| Applies To | |||
| Product(s): | AutoPIPE, | ||
| Version(s): | 2004, XM, & V8i | ||
| Area: | Modeling | ||
| Original Author: | Bentley Technical Support Group |
Dec 2014, AutoPIPE V8i 09.06.01.10
Problem:
Would like to know the explanation about the line stop ignoring friction. In my opinion, this is not feasible especially when the line stops are placed nearby the nozzles. Moreover, high temperature lines usually have high line stop loads to produce high frictional forces in the other 2 directions. These are being ignored by AutoPipe.
Solution:
Based on typical construction practice, a line stop is usually a lug or some kind of an attachment rigidly mounted to and moves with the pipe in the axial direction. Most line stops have a predetermined gap for axial movement. When the pipe's axial movement is such that the gap closes, the lug / attachment will now be in contact with a rigidly supported item (i..e concrete block, beam structure, etc..) that will prevent further movement in the direction of travel. This type of support is called a Line Stop
A Line stop has no friction involved as the lug / attachment is rigidly mounted to the pipe where it freely moves with the pipe. Also a pipe is not supported by a line stop, so there is no bearing force on a line stop support. The only contact for a Line stop is when the gap closes and it is resting against the anchor object.
Per the image above, there are 2 supports shown.
a. I-Beam: Vertical pipe support
b. Lug attachment: Line stop with predetermine gap
Any axial pipe movement would generated Friction force on the I-beam support (Vstop) not the Line stop support.. Therefore, enter friction coefficient on he V-sop not the Line stop.