Abstract: A gate-valve and/or hot-tap drilling system uses a secondary pack-off or sealing element which can be engaged when the primary sealing element develops a leak. Generally, the secondary sealing element is configured to have an engaged position in which a fluid tight seal is formed such that the secondary sealing element engages the bore wall in a pressure-containing housing and drill rod extending through the bore defined by the bore wall. The fluid tight seal prevents fluid flow in the annulus, if the primary seal develops a leak. When the primary seal is working normally—no fluid leak—the secondary sealing element is in a disengaged position where a fluid tight seal is not formed with the bore wall and drill rod.