16. How to model 4 or 6 way branch manifold / junction using AutoPIPE?

Applies To
Date Logged
& Current Version
Jan 2023


How to model 4 or 6 way branch manifold / junction using AutoPIPE?


When trying to model an unusual component, try to understand the basic requirements and think about how to assemble AutoPIPE's components to match these requirements. 

In this case what are the requirements:

1. All of the pipes connected to the header / manifold are essentially connected to the same node point at the center.

2. The header / manifold is a block of steel

3. Each face of the header / manifold would be rigidly connected to the center.

4. Should thermal expansion be applied to the header / manifold

5. How to consider the weight of contents?

Does one assume the contents weight is the same as six pipes, with the same nominal dia. as connecting pipes, from edge of the block to the center, if no, then how to account for contents.

6. How to account for the weight of the actual header / manifold?

7. What is the SIF for the connection at the center of the block or Tee connection?


What modeling techniques could one use to model such a component?

Correct, model the header / manifold as a series of pipes or as series of beams with specific properties. 

Using Pipe components

a. Define a new pipe property with the same pipe diameter as the pipe that will be connected and set both Specific gravity of contents and Density = 0.

b. Insert a New Segment that starts at the center of the component. 

c. Insert run from the center of the component to the flange connection. (ex. Dx = 9 inches)

d. Insert new segment, again starting point it the center of the component

e. Repeat step above until all all 6 segments are protruding from the center to the face of the component. 

f. Select all piping that make up the component and Insert Rigid Options Over Range with he following settings:

g. Consider the SIF values.

1. Since the manifold / junction is assumed to be infinitely rigid, override all axial, torsional, In-plane, and Out-plane SIF's at the center point of the manifold / junction with user defined value = 1.0. 

2. Please SIF at the face of the connections as needed. 

h. Consider Weight

1. Select the center of the component and insert weight equal to that of the manifold / junction block

2. Select the center of the component and insert weight equal to that of the contents with in the manifold / junction block

I. Done!!!

Copy and paste the manifold / junction block around the model as needed, and connect segment to the faces as needed.

Using Beams components

Much like those instructions above, the construction of the Manifold / Header is the same, just using beams.

Using Beam Section ID = 0 construct the Manifold header (note, one may insert a new Beam section id that matches Beam Id = 0, but change the shape reference to be a little more pleasant). 

One disadvantage is that a segment must be present to insert a flange component. This can be time consuming with having to model both pipe segments and Beam section in all 6 directions.

For this reason, best to model Manifold / Header components with piping components instead of Beam components. 

See Also

Tee, Cross, or Branch Piping Components - Modeling Approaches

Bentley AutoPIPE