An assembly for a multistage turbine of a turbomachine has a static sealing device and a nozzle with a radially outer end and an outer casing surrounding the nozzle. The static sealing device is arranged radially between a radially outer end of the nozzle and the outer casing. The static sealing device includes an annular seal borne by the nozzle and an annular structure that defines a plurality of radial annular walls. The walls are axially spaced apart from one another, and at least one first wall is in annular contact radially inwardly with the annular seal. A longitudinal dimension of the annular contact is less than a longitudinal dimension of the seal.