- . Choose Geometry->Delete->Volumes and select the two volumes, to be able to delete some of its unwanted surfaces.
Note: verify that 'Also lower entities' of the delete menu is not set, otherwise its surfaces, lines and points will be deleted.
- . Choose Geometry->Delete->Surfaces and select the small surfaces inside the first pipe. Select Lower Entities in the contextual menu, to delete its dependencies also. Press ESC to conclude the process of selection.
Surfaces to be deleted
Delete the rest of unwanted surfaces to left only the skin of a volume.
- . Use Geometry->Create->Volume->By contour and select all surfaces
The volume of a T junction
- . From the Files menu, select Save to save the file. Enter a name for the file and click Save.