Corrosion resistant piping

[Cris-w]

hi everyone
I am designing a fire extinguishing system. OE requires that all galvanized pipes must be painted with anti-corrosion paint. Are there any relevant requirements for this from NFPA or ASTM? At the same time, I would like to ask, is there a maximum size limit for grooved pipe fittings or threaded pipe fittings? Because I saw that some projects use grooves for pipes of DN65 and above, and threads for pipes below DN65.
THANKS

 

[TravisMack]

Grooved piping is available down to 1" (DN25) in size currently. That is an old spec where pipes 2" (DN50) and smaller were threaded and 2½" (DN65) and larger were grooved. There are no requirements for painting of pipe in NFPA 13 that I am aware of.

 

[mk3223]

The anti-corrosion paint may be needed due to the specific environmental or maintenance reasons as OE requests. isn't it?