A sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176) for sealing a free end of a generally tubular object (26, 31, 105, 112, 128, 161), the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176) comprising: a main body (3, 32, 126, 127, 150, 177) comprising either a sleeve (3, 32, 127, 177) which, when the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176) is engaged with the free end of a generally tubular object (26, 31, 105, 112, 128, 161), surrounds the free end of the generally tubular object (26, 31, 105, 112, 128, 161), or a protrusion (126, 150) which, when the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176) is engaged with the free end of the generally tubular object (26, 31, 105, 112, 128, 161), is inserted into the interior of the free end of the generally tubular object (26, 31, 105, 112, 128, 161); a grip arrangement (17, 54, 76, 115, 129, 139, 156, 163, 190) which is connected to or supported by the main body (3, 32, 126, 127, 150, 177), and positioned to lie against or adjacent a surface of the generally tubular object (26, 31, 105, 112, 128, 161) when the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176) is engaged with the free end of the generally tubular object (26, 31, 105, 112, 128, 161), wherein the grip arrangement (17, 54, 76, 115, 129, 139, 156, 163, 190) is radially moveable with respect to a central axis of the main body (3, 32, 126, 127, 150, 177); a grip drive arrangement (14, 16; 63, 66, 120, 132, 145, 153, 167, 188) operable to drive the grip arrangement (17, 54, 76, 115, 129, 139, 156, 163, 190) radially with respect to the central axis of the main body (3, 32, 126, 127, 150, 177), towards the surface of the generally tubular object (26, 31, 105, 112, 128, 161); and a stop member (109, 120), arranged so that, when the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176) is engaged with the free end of the generally tubular object (26, 31, 105, 112, 128, 161), the stop member arrests relative motion of the generally tubular object (26, 31, 105, 112, 128, 161) with respect to the sleeve (3, 32, 127, 177) or the protrusion (126, 150) of the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176), and when the grip drive arrangement (14, 16; 63, 66, 120, 132, 145, 153, 167, 188) is operated to drive the grip arrangement (17, 54, 76, 115, 129, 139, 156, 163, 190) radially towards the surface of the generally tubular object (26, 31, 105, 112, 128, 161), the stop member (109, 120) allows further relative movement of the generally tubular object (26, 31, 105, 112, 128, 161) with respect to the sleeve (3, 32, 127, 177) or the protrusion (126, 150) of the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176). a main body (3, 32, 126, 127, 150, 177) comprising either a sleeve (3, 32, 127, 177) which, when the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176) is engaged with the free end of a generally tubular object (26, 31, 105, 112, 128, 161), surrounds the free end of the generally tubular object (26, 31, 105, 112, 128, 161), or a protrusion (126, 150) which, when the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176) is engaged with the free end of the generally tubular object (26, 31, 105, 112, 128, 161), is inserted into the interior of the free end of the generally tubular object (26, 31, 105, 112, 128, 161); a grip arrangement (17, 54, 76, 115, 129, 139, 156, 163, 190) which is connected to or supported by the main body (3, 32, 126, 127, 150, 177), and positioned to lie against or adjacent a surface of the generally tubular object (26, 31, 105, 112, 128, 161) when the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176) is engaged with the free end of the generally tubular object (26, 31, 105, 112, 128, 161), wherein the grip arrangement (17, 54, 76, 115, 129, 139, 156, 163, 190) is radially moveable with respect to a central axis of the main body (3, 32, 126, 127, 150, 177); a grip drive arrangement (14, 16; 63, 66, 120, 132, 145, 153, 167, 188) operable to drive the grip arrangement (17, 54, 76, 115, 129, 139, 156, 163, 190) radially with respect to the central axis of the main body (3, 32, 126, 127, 150, 177), towards the surface of the generally tubular object (26, 31, 105, 112, 128, 161); and a stop member (109, 120), arranged so that, when the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176) is engaged with the free end of the generally tubular object (26, 31, 105, 112, 128, 161), the stop member arrests relative motion of the generally tubular object (26, 31, 105, 112, 128, 161) with respect to the sleeve (3, 32, 127, 177) or the protrusion (126, 150) of the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176), and when the grip drive arrangement (14, 16; 63, 66, 120, 132, 145, 153, 167, 188) is operated to drive the grip arrangement (17, 54, 76, 115, 129, 139, 156, 163, 190) radially towards the surface of the generally tubular object (26, 31, 105, 112, 128, 161), the stop member (109, 120) allows further relative movement of the generally tubular object (26, 31, 105, 112, 128, 161) with respect to the sleeve (3, 32, 127, 177) or the protrusion (126, 150) of the sealing device (1, 30, 74, 93, 94, 110, 123, 134, 148, 162, 176).