Master Stamping Pressure of ZSupercritical Boiler

[swapanburo]

I am designing the HP Steam Pipe from the Superheater outlet to the steam turbine of a Supercritical Power Plant. Typically this pipe is designed for the Master Stamping pressure of the Super Critical boiler (ref PG-106.3 and Fig PG-67.4 of ASME BPVC Section-1) . The Boiler supplier of the Power Plant is not yet on board.
I have estimated the superheater outlet pressure from the throttle pressure and estimated pressure drop in the pipe line. Now I want to keep some margin over the superheater outlet pressure to take care of the Master Stamping Pressure of the boiler. I am not sure how much margin should I keep. Can anyone suggest me typically how much margin is kept over Superheater outlet pressure for deciding the Master Stamping Pressure ?

Any reference document regarding this will be very helpful

Thanks,

 

[davefitz]

Per sect I PG 67.4 the MSP is the design pressure of the HP main steam outlet header when dealig with a force flow steam generator. The b31.1 power piping code has technical jurisdiction of the design of the HP main steam line to the steam turbine. See B31.1 par 122.1.2 for those rules.

The boiler designer and EPC designer may have reasons for increasing the design pressure of the HP main steam line over the minimum values implied in par 122.1.2, including providing enough margin to allow the HP bypass dump to the condenser to open before the safety valves lift.

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