Piping Components 3 — Questions and Answers
Question 1: What is the difference between a concentric reducer and an eccentric reducer?
- Concentric reducers are used for gas; eccentric reducers are used for liquids
- A concentric reducer has aligned centerlines; an eccentric reducer has offset centerlines (Correct answer)
- Concentric reducers are threaded; eccentric reducers are welded
- A concentric reducer reduces by one size; an eccentric reducer reduces by two sizes
Correct answer: A concentric reducer has aligned centerlines; an eccentric reducer has offset centerlines
In a concentric reducer the centerlines align on the same axis, while an eccentric reducer has offset centerlines, keeping one side flat.
Question 2: Which type of pipe cap is used on a pipe end that may need to be reopened later?
- Welded cap
- Threaded cap (Correct answer)
- Crimped cap
- Compression cap
Correct answer: Threaded cap
A threaded cap can be removed and reinstalled without cutting pipe, making it ideal for pipe ends that may need future access.
Question 3: What is the purpose of a pipe coupling?
- To change the direction of flow in a pipeline
- To join two pieces of pipe of the same diameter end to end (Correct answer)
- To reduce the pipe size from large to small
- To branch a single pipe into two separate lines
Correct answer: To join two pieces of pipe of the same diameter end to end
A coupling is a short fitting used to connect (couple) two pipes of the same size together in a straight run.
Question 4: A 'street elbow' differs from a standard elbow because it has:
- A longer radius than a standard elbow
- One male (external) threaded end and one female (internal) threaded end (Correct answer)
- Two female threaded ends and a swivel connection
- A 45-degree angle instead of 90 degrees
Correct answer: One male (external) threaded end and one female (internal) threaded end
A street elbow (also called a service elbow) has one male-threaded end and one female-threaded end, eliminating the need for a nipple.
Question 5: In piping systems, what is a 'bushing' used for?
- To seal the end of a pipe run permanently
- To reduce a female fitting opening to accept a smaller male pipe or fitting (Correct answer)
- To connect two pipes of the same diameter
- To allow pipe expansion and contraction
Correct answer: To reduce a female fitting opening to accept a smaller male pipe or fitting
A bushing is a type of reducer fitting with male threads on the outside and female threads on the inside, used to reduce a fitting's port size.
Question 6: What type of fitting is used to connect plastic pipe to metal pipe in residential plumbing?
- A standard slip coupling
- A dielectric union or transition fitting (Correct answer)
- A street elbow
- A reducing bushing
Correct answer: A dielectric union or transition fitting
A dielectric union or transition fitting prevents galvanic corrosion between dissimilar metals (or metal and plastic) at the connection point.
Question 7: What is the function of a plug fitting in a piping system?
- To regulate flow rate through the pipe
- To close off a female-threaded opening in a fitting or pipe (Correct answer)
- To join two sections of pipe at an angle
- To allow pipe to expand and contract with temperature changes
Correct answer: To close off a female-threaded opening in a fitting or pipe
A plug is a male-threaded fitting used to seal or close off a female-threaded port in a valve, tee, or other fitting.
Piping Components 3
What is the difference between a concentric reducer and an eccentric reducer?