Overview:Comments, Questions, and Answers about modeling approaches for "Bends"
Please see the following AutoPIPE help section:
Help > Contents> Contents Tab> Modeling Approaches> Modeling Approaches> Vessels
Question:
In the modeling approach, Step 11 note, "Note: To transfer loads to AutoPIPE Nozzle, currently the vessel must be modeled as an anchor at A06 ". Why must I do this?
Answer:
As of May 2023, AutoPIPE has the ability to transfer the forces and moments to another program called AutoPIPE Nozzle. AutoPIPE Nozzle overview:
Bentley AutoPIPE Nozzle is software for the calculation of local stresses at nozzle/vessel junctions, trunnion attachment points, clip connections, and lug attachments on the shell. Based on these well-known engineering ASME, British, API, and Japanese design standards, Bentley AutoPIPE Nozzle helps engineers and designers quickly determine whether or not the wall of a pressure vessel, exchanger, or tank can withstand piping loads on the nozzle or withstand loads at clip and lug connections.
With that said, the only AutoPIPE components that can transfer loads to AutoPIPE Nozzle are: a. Anchor or b. Reference Point. Please know that this Vessel modeling approach was written long before the introduction of the Reference Point component. This Vessel approach may need to be updated with the following information.
Here are the following modeling options for transferring Vessel Nozzle loads to AutoPIPE Nozzle:
Modeling approach 1:
Insert a Rigid anchor at A06, and enable the "Report Reference Point Results to AutoPIPE Nozzle/AutoPIPE Vessel" option at the bottom of the dialog. Be sure to delete piping components beyond A06 and Vessel segment.
This could be considered an overly conservative approach, because everything is rigidly mounted with no credit take for flexibility or movement of the vessel.
Modeling approach 2:
If the nozzle flexibility components have been pre-calculated, they can be modeled directly by defining a flexible anchor A06, and enable the "Report Reference Point Results to AutoPIPE Nozzle/AutoPIPE Vessel" option at the bottom of the dialog. Next, as mentioned in the modeling approach, add applied displacements in the GR, T1 etc load cases. Finnaly, be sure to delete piping components beyond A06 and Vessel segment.
This option takes credit for the for flexibility of the vessel and movement of the vessel based on external calculations.
Modeling approach 3:
Follow the modeling approach as mentioned, insert a Reference Point at A06 and enable the "Report Reference Point Results to AutoPIPE Nozzle/AutoPIPE Vessel" option at the bottom of the dialog.
This approach takes full credit for flexibility and movement of the vessel. The advantage of this approach calculations of nozzle flexibility and movement are all calculated within AutoPIPE.
***Cation*** - When using Approach 2 or 3 above the user should understand that the Forces and Moments calculated in AutoPIPE are dependent on the settings within the model. The user is cautioned to carefully mimic those settings when modeling in AutoPIPE Nozzle. Otherwise the nozzle stiffness portrayed in AutoPIPE Nozzle does not match that in AutoPIPE thus making the forces and moments calculations transferred from AutoPIPE incorrect.