Piping Piping Supports and Hangers 2 — Questions and Answers
Question 1: What is a 'constant support hanger' designed to maintain?
- Constant pipe temperature
- A constant supporting force throughout the pipe's range of vertical travel (Correct answer)
- Constant fluid pressure in the pipe
- Constant spacing between supports
Correct answer: A constant supporting force throughout the pipe's range of vertical travel
Constant support hangers use a spring-counterweight mechanism to maintain a nearly constant supporting force regardless of the pipe's vertical position.
Question 2: A pipe guide support differs from a pipe anchor in that a guide:
- Allows axial movement but restricts lateral movement (Correct answer)
- Restricts all movement
- Only supports vertical loads with no lateral restraint
- Is used exclusively on underground piping
Correct answer: Allows axial movement but restricts lateral movement
A guide permits movement along the pipe axis (axial direction) while restraining lateral and sometimes vertical movement to keep the pipe aligned.
Question 3: According to ASME B31.3, when calculating maximum span between supports for liquid-filled process piping, the designer must consider:
- Only the weight of the empty pipe
- Both the pipe weight and the weight of fluid, insulation, and allowable sag (Correct answer)
- Only the internal pressure rating
- Only the thermal expansion forces
Correct answer: Both the pipe weight and the weight of fluid, insulation, and allowable sag
Span calculations must account for the combined dead weight of pipe, fluid contents, insulation, and any other attachments, while keeping deflection within allowable limits.
Question 4: What is a 'snubber' used for in piping systems?
- To reduce noise from flowing fluid
- To restrain dynamic loads such as seismic or water hammer while allowing slow thermal movement (Correct answer)
- To insulate the pipe from structural steel
- To increase the support span
Correct answer: To restrain dynamic loads such as seismic or water hammer while allowing slow thermal movement
Snubbers (hydraulic or mechanical) lock under fast dynamic loads like earthquakes or water hammer, yet release slowly to allow thermal movement.
Question 5: Which MSS SP standard specifically covers the selection and application of pipe hangers?
- MSS SP-58
- MSS SP-69 (Correct answer)
- MSS SP-75
- MSS SP-44
Correct answer: MSS SP-69
MSS SP-69 covers the selection and application of pipe hangers and supports, while SP-58 covers their design and manufacture.
Question 6: When a pipe support must be placed on a structure that also experiences vibration, the preferred support type is:
- A rigid rod hanger
- A variable spring hanger
- A vibration isolation hanger with elastomeric elements (Correct answer)
- A clevis hanger without any dampening
Correct answer: A vibration isolation hanger with elastomeric elements
Vibration isolation hangers incorporate elastomeric (rubber) pads or springs that absorb vibration energy and prevent it from transmitting between the pipe and structure.
Question 7: The 'hot load' of a spring hanger is defined as the load carried by the hanger:
- During a hydrostatic pressure test
- At the operating (hot) temperature of the system (Correct answer)
- During summer ambient conditions
- When the system is shut down
Correct answer: At the operating (hot) temperature of the system
Hot load is the design supporting force the spring hanger must exert when the piping system is at its normal operating temperature.
Piping Piping Supports and Hangers 2
What is a 'constant support hanger' designed to maintain?