an apparatus and a method for sealing a conduit . the apparatus includes a housing , a tube for reciprocably extending through the housing bore , a rod reciprocably extending through the tube , a seal assembly associated with the tube and the rod , wherein the seal assembly includes at least one seal element which expands radially in response to an axial setting force , a proximal collar associated with the tube for engaging with a proximal end of the seal assembly , and a distal collar associated with the rod for engaging with a distal end of the seal assembly , wherein moving the rod axially relative to the tube in a proximal direction results in the axial setting force being applied to the seal assembly . the method includes using the apparatus to perform maintenance or repair on the conduit or its associated fittings .