Change diameter of pipes with no center polyline

Is there a comand in rhino which allows you to change the diameter of a pipe without using a ceteral polyline?

You can just edit the control points of your pipe.
Take all the control points in the U or V direction (which correspond to a section of your pipe) and scale them.


This might be of help to reconstruct the centerline:

use offset surface to make it thicker/thinner, delete input.