AR SH Sheet Metal Contractor Exam
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
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Section 1: Sheet Metal Materials and Properties
Question 1
Which property of galvanized steel provides its primary protection
against corrosion?
A. A layer of chromium
B. A zinc coating
C. A copper coating
D. A layer of carbon
Correct Answer: B. A zinc coating
,Rationale: Galvanized steel is coated with zinc to protect the
underlying steel from corrosion. The zinc acts as a barrier against
moisture and oxygen and also provides sacrificial protection, meaning
the zinc corrodes preferentially to the steel when the coating is
damaged.
Question 2
Which sheet metal material is commonly used for HVAC ductwork
because of its strength, availability, and relatively low cost?
A. Lead sheet
B. Galvanized steel
C. Cast iron
D. Brass plate
Rationale: Galvanized steel is widely used in HVAC duct fabrication
because it offers good structural strength, corrosion resistance, and
ease of fabrication. Its zinc coating helps protect the steel from rust
during normal service conditions.
Question 3
What is the primary purpose of a Pittsburgh lock seam in sheet metal
fabrication?
,A. To create a permanent electrical ground
B. To increase the melting temperature of the metal
C. To join sheet metal edges mechanically
D. To eliminate the need for duct supports
Rationale: A Pittsburgh lock seam is a mechanical seam used to join
sheet metal edges, especially in rectangular ductwork. It forms an
interlocking connection that provides structural integrity and can be
sealed when required to meet duct leakage specifications.
Question 4
Which instrument is commonly used to measure the thickness of sheet
metal?
A. Anemometer
B. Hygrometer
C. Manometer
D. Sheet metal gauge or micrometer
Rationale: Sheet metal thickness can be measured with a micrometer
or an appropriate sheet metal gauge. A micrometer provides a direct
thickness measurement, while a gauge number identifies a
, standardized thickness that varies according to the material and
gauge system.
Question 5
What does the term “duct gauge” generally refer to?
A. The air velocity inside a duct
B. The thickness of the sheet metal
C. The duct's operating temperature
D. The amount of insulation installed
Rationale: Duct gauge identifies the thickness of the sheet metal used
to fabricate the duct. The required gauge depends on factors such as
duct dimensions, pressure classification, reinforcement, material, and
applicable construction standards.
Question 6
Which material is particularly suitable for sheet metal components
requiring good corrosion resistance in many outdoor environments?
A. Uncoated carbon steel
B. Plain black iron
C. Stainless steel
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
Section 1: Sheet Metal Materials and Properties
Question 1
Which property of galvanized steel provides its primary protection
against corrosion?
A. A layer of chromium
B. A zinc coating
C. A copper coating
D. A layer of carbon
Correct Answer: B. A zinc coating
,Rationale: Galvanized steel is coated with zinc to protect the
underlying steel from corrosion. The zinc acts as a barrier against
moisture and oxygen and also provides sacrificial protection, meaning
the zinc corrodes preferentially to the steel when the coating is
damaged.
Question 2
Which sheet metal material is commonly used for HVAC ductwork
because of its strength, availability, and relatively low cost?
A. Lead sheet
B. Galvanized steel
C. Cast iron
D. Brass plate
Rationale: Galvanized steel is widely used in HVAC duct fabrication
because it offers good structural strength, corrosion resistance, and
ease of fabrication. Its zinc coating helps protect the steel from rust
during normal service conditions.
Question 3
What is the primary purpose of a Pittsburgh lock seam in sheet metal
fabrication?
,A. To create a permanent electrical ground
B. To increase the melting temperature of the metal
C. To join sheet metal edges mechanically
D. To eliminate the need for duct supports
Rationale: A Pittsburgh lock seam is a mechanical seam used to join
sheet metal edges, especially in rectangular ductwork. It forms an
interlocking connection that provides structural integrity and can be
sealed when required to meet duct leakage specifications.
Question 4
Which instrument is commonly used to measure the thickness of sheet
metal?
A. Anemometer
B. Hygrometer
C. Manometer
D. Sheet metal gauge or micrometer
Rationale: Sheet metal thickness can be measured with a micrometer
or an appropriate sheet metal gauge. A micrometer provides a direct
thickness measurement, while a gauge number identifies a
, standardized thickness that varies according to the material and
gauge system.
Question 5
What does the term “duct gauge” generally refer to?
A. The air velocity inside a duct
B. The thickness of the sheet metal
C. The duct's operating temperature
D. The amount of insulation installed
Rationale: Duct gauge identifies the thickness of the sheet metal used
to fabricate the duct. The required gauge depends on factors such as
duct dimensions, pressure classification, reinforcement, material, and
applicable construction standards.
Question 6
Which material is particularly suitable for sheet metal components
requiring good corrosion resistance in many outdoor environments?
A. Uncoated carbon steel
B. Plain black iron
C. Stainless steel
