A sealing device (1) for a stem (12) of a valve (10) comprising a metal gasket (4) for the valve (10) stem (12), shaped as a half “U” provided with a single sealing lip (44), which has a radially inner surface (442) and a radially outer surface (444), inclined along the radially inner direction, a wedge metal ring (6) positioned inside the half “U” of the metal gasket (4), an elastic element (7) configured to cooperate with said wedge metal ring (6), the elastic element providing the wedge metal ring with an elastic load and a static sealing ring (8). The elastic element (7) is configured for applying a force to the wedge metal ring (6) such that said wedge metal ring (6) applies a contact pressure to the sole sealing lip (44) of the metal gasket (4) shaped as a half “U”.

A sealing device (1) for a stem (12) of a valve (10) comprising a metal gasket (4) for the valve (10) stem (12), shaped as a half U provided with a single sealing lip (44), which has a radially inner surface (442) and a radially outer surface (444), inclined along the radially inner direction, a wedge metal ring (6) positioned inside the half U of the metal gasket (4), an elastic element (7) configured to cooperate with said wedge metal ring (6), the elastic element providing the wedge metal ring with an elastic load and a static sealing ring (8). The elastic element (7) is configured for applying a force to the wedge metal ring (6) such that said wedge metal ring (6) applies a contact pressure to the sole sealing lip (44) of the metal gasket (4) shaped as a half U.

An example apparatus is disclosed herein comprising a valve that includes a valve body defining a fluid passageway between an inlet and an outlet, a flow control member in the fluid passageway, a stem coupled to the flow control member, and a bonnet coupled to the valve body. The stem extends through a channel in the bonnet. A section of the channel forms a bore. The bore is threaded. The apparatus includes packing in the channel to form a seal between the bonnet and the stem. The apparatus includes a worm wheel nut threadably engaged with the bore. The stem extends through an opening in the worm wheel nut. The apparatus also includes a worm meshed with the worm wheel nut. The worm is to rotate the worm wheel nut to cause the worm wheel nut to move and adjust a load on the packing.