Turbine casings

850,186. Turbine casings. NAPIER & SON Ltd., D. Aug. 28, 1958 [Jan. 14, 1957], No. 18902/57. Class 110 (3). In a casing 16 for a multi-stage turbine comprising a metal body of circular cross-section extending with longitudinal continuity of metal over the part surrounding at least two rows of stator blades 12 interposed between rows of rotor blades 11, the stator blades are rigidly secured to stator blade-rings 13, secured against circumferential movement by dogs provided on the inner edges of radially inwardly facing flanges 19, 20 in the casing, these dogs engaging corresponding radially outwardly facing dogs around the peripheries of the stator blade rings. The blade rings 13 have flanges 24 engaging circumferential seatings to provide positive axial location at the upstream ends of the rings. The casing 16 is divided longitudinally into two or more segments of arcuate cross-section which are bolted together through longitudinal flanges. Stationary arcuate shroud-plates 30 are provided close to the tips of the rotor blades 11 which plates act to locate the downstream ends of each of the stator rings 13 and these are secured in the casing by means of bolts 31. Slight clearances 32 are provided between the shroud-plates 30 and the downstream ends of the stator blade rings when cold, to allow for longitudinal thermal expansion. The casing 16 and the rotor and stator blades progressively increase in diameter towards the downstream end so that the turbine blade rings can be assembled successively from the larger diameter end.