recently I read a job design specification for pipinig stress . this specification said that "As a general rule the friction forces acting on the base plate of in/out-lines of rotating equipment shall be considered along with momentum and thermal forces in the nozzle. For these equipment,when horizontal movements are less than 5mm and sliding plates are provided, friction loads can be excluded in the evaluation of loads in mechanical equipment nozzles."
I want to know other engineer how to deal with the friction loads in rotating equipment nozzles? if there is a spring support?

Who knows it will be useful for you.
http://www.pipestress.com/pages/pepapers.html

Another case, I have ever had a model with friction 0.3. Set up load cases and duplicate the load cases required for load check and set 0 multiplier friction at static load cases. Then I checked for both. I realize not all come 0 friction in reality. I think it is a conservative approach. Pls advice..

I also think your method is conservative.for example ,the pipe to the centrifugal compressor is 1000mm outside diameter. it's
hardly to meet API 617 with 0.3 multiplier friction