines the size of the groove. 6.7 Electrode Push Angle. The electrode push angle is
the most forgiving of the process variables. When goug-
Amperage Determined by the diameter of electrode ing manually, a greater angle tends to produce a more Vee
being used. It is the current flow performing
shaped groove. With the mechanized system, a greater
the melting of the base metal
angle will produce a slightly deeper groove with the same
Voltage The electric potential behind the amperage, travel speed as a groove made with a lesser angle.
or the arc force. Determined by arc length
on CC power supplies and set on CV power 6.8 Base Metals
supplies.

Air pressure The medium for removal of the molten 6.8.1 Gouging Recommendations. Gouging recom-
and flow rate metal. mendations are provided in Table 7.
Travel speed Determines the depth and quality of finished 6.8.2 Effects of the Cutting Process on Base Metals.
grooves.
To avoid difficulties with carburized metal, users of the
Electrode travel Can determine groove shape. CAC-A process should be aware of the metallurgical events
and work angle that occur during gouging and cutting. With DCEP, and
Electrode Affects metal removal rates and quality of
the corresponding half cycle of ac, the current flow car-
extension groove. ries ionized carbon atoms from the electrode to the base
metal. The free carbon particles are rapidly absorbed by
Base metal Determines selection of parameters for the melted base metal. Increased carbon can lead to in-
other variables.
creased hardness and possible cracking. Since this absorp-
tion cannot be avoided, it is important that all carburized
molten metal be removed from the cut surface, preferably
by the air jet.
When the CAC-A process is used under improper con-
high enough open-circuit voltage to maintain a 28 V oper-
ditions, the carburized molten metal left on the surface
ating minimum. Inadequate voltage can create a sputter-
may usually be recognized by its dull gray-black color.
ing arc or actually prevent arc establishment. This results
This is in contrast to the bright blue color of the properly
in uneven grooves with a high probability of free-carbon
made groove. Inadequate air flow may leave small pools
deposits, requiring excessive grinding to remove.
of carburized metal in the bottom of the groove. Irregular
6.5 Air Pressure and Flow Rate. The air jet is the me- electrode travel, which is particularly true for manual
dium for the removal of the molten metal. Both adequate gouging, may produce ripples in the groove wall that tend
pressure and flow rate are required to obtain the proper to trap the carburized metal. Finally, an improper elec-
results. This variable is probably one of the most abused trode push angle may cause small beads of carburized
of all the variables discussed. The flow rate in cubic feet metal to remain along the edge of the groove.
per minute (cfm) is as important as the air pressure. The The effect of carburized metal on the cut surface dur-
pressure is the variable that determines the velocity of the ing subsequent welding depends on many factors, includ-
air that moves the molten metal out of the groove area. If ing the amount of carburized metal present, the welding
there is not enough flow to lift the molten metal out of process to be employed, the kind of base metal, and the
the groove, the air jet cannot remove the molten metal, re- weld quality required. Although it may seem that filler
sulting in excessive slag adhesion and unnecessary grinding metal deposited on the surface during welding should as-
to clean the groove. This is necessary to ensure that the similate small pools or beads of carburized metal, experi-
air supply system possesses an adequate receiver (reservoir) ence with steel base metals shows that traces of metal
in order to maintain the required flow rate (see Table 1). containing approximately 1% carbon may remain along
the weld interface. The effect of these carburized depos-
6.6 Travel Speed. Travel speed is the variable that di- its become more significant with demands for increasing
rectly affects the depth of the gouge as well as the result- weld strength and toughness.
ing quality of the groove. The faster the travel for any There is no evidence that the copper from copper-
given diameter electrode, the shallower the gouge. If the coated electrodes is transferred to the cut surface in base
travel speed is too fast for the cutter’s comfort, a smaller metal, except when the process is improperly used.

12
 AWS C5.3:2000

Table 7
Gouging Recommendations
Base Metal Recommendations

Carbon steel and low-alloy steel, such as Use dc electrodes with DCEP (electrode positive). AC electrodes with an AC transformer
ASTM A 514 and A 517 can be used, but for this application, ac is only 50% as efficient as dc.

Stainless steel Same as for carbon steel.

