A sealing device for sealing a free end of a generally tubular object, the sealing device comprising: a main body comprising either a sleeve which may, when the sealing device is engaged with the free end of a generally tubular object, surround the free end of the generally tubular object, or a protrusion which may, when the sealing device is engaged with the free end of the generally tubular object, be inserted into the interior of the free end of the generally tubular object; a grip arrangement which is connected to or supported by the main body, and positioned to be against or adjacent a surface of the generally tubular object when the sealing device is engaged with the free end of the generally tubular object, wherein the grip arrangement is radially moveable with respect to a central axis of the main body; and a grip drive arrangement operable to drive the grip arrangement radially with respect to the central axis of the main body, towards the surface of the generally tubular object.