Turbine Casing

The casing is made of four main parts
• Bottom Half-If all the nozzles are contained in the top half, then the bottom half is subject to steam at wheel case pressure and temperature only and can therefore be made of cast iron.
  The bottom half in this case extends from end to end and contains the following listed from ford to aft
  1. Thrust bearing housing
  2. Ford Journal bearing
  3. Ahead casing proper
  4. Ahead exhasut belt
  5. (Astern casing and belt if fitted)
  6. Aft gland housing
  7. Aft Journal bearing
  8. Flexible coupling housing
  Ahead Nozzle box-Contains ahead nozzle, subjected to boiler pressure and temperature hence made from cast steel
• Turbine casing cover- Subjected to reduced pressure and temperature and can therefore be made of cast iron
• Astern Nozzle box- Seperate top covers may be supplied to allow ease of maintenance for thrust and journal bearing

LP Turbine Casing

To reduce windage losses the astern turbine exhausts in the same direction as the LP turbine. The Astern casing is located by crossed bars that are able to take the torque reaction from the fixed blading. The bar layout also allows for radial expansion as does the steam inlet which is fitted with a sliding coupling