Cast iron, including gray, malleable, and Use of 1/2 in. (12 mm) or larger electrodes at the highest rated amperage is necessary.
ductile iron. There are also special techniques that need to be used when gouging these metals. The
push angle should be at least 20 degrees and depth of the cut should not exceed 1/2 in.
(13 mm) per pass.

Copper alloys Use dc electrodes with DCEN at maximum amperage rating of the electrode or use ac
electrodes with ac.

Aluminum bronze and aluminum nickel Use dc electrodes with DCEN.

bronze (special naval propeller alloy)

Nickel alloys (nickel content is over 80%) Use ac electrodes with ac.

Nickel alloys (nickel content less than 80%) Use ac electrodes with DCEP.

Magnesium alloys Use ac electrodes with DCEP. Before welding, surface of groove should be wire
brushed.

Aluminum Use dc electrodes with DCEP. Wire brushing with stainless wire brushes is mandatory
prior to welding. Electrode extension (length of electrode between electrode torch and
workpiece) should not exceed 3 in. (76 mm) for good quality work. DC electrodes with
DCEN can also be used.

Titanium, zirconium, hafnium, and their Should not be cut or gouged in preparation for welding or remelting without subsequent
alloys mechanical removal of surface layer from cut surface.

Carburized metal on the cut surface may be removed is less distorted than oxyfuel gas cutting. The machin-
by grinding, but it is much more efficient to conduct air ability of low carbon and nonhardenable steels is not af-
carbon arc gouging and cutting properly within prescribed fected by the CAC-A process. With cast iron and high-
conditions to completely avoid the retention of undesir- carbon steels, however, this process may make the cut
able metal. surface extremely hard. Nevertheless, because the hard-
Studies have been conducted on stainless steel to de- ened zone is shallow (approximately 0.06 in. [1.5 mm]), a
termine whether air carbon arc gouging, carried out in cutting tool is able to penetrate the hardened zone and re-
the prescribed manner, would adversely affect corrosion move this layer.
resistance. Results of the studies are shown in Table 8.
Type 304L stainless steel was welded using several pro-
cesses. Backgouging of the joint was performed by air 7. Advantages and Limitations
carbon arc gouging and by grinding. Specimens from the
joints were subjected to the boiling 65% nitric acid test. 7.1 Advantages
Corrosion rates typical for Type 304L stainless steel
7.1.1 Fast. Gouging with CAC-A is five times faster
were obtained, and the results showed no significant dif-
than chipping; it gouges a groove 3/8 in. (10 mm) deep at
ference in the corrosion rates of welds prepared by CAC-A
over 2 feet per minute (0.6 M/M).
and those prepared by grinding. Had any appreciable carbon
absorption occurred, the corrosion rates for welds back- 7.1.2 Easily Controllable. CAC-A removes defects
gouged by CAC-A would have been significantly higher. with precision. Defects are clearly visible in the groove
Compared to oxyfuel gas cutting, CAC-A is a higher and may be followed with ease. The depth of the cut is
energy process which results in lower heat input to the easily regulated, and slag does not deflect or hamper the
base metal. Therefore, a workpiece gouged or cut by CAC-A cutting action.

13
AWS C5.3:2000

Table 8
Results of Corrosion Testing on Type 304L Stainless Steel
Corrosion Rate (per month)
Specimen
Identification Welding Process Welding Position Root Preparation in. mm

HC1 GMAW Horizontal CAC-A Gouging 0.000593 0.01505

HC2 GTAW Horizontal CAC-A Gouging 0.000594 0.01509
HG1 GMAW Horizontal Grinding 0.000646 0.01640
HG2 GTAW Horizontal Grinding 0.000618 0.01570
VC1 GMAW Vertical CAC-A Gouging 0.000686 0.01742
VC2 SMAW Vertical CAC-A Gouging 0.000627 0.01593
VG SMAW Vertical Grinding 0.000667 0.01695
OG SMAW Overhead Grinding 0.000632 0.01605
OC SMAW Overhead CAC-A Gouging 0.000645 0.01638

