NFPA-13 indicated the following:
18.104.22.168 Dry Pipe Underground, Where necessary to place pipe that will be under air pressure, underground, the pipe shall be protected against corrosion.
22.214.171.124.2 Unprotected cast-iron or ductile-iron pipe shall be permitted where the joined a gasket joint listed for air service underground.
Also the fire piping shall be monitor and accessible .
Would it possible to install large part of sprinkler / fire stand piping underground.?
Can you please verify the possibility and recommended pipe material for these application?