Abstract: A gate valve structure has a one-piece cage (76) in the form of an open ended sleeve which fits in the valve chamber of the body. The cage includes a pair of openings (82) which are aligned with the inlet and outlet flow passages in the body. Seats (60, 62) are mounted within the openings of the cage and have outwardly extending lugs (66) which are received within slots (88) in flanges (86) about openings (82) in the cage. The flanges (86) limit the inward movement of the seats toward the gate assembly and maintain a predetermined minimum spacing between the seats to minimize binding of the seats against the gate. The seats are easily inserted within the openings of the cage after the cage is fitted within the valve body.