3.7   Pipework


s the de-aerator is in an elevated position relative to the turbine, the bled-steam line has to rise at least 20 to 30 m above the bleed point on the turbine and so great care has to be taken to drain all points where condensate could accumulate.

Drain pots are provided at each natural drainage point, with a side take-off which is led with a continuous fall to a suitable low pressure disposal point. The drainage is controlled by orifices or traps, with by-passes to allow for cold start conditions when drainage requirements are at their maximum. The steam traps, if used, are set so that they discharge a few degrees above saturation temĀ¬perature to prevent condensate build-up. Attention is also given to those sections of pipe which are isolated by the action of the protection valves, to check that they have adequate drainage and so ensure that there are no trapped pockets of water which can be swept forward on opening of the valves.


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