Steam introducing part structure of steam turbine

Claim 1

A steam introducing part structure of a steam turbine having a rotor with first stage moving blades, comprising: an outer casing with a main steam inlet; an inner casing disposed in and separate from said outer casing; a 180 degree nozzle box disposed in and separate from said inner casing and having a chest and nozzles which are formed in an arc of about 180 degrees in said chest and face the first stage moving blades of the rotor, said 180 degree nozzle box being secured to said inner casing about a horizontal abutment face thereof; a steam introducing pipe provided between the outer casing and nozzle box and passing through said inner casing for introducing main steam from said main steam inlet of said outer casing into said nozzle box; said steam introducing pipe having a flange about the middle portion, and being separate from and independent of each of said inner and outer casings and said nozzle box, said flange of said steam introducing pipe being provided with a plurality of through holes arranged circumferentially; said steam introducing pipe being airtightly secured to said inner casing by fastening said flange on said inner casing with bolts, screwed in threaded holes provided in said inner casing at the positions corresponding to said through holes through said through holes of said flange; one end portion of said steam introducing pipe being airtightly and slidably inserted in a hole formed in said outer casing at the main steam inlet portion through a seal ring, and the other end portion being inserted in a steam inlet of said nozzle box through a seal ring, for providing expansion of respective ends of said steam introducing pipe relative to said outer casing and said nozzle box so that the main steam from said main steam inlet is introduced into said nozzle box.