CO Welding Contractor Exam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf.
1. Which welding process uses a continuously fed consumable wire
electrode and an externally supplied shielding gas to establish an
arc between the wire and the workpiece?
A. Shielded metal arc welding (SMAW)
B. Gas tungsten arc welding (GTAW)
C. Gas metal arc welding (GMAW)
D. Oxyfuel gas welding (OFW)
GMAW uses a continuously fed consumable wire electrode while
shielding gas protects the molten weld pool from atmospheric
contamination.
2. Which welding process uses a nonconsumable tungsten electrode
and may use either an inert shielding gas or a helium/argon
mixture?
A. Flux-cored arc welding
B. Gas tungsten arc welding (GTAW)
C. Submerged arc welding
D. Shielded metal arc welding
,GTAW, commonly called TIG welding, uses a nonconsumable tungsten
electrode and shielding gas to produce highly controlled welds.
3. What is the primary purpose of shielding gas during arc welding?
A. Increase the electrical resistance of the electrode
B. Cool the welding machine
C. Increase the melting temperature of steel
D. Prevent atmospheric gases from contaminating the molten weld pool
Shielding gas protects molten metal from oxygen, nitrogen, and other
atmospheric contaminants that can cause porosity, embrittlement, and
other weld defects.
4. In shielded metal arc welding, what provides shielding for the
molten weld pool?
A. Compressed air
B. Argon supplied through a regulator
C. The flux coating on the electrode
D. Water cooling
The SMAW electrode coating decomposes and produces shielding gases
and slag that protect the weld metal during solidification.
5. Which welding process is generally identified by the use of a flux-
coated, consumable electrode that is manually fed into the weld?
A. GTAW
B. GMAW
,C. SMAW
D. Resistance welding
SMAW uses individual flux-coated electrodes that are consumed as the
arc melts the electrode and base metal.
6. What is the principal purpose of welding preheat on many carbon-
steel applications?
A. Eliminate the need for shielding gas
B. Reduce the cooling rate and lower the risk of hydrogen cracking
C. Increase electrode consumption
D. Make the weld bead freeze immediately
Preheating reduces the temperature difference between the weld area
and surrounding metal, slowing cooling and helping reduce cracking
risks, particularly hydrogen-assisted cracking.
7. What condition most directly contributes to hydrogen-induced
cracking in susceptible steels?
A. Excessive argon flow alone
B. Low electrical resistance in the welding cable
C. Hydrogen contamination combined with a susceptible microstructure
and tensile stress
D. Excessive weld visibility
Hydrogen cracking requires a combination of diffusible hydrogen, a
susceptible microstructure, and tensile stress, commonly occurring after
the weld cools.
, 8. Why are low-hydrogen SMAW electrodes commonly stored in
controlled conditions?
A. To increase their flux moisture
B. To prevent the electrode from becoming magnetic
C. To prevent moisture absorption that can introduce hydrogen into the
weld
D. To increase the electrode diameter
Low-hydrogen electrodes must be protected from moisture because
absorbed water can contribute hydrogen to the welding arc and
increase cracking susceptibility.
9. Which electrode classification is commonly associated with an
SMAW electrode having a minimum tensile strength of
approximately 70 ksi?
A. E6010
B. E6013
C. E7018
D. E308L
The first two or three digits in an AWS SMAW electrode classification
indicate important mechanical characteristics; E7018 is commonly
classified at 70 ksi minimum tensile strength.
10. What does the “18” in an E7018 electrode classification
primarily identify?
Questions And Correct Answers
(Verified Answers) Plus Rationale 2027
Q&A| Instant Download Pdf.
1. Which welding process uses a continuously fed consumable wire
electrode and an externally supplied shielding gas to establish an
arc between the wire and the workpiece?
A. Shielded metal arc welding (SMAW)
B. Gas tungsten arc welding (GTAW)
C. Gas metal arc welding (GMAW)
D. Oxyfuel gas welding (OFW)
GMAW uses a continuously fed consumable wire electrode while
shielding gas protects the molten weld pool from atmospheric
contamination.
2. Which welding process uses a nonconsumable tungsten electrode
and may use either an inert shielding gas or a helium/argon
mixture?
A. Flux-cored arc welding
B. Gas tungsten arc welding (GTAW)
C. Submerged arc welding
D. Shielded metal arc welding
,GTAW, commonly called TIG welding, uses a nonconsumable tungsten
electrode and shielding gas to produce highly controlled welds.
3. What is the primary purpose of shielding gas during arc welding?
A. Increase the electrical resistance of the electrode
B. Cool the welding machine
C. Increase the melting temperature of steel
D. Prevent atmospheric gases from contaminating the molten weld pool
Shielding gas protects molten metal from oxygen, nitrogen, and other
atmospheric contaminants that can cause porosity, embrittlement, and
other weld defects.
4. In shielded metal arc welding, what provides shielding for the
molten weld pool?
A. Compressed air
B. Argon supplied through a regulator
C. The flux coating on the electrode
D. Water cooling
The SMAW electrode coating decomposes and produces shielding gases
and slag that protect the weld metal during solidification.
5. Which welding process is generally identified by the use of a flux-
coated, consumable electrode that is manually fed into the weld?
A. GTAW
B. GMAW
,C. SMAW
D. Resistance welding
SMAW uses individual flux-coated electrodes that are consumed as the
arc melts the electrode and base metal.
6. What is the principal purpose of welding preheat on many carbon-
steel applications?
A. Eliminate the need for shielding gas
B. Reduce the cooling rate and lower the risk of hydrogen cracking
C. Increase electrode consumption
D. Make the weld bead freeze immediately
Preheating reduces the temperature difference between the weld area
and surrounding metal, slowing cooling and helping reduce cracking
risks, particularly hydrogen-assisted cracking.
7. What condition most directly contributes to hydrogen-induced
cracking in susceptible steels?
A. Excessive argon flow alone
B. Low electrical resistance in the welding cable
C. Hydrogen contamination combined with a susceptible microstructure
and tensile stress
D. Excessive weld visibility
Hydrogen cracking requires a combination of diffusible hydrogen, a
susceptible microstructure, and tensile stress, commonly occurring after
the weld cools.
, 8. Why are low-hydrogen SMAW electrodes commonly stored in
controlled conditions?
A. To increase their flux moisture
B. To prevent the electrode from becoming magnetic
C. To prevent moisture absorption that can introduce hydrogen into the
weld
D. To increase the electrode diameter
Low-hydrogen electrodes must be protected from moisture because
absorbed water can contribute hydrogen to the welding arc and
increase cracking susceptibility.
9. Which electrode classification is commonly associated with an
SMAW electrode having a minimum tensile strength of
approximately 70 ksi?
A. E6010
B. E6013
C. E7018
D. E308L
The first two or three digits in an AWS SMAW electrode classification
indicate important mechanical characteristics; E7018 is commonly
classified at 70 ksi minimum tensile strength.
10. What does the “18” in an E7018 electrode classification
primarily identify?