7.1.3 Low Equipment Cost. No gas cylinders or reg- 9. Safe Practices

ulators are necessary except in field operations.
9.1 Introduction. The general subject of safety and safe
7.1.4 Economical to Operate. No oxygen or fuel gas
practices in welding and thermal cutting processes, such
is required with CAC-A. The welder or welding operator
as CAC-A, is covered in ANSI Z49.1, Safety in Welding,
may also do the gouging or cutting.
Cutting, and Allied Processes. Air carbon arc cutters and
7.1.5 Easy to Operate. Welders operate the equip- their supervisors should be familiar with the practices
ment after a few minutes of instruction and become pro- discussed in these documents. Other safety sources are
ficient in a few days. The torch contains an air-control listed in Annex B.
valve and rotating nozzle that permits changing the elec- In addition, there are other potential hazard areas in arc
trode position to suit the job while maintaining alignment welding and cutting (other than fumes, gases, and radiant
of the air jet. energy), such as noise and improper use of pressure regu-
lators, which warrant consideration. Those areas associated
7.1.6 Compact. The torch is not much larger than a
with CAC-A are briefly discussed in this section.
shielded metal arc electrode holder.
7.1.7 Versatile. CAC-A is used anywhere it is possi- 9.2 Noise. Excessive noise is a known health hazard.
ble to weld. It may be operated in spaces too restricted to Exposure to excessive noise can cause a loss of hearing.
accommodate a chipping hammer or an oxyfuel gas cut- The loss of hearing can be either full or partial, and tem-
ting torch. It requires no difficult adjustments for use on porary or permanent. In welding, cutting, and allied op-
different metals. erations, noise may result from the process, the power
7.1.8 Cuts Cleanly. The resulting surface of CAC-A source, or other equipment. Air carbon arc and plasma
is clean and smooth. Welding may generally be performed arc are examples of processes which are frequently noisy.
with a minimum of grinding or cleaning. Engines of engine-driven generators may also be quite
noisy.
7.2 Limitations Excessive noise adversely affects hearing capability.
(1) Other cutting processes are better for severing. This adverse effect upon hearing capability may be a tem-
(2) CAC-A requires a large volume of compressed air. porary threshold shift from which ears may recover if re-
(3) CAC-A increases the surface hardness on cast iron moved from the noise source. However, if a person is
and air hardenable metals. This may be objectionable. exposed to the same noise level for a longer time, then
(4) The CAC-A process is accompanied by noise, the loss of hearing may become permanent. The time re-
fumes, and a discharge of sparks and molten metal. quired to develop permanent hearing loss depends upon
factors such as individual susceptibility, noise level, and
exposure time. In addition, there is evidence that exces-
8. Troubleshooting sive noise affects other bodily functions and behavior.
The CAC-A problems versus solutions shown in A direct method to protect against excessive noise is
Table 9 can be used for troubleshooting. to reduce the intensity of the source. Another method is

14
 AWS C5.3:2000

Table 9
CAC-A Troubleshooting
Problem Cause/Remedy

Large free-carbon deposit at The operator either neglected to turn on the air jet before striking the arc, or the torch was located
the beginning of the groove. improperly. The air should be turned on before striking the arc and should flow between the elec-
trode and the workpiece behind the electrode in the direction of travel.

An unsteady arc, causing the The amperage was insufficient for the electrode diameter used (see Table 3). While the minimum
cutter to use a slow travel recommended amperage may be sufficient, it does require a higher degree of operator skill. The mid-
speed even on shallow dle of the range is much more efficient. If the desired amperage cannot be obtained from the avail-
grooves. able power source, greater efficiency would be obtained by using a smaller diameter electrode.

Erratic groove with the arc The process was apparently used with DCEN (electrode negative). Direct current electrodes should
wandering from side to side be used with DCEP on all metals, with the exception of a few copper alloys.
and with the electrode heating
rapidly.

Intermittent arc action The travel speed was too slow in manual gouging. Generally, the operator has fixed his or her posi-
resulting in an irregular tion by setting a hand on the workpiece. Since the speed of air carbon arc gouging is much faster
groove surface. than shielded metal arc welding, friction between the gloved hand and the workpiece may cause an
erratic forward motion. This causes the arc length between the electrode and workpiece to become
too large to maintain the arc. The cutting operator should assume a comfortable position so that his
or her arms can move freely and the gloves do not drag on the work. If mechanized equipment is
involved, check Tables 4 and 5 for proper operating conditions.

