UA STAR Pipefitter Certification Practice
Examination 2026–2027 | Comprehensive
200-Question Practice Test with Answers
& Rationales| Free Pdf Access.
Question 1: What is the primary purpose of an isometric drawing in pipefitting?
A) To show electrical wiring diagrams
B) To provide a three-dimensional view of the piping system for fabrication and
installation
C) To calculate fluid pressure drop
D) To list material quantities for ordering
Answer: B
Isometric drawings are essential because they present a three-dimensional representation
of the piping layout. This allows pipefitters to visualize how pipes are routed through
space, where fittings and valves are placed, and how different components connect to each
other. This visualization is critical for accurate fabrication, assembly, and installation in
the field. Options A, C, and D describe other types of documents or calculations that are
not the primary function of an isometric drawing.
Question 2: What is the most common welding process used for carbon steel
piping in the field?
,A) Gas Tungsten Arc Welding (GTAW)
B) Shielded Metal Arc Welding (SMAW)
C) Flux-Cored Arc Welding (FCAW)
D) Oxy-Fuel Welding
Answer: B
Shielded Metal Arc Welding, commonly known as stick welding, is the most frequently
used process for carbon steel piping in field conditions. Its popularity stems from its
portability, as the equipment is relatively simple and does not require external shielding
gas. The electrodes used in SMAW also provide excellent penetration and strong welds,
which are essential for pressure piping systems. While GTAW is used for high-purity or
thin-wall applications and FCAW is common in shop settings, SMAW remains the field
standard for carbon steel.
Question 3: In pipefitting, what does "NPS" stand for?
A) National Pipe Standard
B) Nominal Pipe Size
C) Normal Pressure Schedule
D) Non-Pressure Steel
Answer: B
NPS stands for Nominal Pipe Size, which is a North American standard for identifying pipe
dimensions. It is important to understand that NPS is a dimensionless number and does
not directly correspond to the actual measured outside or inside diameter of the pipe. For
example, a 4-inch NPS pipe does not measure exactly 4 inches in diameter. This standard
helps ensure consistency across different manufacturers and allows for proper matching of
fittings and flanges.
,Question 4: The wall thickness of a pipe is commonly referred to by its:
A) NPS number
B) Schedule number
C) DN number
D) Weight class
Answer: B
The schedule number is the standard designation for pipe wall thickness. Common
examples include Schedule 40, Schedule 80, and Schedule 160. For a given NPS, a higher
schedule number indicates a thicker wall, which means the pipe can withstand higher
internal pressures but also has a smaller inside diameter. This is critical information when
selecting pipe for specific pressure and temperature applications, as the wall thickness
directly affects the pipe's strength and flow capacity.
Question 5: A line labeled “3”-150#-CW-CS” indicates what type of pipe?
A) 3-inch copper water pipe, Class 150
B) 3-inch cast iron pipe for sanitary waste
C) 3-inch carbon steel pipe, Class 150, carrying chilled water
D) 3-inch concrete sewer pipe
Answer: C
This labeling system is commonly used on engineering drawings and pipe specifications.
The "3"" refers to the nominal pipe size of 3 inches. The "150#" indicates the pressure
rating, which is Class 150, meaning the pipe and fittings are designed for a maximum
working pressure of approximately 150 psi at ambient temperature. "CW" stands for
Chilled Water, which is the service or fluid being transported. "CS" stands for Carbon Steel,
, which is the material of construction. Options A, B, and D incorrectly identify the material
or the service fluid.
Question 6: Which of the following valves provides precise throttling of flow?
A) Gate valve
B) Globe valve
C) Check valve
D) Ball valve
Answer: B
Globe valves are specifically designed for throttling and regulating flow. Their internal
design features a disk and seat configuration that allows for fine control of the flow rate by
adjusting the valve stem position. Gate valves are designed to be either fully open or fully
closed and are not suitable for throttling because they can be damaged by flow erosion.
Check valves are automatic valves that prevent backflow and do not provide throttling.
Ball valves are typically used for on-off service, although some specialized designs may
offer limited throttling capabilities.
Question 7: What is the purpose of a strainer in a piping system?
A) To regulate the temperature of the fluid
B) To remove debris and contaminants from the flow stream
C) To increase the flow rate through the pipe
D) To reduce pipe vibration and noise
Answer: B
A strainer is installed in a piping system specifically to capture and remove debris, scale,
Examination 2026–2027 | Comprehensive
200-Question Practice Test with Answers
& Rationales| Free Pdf Access.
