Abstract: Apparatus for freezing liquid-carrying pipes, with an annular casing having an inwardly open cross-section, with a supply line, provided with a valve, for supplying a refrigerant to the interior of the casing, which is improved in that the casing (1) has two parts (2,3) which can be directly fixed together at right angles to the casing axis and with end walls (4,6;7,8) kept spaced by a jacket wall (9,11) and that a carbon dioxide supply lance (43) with its end face (44) having an opening can be brought up to the connecting face of the inside edges (41) of end walls (4,6;7,8).