Journeyman Plumber ExamPlumbing Code and RegulationsMedium
A journeyman plumber is replacing a section of a potable water distribution pipe in a building. The existing pipe is galvanized steel, and the new section will be copper. According to the Uniform Plumbing Code (UPC), what fitting must be used to connect these two dissimilar metals to prevent accelerated corrosion?
- AA sweat-solder coupling
- BA standard threaded coupling
- CA dielectric union
- DA compression fitting
Show answer & explanationAnswer & explanation
Correct answer: C. A dielectric union
Connecting dissimilar metals like galvanized steel and copper directly can cause galvanic corrosion, leading to premature pipe failure. A dielectric union contains an insulating material that electrically separates the two metals, preventing this corrosive reaction.
Why the other options are wrong
- A. A sweat-solder coupling is for copper-to-copper connections or copper to brass, not copper to galvanized steel in this context.
- B. A standard threaded coupling would directly connect the metals, accelerating corrosion.
- D. A compression fitting would also create direct metal-to-metal contact, leading to corrosion.
Dissimilar Metal Connection
The method of joining two different types of metal piping to prevent galvanic corrosion.
- Galvanic corrosion occurs due to electrical potential difference.
- Dielectric unions provide electrical insulation.
- Required by plumbing codes to ensure system longevity.
Memory trick: Different metals, don't connect, a dielectric union earns respect.