In gouging, carbon deposits The electrode has shorted out on the workpiece. In manual gouging, this condition is caused by
left at intervals along the using travel speed excessive for the amperage used and for the depth of the groove being made. In
groove; in pad washing, mechanized operations, it is caused either by excessive travel speed or by using a flat-curve constant
carbon deposits at various potential power source for a small diameter electrode of 5/16 in. (8 mm). In pad washing, this short-
spots on the washed surface. ing out is caused by holding the electrode at too large a push angle. An electrode push angle of 20 to
75 degrees from the vertical is recommended. A larger angle increases the arcing area, which
reduces the current density. This reduction in arc current density requires a decrease in arc length, to
the point of short circuiting. Care must be taken to maintain the proper arc gap.

Irregular groove, too deep, The operator was unsteady. The operator should relax and assume a comfortable position when
then too shallow. gouging.

Slag adhering to the edges Slag ejection was inadequate. For adequate slag ejection, proper air pressure and flow rate should be
of the groove. used. Air pressure, between 80 and 100 psi (550–690 kPa), may not effectively eject all of the slag if
the volume is insufficient. To deliver adequate volume, the air hose feeding the concentric cable
assembly should have a minimum ID of 3/8 in. (10 mm) for manual torches. For mechanized torches
that do not require a concentric cable, the minimum hose ID should be 1/2 in. (13 mm).

to shield the source, but this has limitations. The acousti- 9.3 Gases. The major toxic gases associated with the air
cal characteristics of a room will also affect the level of carbon arc process are ozone, nitrogen dioxide, and car-
noise. When engineering control methods fail to reduce bon monoxide. Phosgene gas could be present as a result
the noise, personal protective devices such as ear muffs of thermal or ultraviolet decomposition of chlorinated
or ear plugs may be employed. Generally, these devices hydrocarbon cleaning agents or suspension agents used
are only accepted when engineering controls are not fully in some aerosol anti-spatter agents or paints. Degreasing
effective. or other operations involving chlorinated hydrocarbons
The permissible noise exposure limits can be found in should be so located that vapors from these operations
the CFR Title 29, Chapter XVII, Part 1910. Additional cannot be reached by radiation from the arc.
information may be found in the Threshold Limit Values
for Chemical Substances and Physical Agents Biological 9.3.1 Ozone. The ultraviolet light emitted from the arc
Exposure Limits. Information on obtaining these docu- acts on the oxygen in the surrounding atmosphere to pro-
ments can be found in Annex B. duce ozone. The amounts of ozone produced will depend

