I don't think you would get a code reference for full port/bore but common definition would be no restriction in the piping therefore in practice you could push a pig through system for cleaning or require no pressure drop and/or flow loss. IMO your supplier is supplying reduced bore ball valve which is usually one pipe size smaller but in majority of systems is acceptable and preferred as is less bulky and cheaper.

It turns out I would be able to find some information on the port descriptions from API 608. Unfortunately my firm doesn't subscribe to API publications, it seems.

I am also of the opinion that it's not exactly full-port. These valves are also drain service valves, which leads me to think that this is sort of a non-issue.

Hello. there is no ambiguity regarding "full port ball valve". The term is defined in API, ISO, MSS, and other ball valve standards. Most contain a table giving the minimum bore size for full bore, reduced bore, and double reduced bore. API-6D, API-608, ISO 17292, and MSS SP-72 are example standards. You can also refer to any manufacturers product brochure.

For the valve supplier you have, what does their catalog say regarding the valve bore? Definitely not full port (or full bore...terms are interchangeable).

H. Different codes will sometime provide different full bore sizes. But clearly not 1.5'' for a 2'' full bore valve.
API6D and API 608 both specifie the same full bore size : 49mm (1.94 inches) for a 2'' valve, (might be a little less for class2500 and above).

ANSI/ASME B16.34 has a table A1 which shows the relationship between Valve Bore and NPS. For 2" it states the Valve Bore for ANSI 2500 Rated Valves as 1.5" API 608 states 1.94" regardless of Pressure Class whilst API 6D states 1.69" at ANSI 2500 but 1.94" For all lower classes. MSS SP72 States 'minimum bore diameters as specified in Annex A'
of ASME B16.34

Some Manufacturers on Small High Pressure Floating Ball Valves will try to match the Valve Bore to the Mating Pipe Schedule Bore, some state 'Valve Bore to suit Schedule 160 Pipe'.


The whole issue revolves around what the Pressure Class is and what Specifications the End Customer is calling up, to a degree if the Valve is Floating Ball or Trunnion Mounted.


Its always been a contentious issue and still is...

EN 1983 (it is table 4 in the 2006 issue)