Page 1 of 129
PIPEFITTER STAR EXAM 2026|REAL
800Qs&As|A+GRADE|NEW UPDATE
1. In pipefitting, what does NPS stand for?
A) Nominal Pipe Size
B) National Pipe Standard
C) Normal Pipe Schedule
D) Non-Pressure Steel
Answer: A – Nominal Pipe Size.
Rationale: NPS is a North American standard set of sizes for
pipes used for high or low pressures and temperatures. It is
based on a dimensionless number (e.g., NPS 4 is 4 inches
nominal, but actual outside diameter is 4.5 inches).
2. The wall thickness of a pipe is commonly referred to by its:
A) NPS number
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B) Schedule (SCH) number
C) DN number
D) Weight class
Answer: B – Schedule (SCH) number.
Rationale: Schedule indicates the wall thickness; higher schedule
numbers correspond to thicker walls for a given NPS (e.g., SCH
40, SCH 80, SCH 160).
3. Which of the following is NOT a standard pipe fitting?
A) 90° elbow (LR or SR)
B) Tee
C) Cross
D) Gearbox
Answer: D – Gearbox is a mechanical component, not a pipe
fitting.
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Rationale: Standard pipe fittings include elbows, tees, reducers,
caps, crosses, couplings, and unions.
4. A “long radius” (LR) 90° elbow has a center-to-end
dimension equal to _____ times the nominal pipe size.
A) 1.0
B) 1.5
C) 2.0
D) 2.5
Answer: B – 1.5 × NPS.
Rationale: Short radius (SR) 90° elbow has center-to-end = 1.0 ×
NPS. Long radius elbows provide lower pressure drop and are
preferred for most applications.
5. The difference between a “concentric reducer” and an
“eccentric reducer” is:
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A) Concentric reduces diameter on the same centerline; eccentric
reduces offset to maintain a flat bottom.
B) Eccentric is used only for vertical lines.
C) Concentric has a flat bottom; eccentric has a sloped bottom.
D) No difference.
Answer: A – Concentric reducers are symmetrical; eccentric
reducers have an offset centerline, typically used to keep the
bottom of the pipe level (e.g., pump suction lines).
Rationale: Eccentric reducers prevent air pockets in horizontal
lines.
6. What is the primary purpose of a “union” in a piping
system?
A) To change direction of flow
B) To allow easy disconnection for maintenance
PIPEFITTER STAR EXAM 2026|REAL
800Qs&As|A+GRADE|NEW UPDATE
1. In pipefitting, what does NPS stand for?
A) Nominal Pipe Size
B) National Pipe Standard
C) Normal Pipe Schedule
D) Non-Pressure Steel
Answer: A – Nominal Pipe Size.
Rationale: NPS is a North American standard set of sizes for
pipes used for high or low pressures and temperatures. It is
based on a dimensionless number (e.g., NPS 4 is 4 inches
nominal, but actual outside diameter is 4.5 inches).
2. The wall thickness of a pipe is commonly referred to by its:
A) NPS number
,Page 2 of 129
B) Schedule (SCH) number
C) DN number
D) Weight class
Answer: B – Schedule (SCH) number.
Rationale: Schedule indicates the wall thickness; higher schedule
numbers correspond to thicker walls for a given NPS (e.g., SCH
40, SCH 80, SCH 160).
3. Which of the following is NOT a standard pipe fitting?
A) 90° elbow (LR or SR)
B) Tee
C) Cross
D) Gearbox
Answer: D – Gearbox is a mechanical component, not a pipe
fitting.
,Page 3 of 129
Rationale: Standard pipe fittings include elbows, tees, reducers,
caps, crosses, couplings, and unions.
4. A “long radius” (LR) 90° elbow has a center-to-end
dimension equal to _____ times the nominal pipe size.
A) 1.0
B) 1.5
C) 2.0
D) 2.5
Answer: B – 1.5 × NPS.
Rationale: Short radius (SR) 90° elbow has center-to-end = 1.0 ×
NPS. Long radius elbows provide lower pressure drop and are
preferred for most applications.
5. The difference between a “concentric reducer” and an
“eccentric reducer” is:
, Page 4 of 129
A) Concentric reduces diameter on the same centerline; eccentric
reduces offset to maintain a flat bottom.
B) Eccentric is used only for vertical lines.
C) Concentric has a flat bottom; eccentric has a sloped bottom.
D) No difference.
Answer: A – Concentric reducers are symmetrical; eccentric
reducers have an offset centerline, typically used to keep the
bottom of the pipe level (e.g., pump suction lines).
Rationale: Eccentric reducers prevent air pockets in horizontal
lines.
6. What is the primary purpose of a “union” in a piping
system?
A) To change direction of flow
B) To allow easy disconnection for maintenance
