Importance

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Abstract

In a turbine inclusive of: a turbine shaft having a longitudinal axis, a steam pipe, a casing circumadjacent the pipe, the pipe and casing being shiftable in vertical and transverse and axial directions relative to the longitudinal axis of the shaft, and a seal assembly disposed between the pipe and casing and comprising a stack of interdigitated relatively large and small piston rings, each large ring loosely fitting inside the shell during nonoperative conditions and having teeth firmly and sealingly engaging the casing during operative conditions; and having a coefficient of thermal expansion greater than that of the casing for expanding at a rate faster than the expansion rate of the casing under a condition of increased temperature, each small ring loosely fitting around the pipe during nonoperative conditions and having teeth firmly and sealingly engaging the pipe during operative conditions; and having a coefficient of thermal expansion less than that of the pipe for expanding at a rate slower than the expansion rate of the pipe under a condition of increased temperature, with the large and small rings tightening upon the respective casing and pipe respectively under an increasing temperature condition and shrinking from the respective shell and pipe respectively under a decreasing temperature condition, and the teeth of the rings deforming to create a complete seal.

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First Claim