Hi Peter, I don't have the exact details, but I can point to you the area where it is controlled. As in the attached screenshot, the Connections, Joint Settings, Flanged determine the fasteners used for a flanged joint. The default is gaskets and bolts. You would need to define a new joint type for the rubber lined flanges where the fasteners are only bolts. Now we need to differentiate between flanged and rubber lined flanged, this would require creating a new end type (say RFL) which I think not possible in UI and you might have to edit the DefaultConnectorsConfig.xml in the project file. Inside the catalog editor, the valve face might also need to be defined as RFL. I am just explaining the theory that I know, haven't tried such a thing before and not sure if all these can work well. Good luck with your testing.
Thanks, Siva (Autodesk)