Patent ID: 7464764

Claim:
An apparatus for selectively closing a well conduit to enable pressure applied to the conduit to actuate a downhole tool, the apparatus comprising: a housing for connection into a conduit disposed in a well and having a bore disposed longitudinally therein; a seat disposed within the bore, the seat having a non-dissolvable expandable member having a retracted position and an expanded position; at least one dissolvable material operatively associated with the non-dissolvable expandable member such that the at least one dissolvable material maintains the non-dissolvable expandable member in the retracted position prior to dissolution; and a plug element adapted to be disposed into the conduit, the plug element landing on the seat and blocking fluid flow through the conduit when the non-dissolvable expandable member is in the retracted position to enable fluid pressure to be applied to the conduit for actuating a well tool connected into the conduit, wherein, the movement of the non-dissolvable expandable member from the retracted position to the expanded position is facilitated by dissolution of the dissolvable material, thereby permitting the plug element to pass completely through the seat.