| Applies To | |||
| Product(s): | AutoPIPE, | ||
| Version(s): | ALL | ||
| Area: | Modeling. | ||
| Original Author: | Bentley Technical Support Group |
Problem:
How to model Jacketed Piping in AutoPIPE?
Solution:
Highly suggest to review the on-demand training video "Jacketed Pipe Design in AutoPIPE" available on the learn server.
Also, see the following AutoPIPE help section:
Help > Contents> Contents Tab> Modeling Approaches> Modeling Approaches> Pipes> Jacketed Pipe
1. First create the carrier pipe with locations for all spider / centralizer supports to be placed in the annular space.
2. Then easily create the Jacketed piping by using the Select with Copy / Paste commands. Select the range of carrier pipe, including valves, flanges, reducers etc, and paste the coped selection with a small offset (remember - no 2 node points in an AutoPIPE model should occupy the exacts same coordinates, us a small offset). After pasting, refine the jacketed piping by removing unwanted components and terminating the jacketed pipe to the carrier pipe with a short rigid beam member or connected anchor.
3. Insert spider supports / centralizers by selecting the carrier pipe location where the support would be located. Insert Support (i.e. guide, v-stop, etc..) with the proper gap settings but specify Connected to point as the corresponding point on the jacketed pipe.
This modeling technique is covered in AutoPIPE's Advanced training.
Notes: (read all notes below)
a. Carrier pipe and jacketed pipe modeled as two separate segments with different pipe identifiers e.g. Jacket16 and carrier8
b. Segments may be made of different materials and have different operating conditions
c. Carrier pipe is supported by the jacket at regular intervals using spacers (spider support) and at flanged ends.
d. Spacers are modeled as two point supports between a carrier segment point and a corresponding jacket segment point.
e. Modeling Fluid in Both the Jacketed and Carrier piping. Use caution when accounting for the weight of fluid in both the Carrier and Jacketed piping so as to not double count weight. See Modeling approach below to correctly account for fluid in both the Carrier and Jacket piping :
Modeling Approach:
1. Create a new PipeID for the section of Carrier pipe that is inside of the Jacket piping
2. Set this new Carrier PipeID SG = 1.00 (assuming water filled pipe).
3. Insert a new PipeID for the section of Jacket pipe covering the Carrier piping.
4.Set this Jacket PipeID SG to an equivalent SG = weight of liquid from Jacket Pipe ID volume - Carrier Pipe OD volume
This approach accurately accounts for the weight of fluid for both pipes.
f. Unless required by special circumstances, apply hydrodynamic (e.g. submerged piping), wind, or insulation properties to the Jacketed piping only,
g. For Vacuum Jacket pipe where the Jacket ends are welded or rigidly connected to the carrier pipe, suggest connecting the jacketed pipe to the carrier pipe with a short beam element or connected anchor.
h. For Jacketed pipe where the Jacket ends have a flexible seal / simple support connected to carrier pipe but the carrier pipe is still able to move axially independent of the Jacket, suggest connecting the jacketed pipe to the carrier pipe with a 2 point support (e.g. guide, incline, etc) or rigid / Flexible anchor(s) to each end of the Jacketed pipe.
i. New segment cannot be inserted at the start of a 2 point component like a valve. Therefore need to insert small run point before the valve to connect the jacketed piping segment. However, a new segments can be added at the end of the valve
j. Clash detection:
Inside of AutoPIPE, all components (pipe runs, flanges, valves, elbows,etc..) are considered to be a single beam element with known properties. These beam elements are only concerned about pipe properties and how their two end points are connected. There is no consideration of clash detection when one pipe touches another. Therefore a pipe run does not know that another pipe run has come into contact and to stop moving because of being restrained. The Pipe in a Pipe modeling approach has to account for the correct:
1. Total weight for gravity, seismic, and modal analysis
2. Total outside area affected by Wind, Waves, and buoyancy load case,
3. Correctly supporting the carrier pipe inside of the jacketed pipe. Then correctly supporting the jacketed pipe by soil or outside support system.
Bentley Navigator has a tool to automatically locate clash detection. A very useful tool for all but "Pipe in a Pipe" modeling technique. Navigator views both the carrier and jacketed pipe as a solid, thus clash detection is noted over the entire length of the modeling technique. There are rules that can be set but non of them would work for this specific situation, where one would want clashes to only be reported if the pipe wall clashes with the other pipe wall.
This would be important to understand, because piping is not self aware of clashing with another pipe, a clash detection study must be performed manually.
k. Consider taking an official AutoPIPE training class, this modeling technique would be covered in class with extra documentation.
l. For underground jacketed pipe, apply soil properties to the Jacketed (outside) pipe only, the carrier pipe inside of the jacket is supported by spacers, not soil. Again, confirm soil properties are only applied to the outside pipe for the length of jacketed piping underground.
m. Recommend setting pipe graphics to be transparent, View> Transparency> toggle the check box ON for Pipe, and press OK button. View model in solid model view, similar to screen shot above.
n. Model multiple carrier pipes using the same technique as shown above, connecting all carrier pipe supports to the same node point on the jacketed pipe.
o. Model jacketed piping where the annular space is filled with some material. Model the jacketed pipping as mentioned above. Account for insulation in annular space by using one of the following suggestions:
1. Carrier piping - add insulation thickness equal to the annular space between the 2 pipes. Then specify the density for the material. Set specific gravity of contents to what ever substance being conveyed.
or
2. Jacketed piping - add Lining thickness equal to the annular space between the 2 pipes. Then specify the density for the material. Set specific gravity of contents to 0.0.
Because AutoPIPE segments are not self aware of clash detection, the lining or insulation settings will not provide any support between the 2 piping segments. Insert Spider supports / centralizers to support the carrier pipe inside of the jacketed piping as mentioned above.
General Question:
1. Cryogenics uses a multi-layer insulation of conductive resistant and reflective material in combination a vacuum to eliminate conduction, convection, and radiation. Can AutoPIPE account for insulative properties of jacketed pipe with added insulation?
Answer:
AutoPIPE treats insulation as a mass and does not consider the insulation properties. For analysis such as inferred by the question above are better suited for full FEA applications like Bentley’s Adina. See link here for details about Adina capabilities to model complex design investigations. AutoPIPE's developers are working on integrating Adina into a future version of AutoPIPE.