How to model flexible hose floating on surface of water using AutoPIPE
Suggested modeling approach.
1. Insert 2 different pipe properties,
a. Pipping on land up to the water's edge.
b. Hose floating on the water.
Note, be sure to enter the correct Specific gravity of contents and other values as needed to best represent the type of piping being modeled.
2. Model piping segments on land to the water's edge using respective PipeID (optionally, insert anchors at waters edge if needed / present).
3. Insert a new pipe segment using water PipeID and model hose across the water. Typically flexible hose is modeled with multiple flexible joints. See WIKI here and here. Suggestions for flexible joint values are mentioned on the WIKI pages.
4. At the other side where the hose / piping transitions back to land insert a new segment with the respective PIpeID for land (optionally, insert anchors at waters edge if needed / present).
5. Insert Buoyance load (Loads > Environmental > Buoyancy) on the water segment only
Insert values as needed on the dialog.
Note: Individual segments can have buoyancy turned on/off by using the "Apply Buoyancy" option in the Segment input grid.
5. Optional, determine if model is going to have Wave loading applied. If yes continue below:
Use Wave (Loads > Environmental > Wave) command and enter values as necessary. The wave load data must be assigned to a static load case for analysis. Typically the User cases U1 to U140 are used first to define a wave loading. Be sure to add these load cases when configuring analysis sets.
Note, at this time, wave loading is applied to all piping at / below the water surface. Use Water Surface (Show > Labels > Water Surface) command to graphically see the water level.
6. Optional, The Hydrodynamic Data command (Insert > Xtra Data > Hydrodynamic Data) enables the user to override the hydrodynamic factors (Cm, Cd and Cl) determined automatically by AutoPIPE when calculating wave forces at a current point. Configure dialog as needed for analysis.
7. Save model, run analysis, and review results.
In conclusion, modeling hose floating on water is fairly straight forward. Start modeling the piping on land as separate piping segments with the correct elevations and PipeID, insert new pipe segment and model hose as flexible joint(s) with the correct PipeID, be sure to configure the flexible joint(s) with the correct properties, then insert buoyance load, and optionally add Wave loading / Hydrodynamic data as needed.
One important point, the buoyance load does not stop at the water surface. If no weight is added to offset the buoyance force It will be continuously applied to the piping above the water surface until restrained by pipe properties or other. Therefore it is highly important to model all items above correctly. IF the pipe was found to displace above the water level after confirmation of values, determine / calculate the restoring load required and apply it section of model crossing the water as a distributed load or concentrated force combined with the Gravity load case.
Flexible Joint - Modeling Approaches, Tips, Techniques