Applies To
Product(s):	AutoPIPE
Version(s):	ALL;
Area:	Modeling
Date Logged & Current Version	April 2019 12.00.00.14

Problem:

How to model a Double trunnion on a Bend using AutoPIPE?

Solution:

Use the following suggested modeling approach:

1. Insert a Bend with the appropriate bend radius and pipe properties.

2. Open the Bend dialog

3. A bend is made up of 4 points:

Near Point
Mid Point
TIP Point
Far Point

This modeling approach will connect the double trunnion support to the Bend's Mid point.

a. Open the Bend dialog

b. Enable the Midpoint check box

c. Set the "Percentage around the bend" as need to locate the center axis connection to the double trunnion support. This may be an iterative process as this value is based on a percentage around the radius of the bend instead of a arc distance.

d. Press OK to continue

4. Make the Bend's Midpoint the active point (ex. A01 M)

5. Model internal rigid beams with no weight from the pipe center line to the outside surface of the carrier pipe

Insert a Beam, section ID = 0 (default Beam property) tot he location where the trunnion will be welded the the carrier pipe (ex. global X-axis, 8" pipe, radius = 4.3125", node point = MR01).

6. Repeat steps 5, adding a 2nd trunnion in the opposite direction (ex. global -X-axis, node point = ML01)

8. At this point the user has a choice to make, model trunnion support

a. Using Piping components

b. Using Beam member components

Model Using Piping Components

a. Insert new Pipe Properties (ex. Trunnion) to represent the characteristics of the trunnion piping being welded to the elbow.

Note: Specific gravity = 0.00 because trunnion piping will be opened to the atmosphere and not the process side of the carrier pipe.

b. Make beam point the active node point (ex. MR01 / ML01)

c. Insert segment starting at the beam point (ex. MR01 / ML01), and set Pipe Data Identifier equal to newly created pipe property above (ex. Trunnion).

d. Insert pipe Run to support location as needed (ex. 2 ft)

e. Insert Support or connect to other structural Beams.

f. Repeat steps B to E adding a 2nd trunnion in the opposite direction.

g. Last step, make the Bend's Midpoint the active point (ex. A01 M), insert a User SIF .

Consider one of the 3 options below:

i. Use AutoPIPE to help calculate the SIF value by actually modeling a temporary TEE with the same geometry to one side (ex. Type = Reinforced with Pad).

The program will calculate the SIF for a non-User type of tee and display the results in the output report or on the Tee tab on the input grids. Afterwards the temporary Tee can be deleted.

ii. Hand calculate the value.

iii. Use another application to calculate the SIF values.

Note: If the stresses at this location are a concern, suggest to perform a WRC 107 / 297 analysis using AutoPIPE Nozzle or, model in a full FEA application.

Model Using Beam Components

a. Insert new Beam Properties (ex. Trunnion) to represent the characteristics of the trunnion piping being welded to the elbow (ex. trunnion piping will be 8in Sch 40 pipe.)

b. Make the beam point the active node point (ex. MR01 / ML01)

c. Insert Beam to support location as needed (ex. 2 ft)

d. Insert Support or connect to other structural Beams.

f. Repeat steps B to D adding a 2nd trunnion in the opposite direction.