These are the steps required to to enable a jacketed vessels calculation:
Enable "Jacketed vessel option" under File > Item properties > Jacket tab. Define jacket conditions in the same window by switching to Operating conditions tab, then Jacket:
Design the vessel as you would normally do
When main shell - the one where jacket shall be applied to - is selected, "Add jacket" icon in the main toolbar is enabled:
By clicking on "Add jacket" icon the external cylinder of jacket is added. Fill in dimensions, material and set its L offset from the base of previously selected (point 3) main shell:
The jacket will be placed around main shell:
From now on it is possible to connect other elements constituting the whole jacket, e.g. heads, cones and closures: