Partly melting rotating helical ring assembly

A partly melting rotating helical seal assembly ensuring sealing with respect to fluids along a rotating shaft extending through a wall forming a chamber containing a fluid medium kept under pressure, said assembly comprising:

• an outer metallic sleeve fixed relative to said wall, surrounding the rotating shaft and spaced radially therefrom a certain distance and having threads on its inner surface facing said shaft and having a radially inwardly extending flange at the end of said threads remote from said chamber, said flange terminating radially beyond said threads and forming seal means with said shaft relative to said fluid medium;
• parallel threads having a depth of less than half a millimeter, cut in the shaft opposite the metallic sleeve;
• cooling means for said metallic sleeve;
• an intermediate sleeve arranged between the metallic sleeve and the threaded part of the shaft and being formed of a substance compatible with the fluid medium contained in the chamber, and cooled by said cooling means and frozen such that said intermediate sleeve is entirely solid and threaded to the outer sleeve and the intermediate sleeve when the shaft is motionless but capable of melting at its peripheral interface with the rotary shaft by the friction generated during rotation of the shaft;
• and
• wherein said threads, within said shaft form a corresponding threaded liquid interface of said intermediate sleeve during shaft rotation to prevent said pressure fluid medium from escaping from said chamber along said shaft during its rotation.