15
AWS C5.3:2000

upon the intensity and the wavelength of the ultraviolet ministration. Compliance with these levels can be tested
energy, the humidity, the amount of screening afforded by by a sampling of the atmosphere under the cutter’s hel-
the fume, and other factors. The ozone concentration will met or in the immediate vicinity of the cutter’s breathing
generally be increased with an increase in current and when zone. Samples should be in accordance with AWS F1.1,
aluminum is cut or gouged. The concentration can be con- Methods for Sampling Airborne Particulates Generated
trolled by natural ventilation, local exhaust ventilation, or by Welding and Allied Processes.
by respiratory protective equipment described in ANSI
Z49.1. 9.4 Radiant Energy. Any person within the immediate
vicinity of the cutting arc should have adequate protec-
9.3.2 Nitrogen Dioxide. Some tests have shown that tion from radiation produced by the cutting arc. The filter
high concentrations of nitrogen dioxide are found only shade recommended for CAC-A is a shade twelve (12) or
close to the arc. Natural ventilation reduces these con- greater. For less than 500 A 12 is acceptable; for greater
centrations quickly to safe levels in the cutter’s breathing than 500 amps use a shade fourteen (14). Leather or wool
zone, so long as the cutter keeps his or her head out of clothing that is dark in color is recommended to better
the fume plume. withstand the vigors of radiation, better resist burning,
and to reduce ultraviolet burns to the neck and face be-
9.3.3 Metal Fumes. The fumes generated by the
neath the helmet.
CAC-A process can be controlled by natural ventilation,
local exhaust ventilation, or by respiratory protective
equipment described in ANSI Z49.1. The method of ven-
tilation required to keep the level of particulate and gases
in the operator’s breathing zone within acceptable con- 10. Bibliography
centrations is directly dependant upon a number of fac-
(1) American Welding Society. Welding Handbook,
tors, among which are the metal being cut or gouged, the
Vol. 2, 8th Ed., 489–496; Miami: American Welding
size of the work area, and the degree of confinement or
Society, 1991.
obstruction to the normal air movement where the opera-
(2) Christensen, L. J. “Air carbon arc cutting.” Weld-
tion is taking place.
ing Journal 52(12): 782–791; 1973.
Each operation should be evaluated on an individual
basis in order to determine what will be required. See (3) Franz, R. “Maintenance welding for excavators.”
Table 10 for the specific particulate matter that may be Welding Design & Fabrication 45(10): 49–50 1972.
present for cutting specific base metals. Acceptable lev- (4) Hard, A. R. “Exploratory tests of the air carbon
els of particulate matter associated with cutting and des- arc cutting process.” Welding Journal 33(6): Res. Suppl.
ignated as time-weighted average threshold limit values 261-s to 264-s, 1954.
(TLVs) and ceiling values have been established by the (5) Hause, W. O. “What you should know about air
American Conference of Governmental Industrial Hy- carbon arc metal removal.” Welding Design & Fabrication
gienists and by the Occupational Safety and Health Ad- 51(1): 52–56, 1978.
(6) Marshall, W. J. et al. “Optical radiation levels pro-
duced by air carbon arc cutting processes.” Welding
Journal 59(3): 43–46, 1980.
(7) Oliver, T. P. and Sanderson, J. T. “Arc air gouging:
the hazards and their control.” Journal of the Society of
Table 10
Occupational Medicine 23(4): 114–119, 1973.
Particulate Matter with Possible
(8) Panter, D. “Air carbon arc gouging.” Welding
Significant Fume Concentration
Journal 56(5): 32–37, 1977.
in the Arc Cutter’s Breathing Zone
(9) Prager, M. and Thiele, E. W. “Welding a copper
Base Metal Particulate Matter nickel clad ship-mariner II.” Welding Journal 58(7):
17–24, 1979.
Aluminum and aluminum alloys Al, Mg, Mn, Cr, Si (10) Ridal, E. J. “Preparation for welding by air carbon
Magnesium alloys Mg, Al, Zn arc gouging.” Welding & Metal Fabrication 45(6): 347–
Copper and copper alloys Cu, Be, Zn, Pb, Sn, Si
Nickel and nickel alloys Ni, Cu, Cr, Fe 353, 356–362, 1977.
Titanium and titanium alloys Ti, Al, V (11) Soisson, L. and Henderson, J. “J-groove edge prep
Austenitic stainless steels Cr, Ni, Fe, Mn comes easy with AAC.” Welding Design & Fabrication,
Carbon steels(1) Fe, Cu, Mn 57(7): 53–55, 1983.
Note: (12) Soisson, L. “Automatic AAC reduces edge prepa-
(1) Also Cd, Sn, and Zn for plated base metals. ration time.” Welding Journal 65(5): 67–72, 1986.

16
 AWS C5.3:2000

Annex A
Commonly Used Metric Conversions
(This Annex is not a part of AWS C5.3:2000, Recommended Practices for Air Carbon Arc Gouging and Cutting, but
is included for information purposes only.)

Commonly Used Metric Conversions

(Inch–Millimeter Conversion)
1 in. = 25.4 mm exactly
To convert inches to millimeters, multiply the inch value by 25.4.
To convert millimeters to inches, divide the millimeter value by 25.4.
Inch Inch

