An older house has galvanised steel water supply pipes. What is the typical way this piping fails?
- It becomes brittle in sunlight and cracks along its length
- It softens with hot water and sags between its hangers
- It reacts with chlorine and splits at its crimped fittings
- It rusts from the inside, cutting flow and finally leaking
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D. It rusts from the inside, cutting flow and finally leaking
The zinc coating wears away and the steel rusts internally; the build-up narrows the bore so flow drops, and leaks appear at threads and thin spots. Splitting at fittings from chlorine is associated with polybutylene, not steel.
Reference: Plumbing: galvanised steel supply piping deterioration
Which of these conditions on a water heater relief valve discharge pipe is a defect?
- The pipe runs downhill for its entire length
- The pipe is smaller than the valve outlet
- The pipe is made of copper and ends near the floor
- The pipe has an open, unthreaded lower end
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B. The pipe is smaller than the valve outlet
The discharge pipe must be full size, slope down to drain by gravity, have no valve or cap, and end where discharge is visible and safe. Reducing its size restricts the flow the valve needs to relieve. The other three choices describe a correct installation.
Reference: IPC 2021 504.6 (relief valve discharge piping, concept)
Why is an S-trap under a sink reported as a defect?
- It holds too much water and breeds bacteria in the seal
- It cannot be taken apart for cleaning when it clogs
- It makes waste flow so slowly that solids settle out
- It can siphon itself dry and let sewer gas into the room
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D. It can siphon itself dry and let sewer gas into the room
In an S-trap the outlet drops straight down with no vent at the trap arm, so a full flow of water can siphon the seal out of the trap. A properly vented P-trap keeps its seal.
Reference: IPC 2021 1002.3 (prohibited traps)