Piping Engineering 3 — Questions and Answers
Question 1: What is the function of an expansion loop in a piping system?
- To increase system flow capacity
- To absorb thermal expansion and contraction without over-stressing the pipe (Correct answer)
- To trap and remove air from the line
- To reduce water hammer effects
Correct answer: To absorb thermal expansion and contraction without over-stressing the pipe
Expansion loops are U-shaped pipe sections that flex to accommodate dimensional changes caused by temperature variations, relieving thermal stress.
Question 2: Which flange facing type is most commonly used for standard pressure piping applications?
- Ring Type Joint (RTJ)
- Raised Face (RF) (Correct answer)
- Flat Face (FF)
- Tongue and Groove (T&G)
Correct answer: Raised Face (RF)
Raised Face flanges are the most widely used flange facing type in industrial piping, compatible with most gasket types and pressure classes.
Question 3: What does NPS stand for in piping specifications?
- Nominal Pipe Size (Correct answer)
- Net Pipe Strength
- National Pipe Standard
- Normal Pressure Schedule
Correct answer: Nominal Pipe Size
NPS (Nominal Pipe Size) is a North American standard designating pipe sizes, where the number does not necessarily equal the actual outside diameter.
Question 4: What is water hammer in a piping system?
- Condensate accumulation that causes pipe vibration
- A pressure surge caused by sudden change in fluid velocity (Correct answer)
- Corrosion pitting on the pipe interior
- Excessive pipe sag between supports
Correct answer: A pressure surge caused by sudden change in fluid velocity
Water hammer is a pressure transient that occurs when fluid flow is suddenly stopped or redirected, creating a shockwave through the piping system.
Question 5: In isometric drawings for piping, what does a spool represent?
- A prefabricated pipe assembly section (Correct answer)
- A type of pipe fitting reducer
- A pressure measurement device
- A support hanger component
Correct answer: A prefabricated pipe assembly section
A spool is a prefabricated piping assembly, typically consisting of pipe, fittings, and sometimes valves, fabricated in a shop and installed as a unit in the field.
Question 6: What type of corrosion occurs when two dissimilar metals are in contact in the presence of an electrolyte?
- Crevice corrosion
- Galvanic corrosion (Correct answer)
- Erosion corrosion
- Stress corrosion cracking
Correct answer: Galvanic corrosion
Galvanic corrosion occurs when two dissimilar metals form an electrochemical cell in the presence of an electrolyte, causing the more active metal to corrode preferentially.
Question 7: Which type of pipe end preparation is used for socket weld connections?
- The pipe end is beveled at 37.5 degrees
- The pipe is inserted into a female fitting socket and fillet welded (Correct answer)
- The pipe end is threaded using NPT threads
- The pipe end is flanged and bolted
Correct answer: The pipe is inserted into a female fitting socket and fillet welded
Socket weld fittings have a female socket that accepts the pipe end, which is then secured with a fillet weld on the outside of the fitting hub.
Piping Engineering 3
What is the function of an expansion loop in a piping system?