Page 339 - Subyek Teknik Mesin - Forsthoffers Best Practice Handbook for Rotating Machinery by William E Forsthoffer

Be st Practice 5 .14 Steam Turbine Best Practices

Fig 5.14.10 Single valve turbine admission path
Continued use of sentinel valves on turbine cases It is a known fact that the sentinel valves wear, leak, and
require steam turbine shutdown for repair. Most large com-
Please refer to Figure 5.14.2, Item 5. Sentinel valves were used,
years ago, as alarm devices to indicate that the steam turbine pany specifications prevent the use of sentinel valves, and re-
quire full relief-valve protection on the inlet and exhaust of all
case (low pressure part) was under excessive pressure. These
devises are not pressure relief valves and will not protect the single stage turbines. These facts are presented in
Figure 5.14.14.
case from failure during over pressure events.

Never throttle hand valves Assuring bearing housing jacket passages are open (flushed)
Hand valves should be open on main oil pump and auto-start Consulting with turbine vendor for bearing material change
steam turbines Using special high temperature service oil (synthetic based oil)

Fig 5.14.11 Single stage steam turbine hand valve Fig 5.14.13 Eliminate bearing wear and oil viscosity reduction (high
recommendations pressure service)

Sleeve bearings (usually steam inlet end) wear out quickly Removing sentinel valves
Oil viscosity is reduced and difficult to maintain Assuring that inlet and exhaust casings are protected by
properly sized and set pressure relief valves
Fig 5.14.12 High pressure single stage steam turbine bearing
problems and oil viscosity reduction Fig 5.14.14 Prevent excessive sentinel valve maintenance

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