Ozguristan,
If you can apply the same loads and load cases used in the analysis of boiler piping, you are able to use displacements at the terminal point for the turbine piping analysis. However, you need to iterate your analysis until the forces and moment at the terminal point reach close to the forces and moments which were given at the terminal point of the boiler piping. Watch signs, the moments and forces have to be with opposite signs of given. This can apply for the new piping.
If you are trying to analyze existing piping this may still work. In case you can not find the same forces and moments you need to think about what is causing that. You can find infinite reasons for that. Your job is to screen them and find the possible cause with the information available or the required information may not be available and you need to ask for them.
In case the terminal point is very close to the outlet header of superheater/reheater of the boiler, I suggest you to include the header and its supports into the analysis. Some cases the support of the header can be the SH/RH tube bank support on the walls. Some cases the wall to wall line might have more than one header; this becomes a bit more complicated if you are not familiar with boiler design.
Including the boiler piping into your analysis can make your analysis more complicated due to the determination of neutral thermal lines or elevation on the header side and introduced thermal expansions onto the header by the boiler bank in case HRSGs are concern. Conventional boilers are a bit more complicated than this.
In case the header of boiler SH/RH includes risers from the SH/RH the analysis may become more complex.
If you can attach one or two cross section of boiler piping we may be able to give you better guidance on boiler side if you need.
You can write me on the following address if you need to discuss:
demir@bigpond.net.au
Kind regards,
Ibrahim Demir
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Peace at Home, Peace in the World.
M.K. Ataturk