Question: 

How to model a Horizontal Vessel with jacketing 2/3 the distance around the outside? 

Example:

Answer: 

As of November 2024, AutoPIPE Vessel does not cover this type of jacketed vessels.
Workaround

Option #1: Model the complete jacketed vessel

or

Option #2: Model two separate vessel. 

Users need to create a model with the internal chamber only. Model the nozzles attached to it too. Remove any support. Use the internal P/T of the jacket as external P/T for these elements. Run calculation and get the weights from the summary.

In a second and independent file, model the jacket shell with its nozzles and saddles. User needs to add the missing weight from the internal chamber, since a distributed load is not yet available (will be v2025), user has 2 options: add is as point loads (Menu>Insert> Loads), add it as a lining (this is more accurate as it will simulate a distributed load but requires some effort to adjust lining values to get the proper weights)