(NEWEST 2026) PIPE SIZING TEST QUESTIONS AND
VERIFIED ANSWERS PASS GUARANTEE
1. What are the three different categories used to identify pipe size?
Pipe is identified by Nominal Pipe Size (NPS), Outside Diameter (OD), and
Inside Diameter (ID).
2. How is Nominal Pipe Size (NPS) defined in process piping?
NPS identifies a pipe by name only. Much like a "2x4" piece of lumber, the
name refers to the pipe's identity rather than its exact measurement.
3. What do the terms Outside Diameter (OD) and Inside Diameter (ID)
represent?
OD and ID refer to the actual physical measurements of the pipe's exterior and
interior, respectively.
4. How does the NPS relate to the OD for pipes sized between 1/8" and 12"?
For pipes in this range, the actual outside diameter is greater than the nominal
pipe size ($OD > NPS$).
5. How does the NPS relate to the OD for pipes 14" and larger?
For pipes 14" and above, the outside diameter is exactly equal to the nominal
pipe size ($OD = NPS$).
6. What is meant by the term "Wall Thickness"?
Wall thickness refers to the thickness of the metal used to manufacture the pipe;
it is also commonly referred to as the pipe's "weight."
7. What were the three original manufactured weights for pipe?
The original weights were Standard (STD), Extra Strong (XS), and Double
Extra Strong (XXS).
, 8. Why were "Schedules" developed to replace or supplement original
weights?
New chemical processes, corrosive commodities, high temperatures, and
extreme pressures required a wider variety of wall thicknesses to ensure safe
operation.
9. What is the mathematical formula used to calculate a pipe's Inside
Diameter (ID)?
The formula is:
$$ID = OD - (2 \times \text{Wall Thickness})$$
10.What factors must be considered before selecting a specific pipe?
Engineers must consider the material, temperature and pressure allowances, and
corrosion resistance.
11.What are the risks of selecting the wrong pipe size or schedule?
Selecting a pipe below minimum requirements is dangerous and potentially
deadly, while over-specifying leads to massive cost overruns.
12.What does the pipe "Schedule Number" indicate?
The schedule number relates to wall thickness: as the schedule number
increases, the wall thickness becomes thicker.
13.Does a Schedule 40 rating mean the wall thickness is the same for all pipe
sizes?
No. While the schedule number remains the same, the actual wall thickness
increases as the nominal pipe size increases (e.g., 2" Sch 40 is thicker than 1"
Sch 40).
14.What are the most common pipe schedules used in the industry?
While schedules range from 5 to 160, the most common are Schedule 40 and
Schedule 80.
15.If the schedule number of a pipe changes, what physical measurement
remains constant?
VERIFIED ANSWERS PASS GUARANTEE
1. What are the three different categories used to identify pipe size?
Pipe is identified by Nominal Pipe Size (NPS), Outside Diameter (OD), and
Inside Diameter (ID).
2. How is Nominal Pipe Size (NPS) defined in process piping?
NPS identifies a pipe by name only. Much like a "2x4" piece of lumber, the
name refers to the pipe's identity rather than its exact measurement.
3. What do the terms Outside Diameter (OD) and Inside Diameter (ID)
represent?
OD and ID refer to the actual physical measurements of the pipe's exterior and
interior, respectively.
4. How does the NPS relate to the OD for pipes sized between 1/8" and 12"?
For pipes in this range, the actual outside diameter is greater than the nominal
pipe size ($OD > NPS$).
5. How does the NPS relate to the OD for pipes 14" and larger?
For pipes 14" and above, the outside diameter is exactly equal to the nominal
pipe size ($OD = NPS$).
6. What is meant by the term "Wall Thickness"?
Wall thickness refers to the thickness of the metal used to manufacture the pipe;
it is also commonly referred to as the pipe's "weight."
7. What were the three original manufactured weights for pipe?
The original weights were Standard (STD), Extra Strong (XS), and Double
Extra Strong (XXS).
, 8. Why were "Schedules" developed to replace or supplement original
weights?
New chemical processes, corrosive commodities, high temperatures, and
extreme pressures required a wider variety of wall thicknesses to ensure safe
operation.
9. What is the mathematical formula used to calculate a pipe's Inside
Diameter (ID)?
The formula is:
$$ID = OD - (2 \times \text{Wall Thickness})$$
10.What factors must be considered before selecting a specific pipe?
Engineers must consider the material, temperature and pressure allowances, and
corrosion resistance.
11.What are the risks of selecting the wrong pipe size or schedule?
Selecting a pipe below minimum requirements is dangerous and potentially
deadly, while over-specifying leads to massive cost overruns.
12.What does the pipe "Schedule Number" indicate?
The schedule number relates to wall thickness: as the schedule number
increases, the wall thickness becomes thicker.
13.Does a Schedule 40 rating mean the wall thickness is the same for all pipe
sizes?
No. While the schedule number remains the same, the actual wall thickness
increases as the nominal pipe size increases (e.g., 2" Sch 40 is thicker than 1"
Sch 40).
14.What are the most common pipe schedules used in the industry?
While schedules range from 5 to 160, the most common are Schedule 40 and
Schedule 80.
15.If the schedule number of a pipe changes, what physical measurement
remains constant?