Fractional Decimal Millimeter Fractional Decimal Millimeter

1/64 0.015 625 0.396 875 33/64 0.515 625 13.096 875
1/32 0.031 250 0.793 750 17/32 0.531 250 13.493 750
3/64 0.046 875 1.190 625 35/64 0.546 875 13.890 625
1/16 0.062 500 1.587 500 9/16 0.562 500 14.287 500
5/64 0.078 125 1.984 375 37/64 0.578 125 14.684 375
3/32 0.093 750 2.381 250 19/32 0.593 750 15.081 250
7/64 0.109 375 2.778 125 39/64 0.609 375 15.478 125
1/8 0.125 000 3.175 000 5/8 0.625 000 15.875 000
9/64 0.140 625 3.571 875 41/64 0.640 625 16.271 875
5/32 0.156 250 3.968 750 21/32 0.656 250 16.668 750
11/64 0.171 875 4.365 625 43/64 0.671 875 17.065 625
3/16 0.187 500 4.762 500 11/16 0.687 500 17.462 500
13/64 0.203 125 5.159 375 45/64 0.703 125 17.859 375
7/32 0.218 750 5.556 250 23/32 0.718 750 18.256 250
15/64 0.234 375 5.953 125 47/64 0.734 375 18.653 125
1/4 0.250 000 6.350 000 3/4 0.750 000 19.050 000
17/64 0.265 625 6.746 875 49/64 0.765 625 19.446 875
9/32 0.281 250 7.143 750 25/32 0.781 250 19.843 750
19/64 0.296 875 7.540 625 51/64 0.796 875 20.240 625
5/16 0.312 500 7.937 500 13/16 0.812 500 20.637 500
21/64 0.328 125 8.334 375 53/64 0.828 125 21.034 375
11/32 0.343 750 8.731 250 27/32 0.843 750 21.431 250
23/64 0.359 375 9.128 125 55/64 0.859 375 21.828 125
3/8 0.375 000 9.525 000 7/8 0.875 000 22.225 000
25/64 0.390 625 9.921 875 57/64 0.890 625 22.621 875
13/32 0.406 250 10.318 750 29/32 0.906 250 23.018 750
27/64 0.421 875 10.715 625 59/64 0.921 875 23.415 625
7/16 0.437 500 11.112 500 15/16 0.937 500 23.812 500
29/64 0.453 125 11.509 375 61/64 0.953 125 24.209 375
15/32 0.468 750 11.906 250 31/32 0.968 750 24.606 250
31/64 0.484 375 12.303 125 63/64 0.984 375 25.003 125
1/2 0.500 000 12.700 000 1 1.000 000 25.400 000

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 AWS C5.3:2000

Annex B
Safety References
(This Annex is not a part of AWS C5.3:2000, Recommended Practices for Air Carbon Arc Gouging and Cutting, but
is included for information purposes only.)

The following references are listed by their source: Available through: American Welding Society, 550
N.W. LeJeune Road, Miami, FL 33126; Phone: 1-800-
(1) ACGIH, Threshold Limit Values for Chemical 334-9353
Substances and Physical Agents Biological Exposure Limits
(7) Code of Federal Regulations (OSHA), Section 29
Available through: ACGIH, 1330 Kemper Meadow Part 1910.95, 132, 133, 134, 139,251, 253, 254, and 1000
Drive, Cincinnati, OH 45240-1634; Phone: 513-742-2020
Available through: U.S. Government Printing Office,
(2) ANSI Z87.1, Practice for—Occupational and Edu- Superintendent of Documents, P.O. Box 371954, Pitts-
cational Eye and Face Protection burgh, PA 15250-7954; Phone: 202-512-1800
(3) ANSI Z88.2, Respiratory Protection
(8) CSA Standard W117.2, Safety in Welding, Cutting,
Available through: American National Standards In- and Allied Processes
stitute, 11 West 42nd Street, 13th Floor, New York, NY
10036-8002; Phone: 212-642-4900 Available through: CSA International, 178 Rexdale
Boulevard, Toronto, ON; Phone 800-463-6727
(4) ANSI Z49.1, Safety in Welding, Cutting, and Allied
Processes (9) NFPA 51B, Standard for Fire Prevention During
Welding, Cutting, and Other Hot Work
(5) AWS F4.1, Recommended Safe Practices for
Preparation for Welding and Cutting of Containers and Available through: National Fire Protection Associa-
Piping tion, 1 Batterymarch Park, P.O. Box 9101, Quincy, MA
(6) AWS Health and Safety Fact Sheets 02269-9101; Phone: 617-770-3000

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 AWS C5.3:2000

Annex C
Guidelines for Preparation of Technical Inquiries
for AWS Technical Committees
(This Annex is not a part of AWS C5.3:2000, Recommended Practices for Air Carbon Arc Gouging and Cutting, but
is included for information purposes only.)

