The invention relates to a valve that comprises: a base body (10) defining a flow section (22) for a fluid; a stopper member (12) rotatingly mobile relative to the base body (10) about a rotation axis (X-X) between a fluid passage position and a flow-section blocking position; a shaft (14) for actuating the stopper member (12) extending through the base body (10); sealing means provided between the actuation shaft (14) and the base body (10). The sealing means include a mechanical lining (16). The invention can be used for inlet valves in turbines.