An expander is provided for radially expanding a tubular element, the expander having an axially forward direction and being provided with thrust means for exerting a thrust force to the expander to move the expander in axially forward direction through the tubular element. The expander comprises an adjustable cone having an expander surface tapering radially inward in the axially forward direction, the adjustable cone being movable between a radially expanded mode and a radially collapsed mode. The expander further comprises adjusting means for moving the adjustable cone from the collapsed mode to the expanded mode by the action of said thrust force exerted to the thrust means.