Method and device for machining a sealing seat of a shut-off valve

A method of machining a sealing seat, arranged at an end of a connection pipe, of a shut-off valve mounted in a power plant or an industrial plant, the method which comprises the following steps:

• a) removing a valve upper part of the shut-off valve and housing fittings from a housing of the shut-off valve, to thereby expose a housing orifice;
• b) introducing a bracing fixture with a counter-bearing through the housing orifice into the connection pipe or a further connection pipe and fastening the fixture to an inner wall thereof;
• c) introducing a machine tool with a bearing through the housing orifice into the housing and affixing the bearing to the counter-bearing;
• d) machining the sealing seat with the machine tool;
• e) releasing the machine tool from the counter-bearing and removing the machine tool through the housing orifice;
• f) optionally repeating steps c) to e), if required, with a further machine tool or with the same machine tool;
• g) releasing the fixture from the connection pipe and removing the fixture through the housing orifice;
• and
• h) attaching the valve upper part and the fittings to the housing.