Pipefitter Valves, Fittings, and Pipe Materials 4 — Questions and Answers
Question 1: A reducing tee is used in a piping system to:
- Change flow direction 90 degrees on the main run
- Branch off a smaller pipe from a larger main line (Correct answer)
- Join two pipes of equal size at an angle
- Reduce pressure in a straight run
Correct answer: Branch off a smaller pipe from a larger main line
A reducing tee has a branch outlet smaller than the main run, allowing a smaller pipe to tap into a larger header.
Question 2: Which type of pipe joint is most suitable for underground gas distribution piping?
- Threaded connection
- Butt weld (Correct answer)
- Flanged connection
- Bell and spigot
Correct answer: Butt weld
Butt welding creates a continuous, leak-tight joint ideal for underground gas piping where access for maintenance is limited.
Question 3: Ductile iron pipe differs from gray cast iron pipe primarily in that it:
- Cannot handle water service
- Has greater tensile strength and impact resistance (Correct answer)
- Is lighter in weight
- Must be threaded, not bell-and-spigot
Correct answer: Has greater tensile strength and impact resistance
Ductile iron's microstructure (spheroidal graphite) gives it far greater tensile strength and toughness than brittle gray cast iron.
Question 4: A pressure relief valve on a steam boiler is set to open at:
- The normal operating pressure
- The maximum allowable working pressure (MAWP) (Correct answer)
- Twice the operating pressure
- The minimum supply pressure
Correct answer: The maximum allowable working pressure (MAWP)
Relief valves are set to open at or below the MAWP stamped on the boiler to prevent overpressure damage.
Question 5: Which fitting is used to close the end of a pipe with internal threads?
- Cap
- Plug (Correct answer)
- Coupling
- Union
Correct answer: Plug
A plug has external threads and is installed into the internally threaded end of a pipe or fitting to seal it.
Question 6: CPVC pipe is preferred over standard PVC for hot water distribution because it:
- Has better UV resistance
- Can handle higher temperatures up to approximately 200°F (Correct answer)
- Is less expensive
- Has a larger inside diameter
Correct answer: Can handle higher temperatures up to approximately 200°F
Chlorinated PVC (CPVC) is rated for continuous service up to approximately 200°F, making it suitable for domestic hot water systems.
Question 7: A union fitting is installed in a piping system primarily to:
- Increase pipe diameter
- Allow removal of equipment or pipe sections without cutting (Correct answer)
- Prevent reverse flow
- Reduce turbulence at branch connections
Correct answer: Allow removal of equipment or pipe sections without cutting
A union's three-piece design allows the line to be disconnected and reconnected without disturbing adjacent piping.
Pipefitter Valves, Fittings, and Pipe Materials 4
A reducing tee is used in a piping system to: