Expander system for incremental expansion of a tubular element

A method of radially expanding a tubular element using the expander system for radially expanding a tubular element having an unexpanded portion of a first inner diameter, the expander system including an expander movable between a radially retracted mode and a radially expanded mode, wherein the expander includes a tapering expansion surface extending in axial direction of the expander. the expansion surface being operable to expand the tubular element from said first inner diameter to a second inner diameter larger than the first inner diameter by movement of the expander from the retracted mode to the expanded mode thereof, said expansion surface being of increasing diameter in axial direction of the expander, comprising the steps of:

• a) arranging the expander within the tubular element;
• b) moving the expander from the retracted mode to the expanded mode thereof so as to expand the tubular element;
• c) moving the expander from the expanded mode to the retracted mode thereof;
• d) allowing the expander to move a selected distance through the tubular element by the action of an axial force exerted to the expander, said selected distance being smaller than the length of the expansion surface in axial direction of the expander;
• and
• e) repeating steps b)-d) until the expander has expanded the tubular element or a desired portion thereof, from the first diameter to the second diameter.