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, when the sealing device is engaged with the free end of a generally tubular object , surrounds the free end of the generally tubular object , or a protrusion which, when the sealing device is engaged with the free end of the generally tubular object , is 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 lie 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 ; a grip drive arrangement (14, 16; 63, 66, 120, 132, 145, 153, 167, 188) 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 ; and a stop member , arranged so that, when the sealing device is engaged with the free end of the generally tubular object , the stop member arrests relative motion of the generally tubular object with respect to the sleeve or the protrusion of the sealing device , and when the grip drive arrangement (14, 16; 63, 66, 120, 132, 145, 153, 167, 188) is operated to drive the grip arrangement radially towards the surface of the generally tubular object , the stop member allows further relative movement of the generally tubular object with respect to the sleeve or the protrusion of the sealing device . a main body comprising either a sleeve which, when the sealing device is engaged with the free end of a generally tubular object , surrounds the free end of the generally tubular object , or a protrusion which, when the sealing device is engaged with the free end of the generally tubular object , is 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 lie 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 ; a grip drive arrangement (14, 16; 63, 66, 120, 132, 145, 153, 167, 188) 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 ; and a stop member , arranged so that, when the sealing device is engaged with the free end of the generally tubular object , the stop member arrests relative motion of the generally tubular object with respect to the sleeve or the protrusion of the sealing device , and when the grip drive arrangement (14, 16; 63, 66, 120, 132, 145, 153, 167, 188) is operated to drive the grip arrangement radially towards the surface of the generally tubular object , the stop member allows further relative movement of the generally tubular object with respect to the sleeve or the protrusion of the sealing device . <EOS>