C1. Introduction two or more interrelated provisions. That provision must

be identified in the scope of the inquiry, along with the
The AWS Board of Directors has adopted a policy edition of the standard that contains the provisions or that
whereby all official interpretations of AWS standards the inquirer is addressing.
will be handled in a formal manner. Under that policy, all
interpretations are made by the committee that is respon- C2.2 Purpose of the Inquiry. The purpose of the inquiry
sible for the standard. Official communication concern- must be stated in this portion of the inquiry. The purpose
ing an interpretation is through the AWS staff member can be either to obtain an interpretation of a standard
who works with that committee. The policy requires that requirement, or to request the revision of a particular pro-
all requests for an interpretation be submitted in writing. vision in the standard.
Such requests will be handled as expeditiously as possi- C2.3 Content of the Inquiry. The inquiry should be
ble but due to the complexity of the work and the proce- concise, yet complete, to enable the committee to quickly
dures that must be followed, some interpretations may and fully understand the point of the inquiry. Sketches
require considerable time. should be used when appropriate and all paragraphs, fig-
ures, and tables (or the Annex), which bear on the in-
quiry must be cited. If the point of the inquiry is to obtain
C2. Procedure a revision of the standard, the inquiry must provide tech-
nical justification for that revision.
All inquiries must be directed to:
C2.4 Proposed Reply. The inquirer should, as a pro-
Managing Director, Technical Services posed reply, state an interpretation of the provision that is
American Welding Society the point of the inquiry, or the wording for a proposed re-
550 N.W. LeJeune Road vision, if that is what inquirer seeks.
Miami, FL 33126
All inquiries must contain the name, address, and af-
filiation of the inquirer, and they must provide enough in- C3. Interpretation of Provisions of
formation for the committee to fully understand the point the Standard
of concern in the inquiry. Where that point is not clearly
Interpretations of provisions of the standard are made
defined, the inquiry will be returned for clarification. For
by the relevant AWS Technical Committee. The secre-
efficient handling, all inquiries should be typewritten and
tary of the committee refers all inquiries to the chairman
should also be in the format used here.
of the particular subcommittee that has jurisdiction over
C2.1 Scope. Each inquiry must address one single provi- the portion of the standard addressed by the inquiry. The
sion of the standard, unless the point of the inquiry involves subcommittee reviews the inquiry and the proposed reply

21
AWS C5.3:2000

to determine what the response to the inquiry should be. an official interpretation of any AWS standard with the
Following the subcommittee’s development of the re- information that such an interpretation can be obtained
sponse, the inquiry and the response are presented to the only through a written request. The Headquarters staff
entire committee for review and approval. Upon approval can not provide consulting services. The staff can, however,
by the committee, the interpretation will be an official in- refer a caller to any of those consultants whose names are
terpretation of the Society, and the secretary will transmit on file at AWS Headquarters.
the response to the inquirer and to the Welding Journal
for publication.
C6. The AWS Technical Committee
C4. Publication of Interpretations The activities of AWS Technical Committees in re-
gard to interpretations, are limited strictly to the Interpre-
All official interpretations will appear in the Welding
Journal. tation of provisions of standards prepared by the committee
or to consideration of revisions to existing provisions on
the basis of new data or technology. Neither the commit-
tee nor the staff is in a position to offer interpretive or
C5. Telephone Inquiries consulting services on: (1) specific engineering problems,
Telephone inquiries to AWS Headquarters concerning or (2) requirements of standards applied to fabrications
AWS standards should be limited to questions of a gen- outside the scope of the document or points not specifi-
eral nature or to matters directly related to the use of the cally covered by the standard. In such cases, the inquirer
Standard. The Board of Directors’ policy requires that all should seek assistance from a competent engineer expe-
AWS staff members respond to a telephone request for rienced in the particular field of interest.

22
 AWS C5.3:2000

AWS List of Documents on Arc Welding and Cutting

AWS Designation Title

C5.1 Recommended Practices for Plasma Arc Welding
C5.2 Recommended Practices for Plasma Arc Cutting
C5.3 Recommended Practices for Air Carbon Arc Gouging and Cutting
C5.4 Recommended Practices for Stud Welding
C5.5 Recommended Practices for Gas Tungsten Arc Welding
C5.6 Recommended Practices for Gas Metal Arc Welding
C5.7 Recommended Practices for Electrogas Welding
C5.10 Recommended Practices for Shielding Gases for Welding and Plasma Arc Cutting
For ordering information, contact the AWS Order Department, American Welding Society, 550 N.W. LeJeune Road,
Miami, FL 33126. Telephones: (800) 334-9353, (305) 443-9353, ext. 280; FAX (305) 443-7559.

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