Page 64 - Steam Turbines Design, Applications, and Rerating

Turbine Casing and Major Stationary Components 45

■ All diaphragms are fitted with windage shields located a short dis-
tance from the wheel outside diameter. The windage shields also
serve as additional casing protection (Fig. 2.20), plus stage moisture
removal.
■ A special arrangement of diaphragm, similar to that used on high-
temperature service, has the diaphragm halves bolted together. This
eliminates the need for upper half stops and allows for a better hori-
zontal flange casing bolt pattern, i.e., the bolt line closer to the inter-
nal pressure source, a concern in metal-to-metal applications.
The next six illustrations, Figs. 2.21 through 2.26, show various
kinds of packing (seals) used in steam turbines. Solid packing rings
incorporate a spring arrangement that pushes the packing toward the

Figure 2.22 Labyrinth seal. (Elliott Company, Jeannette, Pa.)