Question 1: What is the primary purpose of an isometric drawing in pipefitting?
A) To show electrical wiring diagrams
B) To provide a three-dimensional view of the piping system for fabrication and
installation
C) To calculate fluid pressure drop
D) To list material quantities for ordering
Answer: B
Isometric drawings are essential because they present a three-dimensional representation
of the piping layout. This allows pipefitters to visualize how pipes are routed through
space, where fittings and valves are placed, and how different components connect to each
other. This visualization is critical for accurate fabrication, assembly, and installation in
the field. Options A, C, and D describe other types of documents or calculations that are
not the primary function of an isometric drawing.
Question 2: What is the most common welding process used for carbon steel
piping in the field?
,A) Gas Tungsten Arc Welding (GTAW)
B) Shielded Metal Arc Welding (SMAW)
C) Flux-Cored Arc Welding (FCAW)
D) Oxy-Fuel Welding
Answer: B
Shielded Metal Arc Welding, commonly known as stick welding, is the most frequently
used process for carbon steel piping in field conditions. Its popularity stems from its
portability, as the equipment is relatively simple and does not require external shielding
gas. The electrodes used in SMAW also provide excellent penetration and strong welds,
which are essential for pressure piping systems. While GTAW is used for high-purity or
thin-wall applications and FCAW is common in shop settings, SMAW remains the field
standard for carbon steel.
Question 3: In pipefitting, what does "NPS" stand for?
A) National Pipe Standard
B) Nominal Pipe Size
C) Normal Pressure Schedule
D) Non-Pressure Steel
Answer: B
NPS stands for Nominal Pipe Size, which is a North American standard for identifying pipe
dimensions. It is important to understand that NPS is a dimensionless number and does
not directly correspond to the actual measured outside or inside diameter of the pipe. For
example, a 4-inch NPS pipe does not measure exactly 4 inches in diameter. This standard
helps ensure consistency across different manufacturers and allows for proper matching of
fittings and flanges.
,Question 4: The wall thickness of a pipe is commonly referred to by its:
A) NPS number
B) Schedule number
C) DN number
D) Weight class
Answer: B
The schedule number is the standard designation for pipe wall thickness. Common
examples include Schedule 40, Schedule 80, and Schedule 160. For a given NPS, a higher
schedule number indicates a thicker wall, which means the pipe can withstand higher
internal pressures but also has a smaller inside diameter. This is critical information when
selecting pipe for specific pressure and temperature applications, as the wall thickness
directly affects the pipe's strength and flow capacity.
Question 5: A line labeled “3”-150#-CW-CS” indicates what type of pipe?
A) 3-inch copper water pipe, Class 150
B) 3-inch cast iron pipe for sanitary waste
C) 3-inch carbon steel pipe, Class 150, carrying chilled water
D) 3-inch concrete sewer pipe
Answer: C
This labeling system is commonly used on engineering drawings and pipe specifications.
The "3"" refers to the nominal pipe size of 3 inches. The "150#" indicates the pressure
rating, which is Class 150, meaning the pipe and fittings are designed for a maximum
working pressure of approximately 150 psi at ambient temperature. "CW" stands for
Chilled Water, which is the service or fluid being transported. "CS" stands for Carbon Steel,
, which is the material of construction. Options A, B, and D incorrectly identify the material
or the service fluid.
Question 6: Which of the following valves provides precise throttling of flow?
A) Gate valve
B) Globe valve
C) Check valve
D) Ball valve
Answer: B
Globe valves are specifically designed for throttling and regulating flow. Their internal
design features a disk and seat configuration that allows for fine control of the flow rate by
adjusting the valve stem position. Gate valves are designed to be either fully open or fully
closed and are not suitable for throttling because they can be damaged by flow erosion.
Check valves are automatic valves that prevent backflow and do not provide throttling.
Ball valves are typically used for on-off service, although some specialized designs may
offer limited throttling capabilities.
Question 7: What is the purpose of a strainer in a piping system?
A) To regulate the temperature of the fluid
B) To remove debris and contaminants from the flow stream
C) To increase the flow rate through the pipe
D) To reduce pipe vibration and noise
Answer: B
A strainer is installed in a piping system specifically to capture and remove debris, scale,
