You can get a 6000 psi, 2”NPT ball valve from McMaster-Carr... actually cheaper than I thought it would be:
Like a lot of the others chiming in here, I’m wondering what your application is?!?
It sounds like you’re trying to make some big-port accumulators, I’m guessing high pressure air from your questions. That being said, still interested in what your purpose is...
I do motion picture special effects and this sounds like what we often use for pneumatic car cannons or accelerators... I’m sure there are other industries that may have use for a lightweight air accumulator with a massive port, but I don’t know of any.
Parker-Hannifin, as well as most hydraulic accumulator manufacturers can easily supply what you’re looking for... but I’ve never seen a hydraulic or pneumatic accumulator made from carbon fiber. Typically weight isn’t such a concern in those applications. But basically the pneumatic setup is simply a bladder accumulator sans bladder.
Dan Sudick has rack of high-pressure accumulators to store pressure for his BIG ratchet... For the non-movie folk out there, a ratchet is an accelerator. Think of the previous generation aircraft carrier catapults, powered by compressed gas instead of steam. Basically a hydraulic cylinder with some combination of pulleys to compound the rods stroke. Sudick’s big ratchet MASSIVE. Something like a 12” bore, 25-foot stroke cylinder with three BIG ports on the rod side. If memory serves that device can be compounded four times for a total pull of 125’, give or take.
JD Schwalm opened the ports on aluminum dive tanks to 1” ORB/SAE fittings. However, after doing hydrostatic testing he limits those accumulators to 2000psi.
I’ve worked with other guys who just use hydraulic hose for accumulation. Again, I’m not certain of the max pressures, but you could looking into a length of -32, or -48 hydraulic hose.
In any case, I’m just speculating as I don’t know what your end goal is. I will shy you away from using NPT fittings and recommend fittings of the SAE flavor. Especially if, I’m assuming here, mobility is part of your equation and that’s why weight is a concern. Mr. Murphy LOVES tapered fittings... they prove his law every time... it’s guaranteed that you’ll never get the fitting clock you need AND the seal you need at the same time with tapered fittings. Clocking SAE fittings is always easier. O-Ring boss, flange or face seal fittings are all available in the size you want up to -64 sizes I believe??? Hose as well. Above that you have to hard pipe with flange fittings if memory serves.
Again, not fully understanding your application, I’m having to make assumptions.
Jeremy