Anhydrous Ammonia Storage Vessel Standards

[Wilkie]

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