PC Plumber Pipe Installation & Repair 2 — Questions and Answers
Question 1: When installing copper pipe with soldered joints, what is the minimum distance a solder joint must be from a previously made joint to prevent overheating?
- 1 inch
- 2 inches
- 4 inches (Correct answer)
- 6 inches
Correct answer: 4 inches
A minimum of 4 inches between solder joints prevents heat transfer from remelting previously made joints.
Question 2: Which type of pipe is best suited for underground water service lines due to its flexibility and corrosion resistance?
- Galvanized steel
- Type K copper (Correct answer)
- PVC Schedule 40
- Cast iron
Correct answer: Type K copper
Type K copper has the thickest wall of all copper types and is rated for underground and exterior water service applications.
Question 3: A homeowner reports banging noises when shutting off faucets quickly. What is the most likely cause?
- Loose pipe hangers
- Water hammer (Correct answer)
- High water pressure
- Air in the lines
Correct answer: Water hammer
Water hammer occurs when fast-closing valves abruptly stop water flow, creating a pressure shockwave that causes pipes to bang.
Question 4: What is the correct slope for horizontal drainage pipe to ensure proper flow without solids settling?
- 1/16 inch per foot
- 1/8 inch per foot
- 1/4 inch per foot (Correct answer)
- 1/2 inch per foot
Correct answer: 1/4 inch per foot
A slope of 1/4 inch per foot provides adequate velocity to carry solids through horizontal drainage pipes.
Question 5: When making a repair to a leaking galvanized steel pipe, which fitting allows you to remove a section of pipe without turning the entire run?
- Coupling
- Union (Correct answer)
- Tee
- Nipple
Correct answer: Union
A union consists of three pieces that allow pipe sections to be disconnected and reconnected without rotating the entire pipe run.
Question 6: What type of pipe support should be used when running copper water supply lines through holes in wood framing to prevent electrolytic corrosion?
- Steel pipe straps
- Copper pipe clamps
- Plastic-lined or dielectric hangers (Correct answer)
- Galvanized wire
Correct answer: Plastic-lined or dielectric hangers
Plastic-lined or dielectric hangers prevent direct metal-to-metal contact that can cause galvanic corrosion between dissimilar metals.
Question 7: Which repair method is appropriate for a pinhole leak in a copper pipe in an accessible location when a full section replacement is not feasible immediately?
- Wrap tightly with electrical tape
- Apply a pipe repair clamp (Correct answer)
- Use putty epoxy only
- Solder over the hole without cleaning
Correct answer: Apply a pipe repair clamp
A pipe repair clamp provides a reliable temporary fix by compressing a rubber gasket over the leak using a metal sleeve.
PC Plumber Pipe Installation & Repair 2
When installing copper pipe with soldered joints, what is the minimum distance a solder joint must be from a previously made joint to prevent overheating?