| Applies To | |
| Product(s): | AutoPIPE |
| Version(s): | ALL; |
| Area: | Modeling |
| Date Logged & Current Version |
Sept 2020 12.04.00.13 |
Problem:
Find out how much external force would be needed to realign pipe back into original shape?
What will that extra external force applied to put the pipe back in place do to the piping during normal operation?
Solution:
There is no automated feature to solve this problem it will be an iterative approach.
Phase #1:
Save production model
Save model to Test01.DAT
Suggest to model the pipe in misaligned configuration. The closer to true misalignment the better.
Next, find the distance that the pipe end point must be displaced in order to return it back to the original intended configuration.
Using Measurement tool measure the distance between node points
0.38 feet = 4 9/16" = 116mm
Phase #2
Consider the 2 scenarios to determine required forces
Scenario #1: Iterative approach
Calculate or estimated what concentrated force (ex. 10,000 lbs) would be required to move the pipe back into original layout configuration.
Use Concentrated Force (Insert > Xtra Data > Concentrated Force) command to insert the first guess (suggest setting "Load case to combine with Force" = Gr or U1..Un load case).
Run the analysis and look at the results.
How much did the pipe displace under the first guess?
Next, adjust the inserted concentrated force as needed (ex. 16,800 lbs) until the pipe is displace to match pipe misalignment distance found above.
Document the final forces required.
Scenario #2: AutoPIPE determines initial guess
At misaligned node point, insert rigid Guide support, no gaps, no friction, Gap setting = As-built, connected to Ground
Add impose support displacement, insert movement required and direction, assign to GR load case
Analysis set, only add GR / Uxx load case.
Save the model. and Analyze model.
Review Guide support forces, moments, displacements.
This represent the theoretical force required to displace the pipe into realignment.
Delete Guide support
Insert Concentrated Force (Insert > Xtra Data > Concentrated Force) at misaligned node point, enter values from approach above.
Again, analyze the model.
Confirm the pipe displacement on the horizontal plain actually equals the desired amount. If not, use trial and error to adjust the forces until achieved the correct displacements.
Document the final forces required.
Question: Why use a guide instead of an anchor?
Answer: The benefit of using a Guide support over an anchor is that the guide support is always aligned perpendicular to the pipe, and will have no reaction in the axial direction of the pipe friction = 0.00 and Gap setting = As-built (see AutoPIPE help for details on this setting).
Phase 3:
Open the original model
Locate misaligned node points, insert Concentrated Force (Insert > Xtra Data > Concentrated Force) under GR or Uxx load case, and enter the values from the documented values above but in the opposite direction. Remember the pipe is resisting this movement and the force is now acting in the opposite direction.
Done.
Notes:
1. Analysis will consider these misaligned forces in each combination that uses Gr / Uxx load case.
2. Consider what load case to apply the concentrated forces:
a. Consider using gravity as the load would be applied during the cold condition before operating load cases.
b. Consider using User load case (ex. U1..Un). This way one can easily compare relative combination results to each other to understand how the miss alignment affected analysis results (only downfall of assigning miss-alignment concentrated force to User load case, would be the need to create additional User combinations).
Example: Sus compared to user defined combination Sus+U1