JPS55166568A - Steam stop valve with bypass valve - Google Patents

Abstract

PURPOSE: To reduce the leakage amount of steam from a gap between a valve rod and a guide bushing therefor while a steam stop valve with a bypass valve for a steam turbine is opened.

CONSTITUTION: In case steam A enters into a gap h between a valve rod 2 and a guide bushing 13 while a valve is opened, the steam A is expanded within the first annular groove 20 and its pressure is reduced due to that there are formed at the inner surface of the bushing 13 annular grooves 20 each having larger volume than the sectional area of the gap h. The steam passing through the first annular groove is successively expanded within the subsequent annular grooves 20 and its pressure is reduced more and more, so that the leaked amount of the steam emerging to the down stream of a main valve 1 becomes null or extremely low level. In addition although the steam pressure is applied on the flanged portion of the bushing 13 upon the entering of the steam into the gap h, the bushing 13 is fixedly supported by means of a slipping out preventer 23 latched to the main valve 1 via a pawl 23a so that the bushing will not come out from the main valve 1.

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