ansi 9standards0 code issues - anhydrous ammonia storage

huangyhg

ansi anhydrous ammonia storage
cga g-2.1 section 5.5.6 specifies that an opening in an anhydrous ammonia "container" need not be equipped with an excess-flow valve if the opening is not larger than a no. 54 drill size.
i interpret this to mean the vessel nozzle must be restricted to this size internal opening, rather than simply inserting a #54 orifice plate in piping downstream of the nozzle.
can anyone tell me how this is interpreted by the cga or ansi  ?
thanks,
steve