Abstract: An apparatus for pipeline isolation comprising a pipeline isolation tool (1) having a cylindrical vessel with locking grips (21) and sealing member (19) encircling the cylindrical vessel. The locking grips (21) and sealing members (19) are operable by a hydraulic piston (10) contained within a core of the cylindrical vessel and a hydraulic pump for operating the piston (10). The piston (10) is a double rodded acting piston (10) comprising an elongated shaft and a head centrally located on the shaft so that the volume swept by the piston (10) is equal in both directions. A control module (32) is connected to the isolation tool (1) at one end and a gauging tool (33) is connected to the other end of the isolation tool (1).