	Applies To
	Product(s):	AutoPIPE,
	Version(s):	All
	Area:	modeling
	Original Author:	Bentley Technical Support Group

Dec 2014, AutoPIPE V8 09.06.01.10

Problem:

In the piping industry, Trunnions are short structural members (usually round pipe) welded to the outside surface of process piping to be used as a support. Trunnions can be mounted to one or both sides of the process piping. The general area around the trunnion location on the process piping will be prepared for welding, however there will no thru wall cutting of the process piping. Again, the main function of a trunnion will be supporting gravity load of the piping system

How to model a Trunnion pipe support in AutoPIPE?

Solution:

There a couple different methods of modeling a Trunnion support in AutoPIPE. However, depending on the location of the trunnion support (ex. straight pipe, valve, bend, tee, etc..) there may be some limitations on which approach will be best suited. Consider using one or a derivation of the following methods:

Option #1: AutoPIPE Help modeling approach

Please see the following AutoPIPE help section:

Help > Contents> Contents Tab> Modeling Approaches> Modeling Approaches> Support> Model 2: Trunnion Support

Option #2: Model with Beam Members only

Model a rigid Beam that does not include weight from the center of the pipe to the outside surface of the pipe.

From this point, add another beam with specific section properties to the actual support location (i.e. anchor component or another beam that is part of a structural support system built in the model).

Option #3: Model with both Beam and Piping

Similar to the Option #2 above, but with Piping components.

a. Insert a Tee component at the node point, Tee type = Other, SIF in/ out = 1.00.

b. On the Tee Branch insert a run of pipe to the outside surface of the main pipe run

c. Select this short run of Pipe, Insert> Rigid options over range> :

Include Weight = unchecked (OFF)

Include Thermal Expansion = checked (ON)

Wire frame View below:

d. From the node point located on the surface of the pipe, insert User SIF value representing the welded connection and insert a pipe run, using updated pipe properties, to the actual support location (i.e. anchor component or another beam that is part of a structural support system built in the model).

e. At the pipe surface interface where the trunnion is connected to the pipe insert a Reference Point:

AutoPIPE V8i 09.06.01.xx and lower: Insert> Xtra Data> Reference Point> with "Report Reference Points results to AutoPIPE Nozzle/AutoPIPE Vessel" option checked ON.

With AutoPIPE Advanced or Nuclear edition, using File> Export> Nozzle Loads to AutoPIPE Nozzle> evaluate stresses of trunnion on pipe.

08. How to model a Trunnion welded structural pipe support in AutoPIPE?

Problem:

Solution:

Option #1: AutoPIPE Help modeling approach

Option #2: Model with Beam Members only

Option #3: Model with both Beam and Piping

See Also