AR CA C-43 Sheet Metal Contractor Exam
Questions and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant Download Pdf
1. Which property of galvanized steel helps protect the underlying steel
from corrosion?
A. Chromium plating
B. Zinc coating
C. Copper cladding
D. Tin soldering
Rationale: Galvanized steel is coated with zinc, which provides a
protective barrier against moisture and corrosion. Zinc also offers
sacrificial protection because it corrodes preferentially to the underlying
steel when the coating is damaged.
2. What is the primary purpose of a Pittsburgh lock seam in sheet metal
duct fabrication?
A. To provide thermal insulation
,B. To increase airflow velocity
C. To mechanically join sheet metal edges
D. To eliminate the need for duct supports
Rationale: A Pittsburgh lock seam mechanically interlocks folded sheet
metal edges to create a continuous joint. It is commonly used in
rectangular ductwork because it provides structural integrity and can be
sealed when required.
3. Which instrument is most appropriate for measuring the thickness of
sheet metal accurately?
A. Tape measure
B. Framing square
C. Sheet metal thickness gauge
D. Spirit level
Rationale: A sheet metal thickness gauge is designed to determine the
thickness of metal stock. Accurate thickness measurement helps ensure
that the selected material meets fabrication specifications and
structural requirements.
4. What does the term “gauge” generally indicate in conventional sheet
metal sizing?
,A. The length of the sheet
B. The width of the sheet
C. The thickness of the sheet
D. The weight of the duct insulation
Rationale: Sheet metal gauge is a conventional designation for material
thickness. In many commonly used gauge systems, a higher gauge
number corresponds to thinner material, although the actual thickness
depends on the material and gauge standard.
5. Which metal is commonly used for corrosion-resistant sheet metal
applications involving moisture?
A. Uncoated carbon steel
B. Stainless steel
C. Unprotected cast iron
D. Plain carbon tool steel
Rationale: Stainless steel contains chromium, which forms a passive
oxide layer that helps resist corrosion. The appropriate stainless steel
grade must still be selected based on the specific moisture, chemical
exposure, temperature, and service conditions.
6. What is the main purpose of a sheet metal shear?
, A. To bend metal into a channel
B. To punch holes in concrete
C. To cut sheet metal along a straight line
D. To apply insulation adhesive
Rationale: A sheet metal shear uses opposing cutting edges to separate
sheet material. It is commonly used for straight cuts during duct
fabrication, and its capacity must be appropriate for the material type
and thickness.
7. Which tool is commonly used to mark a straight cutting line on sheet
metal?
A. Pipe wrench
B. Steel rule and scriber
C. Plumb bob
D. Torque wrench
Rationale: A steel rule provides a straight measurement reference, while
a scriber creates a visible line on the metal surface. Accurate marking
helps reduce cutting errors and material waste.
8. What is the purpose of a hand seamer?
A. To measure duct static pressure
Questions and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant Download Pdf
1. Which property of galvanized steel helps protect the underlying steel
from corrosion?
A. Chromium plating
B. Zinc coating
C. Copper cladding
D. Tin soldering
Rationale: Galvanized steel is coated with zinc, which provides a
protective barrier against moisture and corrosion. Zinc also offers
sacrificial protection because it corrodes preferentially to the underlying
steel when the coating is damaged.
2. What is the primary purpose of a Pittsburgh lock seam in sheet metal
duct fabrication?
A. To provide thermal insulation
,B. To increase airflow velocity
C. To mechanically join sheet metal edges
D. To eliminate the need for duct supports
Rationale: A Pittsburgh lock seam mechanically interlocks folded sheet
metal edges to create a continuous joint. It is commonly used in
rectangular ductwork because it provides structural integrity and can be
sealed when required.
3. Which instrument is most appropriate for measuring the thickness of
sheet metal accurately?
A. Tape measure
B. Framing square
C. Sheet metal thickness gauge
D. Spirit level
Rationale: A sheet metal thickness gauge is designed to determine the
thickness of metal stock. Accurate thickness measurement helps ensure
that the selected material meets fabrication specifications and
structural requirements.
4. What does the term “gauge” generally indicate in conventional sheet
metal sizing?
,A. The length of the sheet
B. The width of the sheet
C. The thickness of the sheet
D. The weight of the duct insulation
Rationale: Sheet metal gauge is a conventional designation for material
thickness. In many commonly used gauge systems, a higher gauge
number corresponds to thinner material, although the actual thickness
depends on the material and gauge standard.
5. Which metal is commonly used for corrosion-resistant sheet metal
applications involving moisture?
A. Uncoated carbon steel
B. Stainless steel
C. Unprotected cast iron
D. Plain carbon tool steel
Rationale: Stainless steel contains chromium, which forms a passive
oxide layer that helps resist corrosion. The appropriate stainless steel
grade must still be selected based on the specific moisture, chemical
exposure, temperature, and service conditions.
6. What is the main purpose of a sheet metal shear?
, A. To bend metal into a channel
B. To punch holes in concrete
C. To cut sheet metal along a straight line
D. To apply insulation adhesive
Rationale: A sheet metal shear uses opposing cutting edges to separate
sheet material. It is commonly used for straight cuts during duct
fabrication, and its capacity must be appropriate for the material type
and thickness.
7. Which tool is commonly used to mark a straight cutting line on sheet
metal?
A. Pipe wrench
B. Steel rule and scriber
C. Plumb bob
D. Torque wrench
Rationale: A steel rule provides a straight measurement reference, while
a scriber creates a visible line on the metal surface. Accurate marking
helps reduce cutting errors and material waste.
8. What is the purpose of a hand seamer?
A. To measure duct static pressure
