Steamfitter Pipe Systems and Materials 1 — Questions and Answers
Question 1: What does the schedule number of a pipe (e.g., Schedule 40 or Schedule 80) indicate?
- The pipe's material alloy composition
- The pipe's wall thickness relative to its outer diameter (Correct answer)
- The pipe's maximum allowable working temperature
- The pipe's manufacturing year standard
Correct answer: The pipe's wall thickness relative to its outer diameter
Pipe schedule numbers indicate wall thickness — a higher schedule number means a thicker wall for the same nominal pipe size (NPS).
Question 2: Which pipe material is most commonly specified for steam distribution systems operating above 300°F?
- PVC (polyvinyl chloride)
- CPVC (chlorinated polyvinyl chloride)
- Carbon steel (Correct answer)
- Copper Type M
Correct answer: Carbon steel
Carbon steel is the standard material for high-temperature steam systems because it maintains strength and integrity well above 300°F, unlike plastics or soft copper.
Question 3: What does the Nominal Pipe Size (NPS) designation represent?
- The exact outer diameter of the pipe in inches
- The exact inner diameter of the pipe in inches
- An approximate reference dimension historically related to inner diameter (Correct answer)
- The pipe's wall thickness in fractions of an inch
Correct answer: An approximate reference dimension historically related to inner diameter
NPS is a nominal (approximate) designation that historically referenced the inner diameter; for NPS 14 and larger, the NPS actually equals the outer diameter in inches.
Question 4: A steamfitter needs to change the direction of a pipe run by exactly 45 degrees. Which fitting is used?
- 90-degree elbow
- 45-degree elbow (Correct answer)
- Street elbow
- Lateral tee
Correct answer: 45-degree elbow
A 45-degree elbow changes pipe direction by 45 degrees and is a standard fitting used to offset pipe runs at that angle.
Question 5: What is the primary purpose of a union fitting in a piping system?
- To reduce the pipe to a smaller diameter
- To allow the piping to be disconnected without cutting (Correct answer)
- To increase flow velocity through the system
- To prevent backflow in a single direction
Correct answer: To allow the piping to be disconnected without cutting
A union allows a section of pipe or component to be easily removed and reconnected by unthreading the union nut, without cutting or unthreading long pipe runs.
Question 6: Which organization publishes the ASTM standards that specify material requirements for steel pipe used in pressure applications?
- ASTM International (Correct answer)
- IEEE (Institute of Electrical and Electronics Engineers)
- OSHA (Occupational Safety and Health Administration)
- EPA (Environmental Protection Agency)
Correct answer: ASTM International
ASTM International publishes pipe material specifications such as ASTM A53 for black and hot-dipped steel pipe and ASTM A106 for seamless carbon steel pipe for high-temperature service.
Question 7: Which pipe material is typically used for condensate return lines in a steam heating system?
- Galvanized steel pipe
- Black steel pipe (Correct answer)
- Schedule 40 PVC
- Type L copper
Correct answer: Black steel pipe
Black steel pipe is standard for condensate return lines because it resists the corrosive nature of hot condensate; galvanized pipe can release zinc into the system and is not recommended for steam service.
Steamfitter Pipe Systems and Materials 1
What does the schedule number of a pipe (e.g., Schedule 40 or Schedule 80) indicate?