2.8   Crossover pipework

 

The steam from the intermediate pressure cylinder passes to the low pressure cylinders through large diameter IP/LP crossover pipes, which have to accommodate the thermal expansion between cylinders by a combination of various designs of bellows which allow either bending or axial movement.

The bellows arrangements either incorporate hinge links or have tie rods in order to transmit the pressure forces in the pipe, thus protecting the bellows convolutions from the tendency to open out. Any bellows units at the horizontal ends of the crossover pipes are usually of the balanced type, incorporating tie rods. A typical arrangement of this piping which includes both types of bellows is shown in Fig 2.40.

IP/LP crossover pipework

On some designs of 500 MW machine, these pipes are run along the sides or underneath the machine.

Some early 660 MW machines with pannier condensers used both crossover pipes and cross-under pipes. Similar bellows arrangements were used to accommodate thermal expansion.

 

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