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 a shielding gas supplied from an external source,
making it particularly suitable for production welding of carbon
steel?
A. Shielded Metal Arc Welding (SMAW)
B. Gas Metal Arc Welding (GMAW)
C. Gas Tungsten Arc Welding (GTAW)
D. Oxyfuel Welding (OFW)
B. Gas Metal Arc Welding (GMAW)
GMAW uses a continuously fed consumable wire electrode together with
externally supplied shielding gas. Its continuous wire feed makes it
efficient for production and fabrication work.
2. What is the primary purpose of shielding gas during an arc-welding
operation?
A. To increase the electrical resistance of the electrode
B. To cool the weld pool immediately
,C. To protect the molten weld metal from atmospheric contamination
D. To increase the hardness of the base metal
C. To protect the molten weld metal from atmospheric contamination
Shielding gas prevents oxygen, nitrogen, and other atmospheric
contaminants from reacting with the molten weld pool. Proper shielding
is essential for preventing porosity, oxidation, and other weld defects.
3. Which welding process uses a nonconsumable tungsten electrode
and is commonly selected when precise control and high-quality
welds are required?
A. GTAW
B. FCAW
C. GMAW
D. SMAW
A. GTAW
Gas Tungsten Arc Welding uses a nonconsumable tungsten electrode
and provides excellent control of the arc and weld pool. It is commonly
used where weld quality and precision are especially important.
4. What is the principal function of flux in shielded metal arc welding?
A. To increase the diameter of the electrode
B. To provide shielding and assist in removing impurities from the weld
C. To eliminate the need for an electrical circuit
D. To prevent the electrode from melting
B. To provide shielding and assist in removing impurities from the weld
,The electrode coating produces gases and slag that protect the molten
metal and help remove contaminants. The resulting slag must normally
be removed after welding.
5. Which electrode classification is commonly associated with an
E7018 low-hydrogen SMAW electrode?
A. Cellulosic electrode intended only for cutting
B. Low-hydrogen electrode used for structural-quality welding
C. Tungsten electrode used for GTAW
D. Bare aluminum electrode used for brazing
B. Low-hydrogen electrode used for structural-quality welding
E7018 is a low-hydrogen, iron-powder electrode widely used for
structural welding. The designation indicates important characteristics
including minimum tensile strength and welding position.
6. In the AWS electrode designation E7018, what does the number
“70” primarily indicate?
A. The electrode diameter in thousandths of an inch
B. The minimum tensile strength in thousands of pounds per square inch
C. The maximum welding current
D. The minimum preheat temperature
B. The minimum tensile strength in thousands of pounds per square inch
The “70” indicates a minimum tensile strength of approximately 70 ksi
for the deposited weld metal. The remaining digits provide information
about welding position and coating/current characteristics.
, 7. Why are low-hydrogen electrodes such as E7018 commonly stored
in controlled conditions?
A. To prevent excessive electrode melting
B. To prevent absorption of atmospheric moisture
C. To increase the electrode diameter
D. To make the coating electrically nonconductive
B. To prevent absorption of atmospheric moisture
Moisture can introduce hydrogen into the weld, increasing the risk of
hydrogen-induced cracking. Low-hydrogen electrodes therefore require
proper storage and handling according to applicable requirements.
8. What is the most appropriate action when the coating on a low-
hydrogen electrode has become damaged or contaminated?
A. Use it immediately at maximum amperage
B. Dip it in water before welding
C. Follow the applicable electrode storage and reconditioning
requirements or discard it
D. Remove all remaining coating and use the bare rod
C. Follow the applicable electrode storage and reconditioning
requirements or discard it
Damaged or moisture-contaminated electrode coatings can compromise
weld quality and increase cracking risk. Electrodes should be handled
according to the manufacturer's and applicable code requirements.
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 a shielding gas supplied from an external source,
making it particularly suitable for production welding of carbon
steel?
A. Shielded Metal Arc Welding (SMAW)
B. Gas Metal Arc Welding (GMAW)
C. Gas Tungsten Arc Welding (GTAW)
D. Oxyfuel Welding (OFW)
B. Gas Metal Arc Welding (GMAW)
GMAW uses a continuously fed consumable wire electrode together with
externally supplied shielding gas. Its continuous wire feed makes it
efficient for production and fabrication work.
2. What is the primary purpose of shielding gas during an arc-welding
operation?
A. To increase the electrical resistance of the electrode
B. To cool the weld pool immediately
,C. To protect the molten weld metal from atmospheric contamination
D. To increase the hardness of the base metal
C. To protect the molten weld metal from atmospheric contamination
Shielding gas prevents oxygen, nitrogen, and other atmospheric
contaminants from reacting with the molten weld pool. Proper shielding
is essential for preventing porosity, oxidation, and other weld defects.
3. Which welding process uses a nonconsumable tungsten electrode
and is commonly selected when precise control and high-quality
welds are required?
A. GTAW
B. FCAW
C. GMAW
D. SMAW
A. GTAW
Gas Tungsten Arc Welding uses a nonconsumable tungsten electrode
and provides excellent control of the arc and weld pool. It is commonly
used where weld quality and precision are especially important.
4. What is the principal function of flux in shielded metal arc welding?
A. To increase the diameter of the electrode
B. To provide shielding and assist in removing impurities from the weld
C. To eliminate the need for an electrical circuit
D. To prevent the electrode from melting
B. To provide shielding and assist in removing impurities from the weld
,The electrode coating produces gases and slag that protect the molten
metal and help remove contaminants. The resulting slag must normally
be removed after welding.
5. Which electrode classification is commonly associated with an
E7018 low-hydrogen SMAW electrode?
A. Cellulosic electrode intended only for cutting
B. Low-hydrogen electrode used for structural-quality welding
C. Tungsten electrode used for GTAW
D. Bare aluminum electrode used for brazing
B. Low-hydrogen electrode used for structural-quality welding
E7018 is a low-hydrogen, iron-powder electrode widely used for
structural welding. The designation indicates important characteristics
including minimum tensile strength and welding position.
6. In the AWS electrode designation E7018, what does the number
“70” primarily indicate?
A. The electrode diameter in thousandths of an inch
B. The minimum tensile strength in thousands of pounds per square inch
C. The maximum welding current
D. The minimum preheat temperature
B. The minimum tensile strength in thousands of pounds per square inch
The “70” indicates a minimum tensile strength of approximately 70 ksi
for the deposited weld metal. The remaining digits provide information
about welding position and coating/current characteristics.
, 7. Why are low-hydrogen electrodes such as E7018 commonly stored
in controlled conditions?
A. To prevent excessive electrode melting
B. To prevent absorption of atmospheric moisture
C. To increase the electrode diameter
D. To make the coating electrically nonconductive
B. To prevent absorption of atmospheric moisture
Moisture can introduce hydrogen into the weld, increasing the risk of
hydrogen-induced cracking. Low-hydrogen electrodes therefore require
proper storage and handling according to applicable requirements.
8. What is the most appropriate action when the coating on a low-
hydrogen electrode has become damaged or contaminated?
A. Use it immediately at maximum amperage
B. Dip it in water before welding
C. Follow the applicable electrode storage and reconditioning
requirements or discard it
D. Remove all remaining coating and use the bare rod
C. Follow the applicable electrode storage and reconditioning
requirements or discard it
Damaged or moisture-contaminated electrode coatings can compromise
weld quality and increase cracking risk. Electrodes should be handled
according to the manufacturer's and applicable code requirements.
