JIC, ORB and face seal are prevalent in larger and higher spec machines. NPT prevails where the market is populated by customers buying on price point as their number one criteria. Every bargain style retailer of hydraulic components will showcase NPT hoses & fittings.
Yep. You hit all those nails on the head. The shame of it all, is that any one of those could become the standard, if we weren't so resistant to change. "what we've always done" is the status quo everywhere. That those standards are replacing NPT around the world doesn't seem to register here in the states for some reason. Heck, I have used them, and I couldn't come up with the standards designations (been a couple years). You present JIC or ORB most places in America and you'll get blank stares....
Not bagging on the USA, but as an engineer I see this kind of myopic design everywhere. Heck, even I have defaulted to NPT on the hydraulics of the product I work on, because that's what the company "has always done". NPT is such a pain when you need to clock fittings a certain way. If I was to redesign our little hydraulic bulkhead panel with these fittings, I could eliminate about $100 worth of quick connects, that aren't just there for saving time on assembly, they are there to provide a swivel between the hydraulic power unit and the system. Yes, I'm aware that there are swivel fittings. But again, instead of designing hoses with the swivel built in, we're using NPT by default, and then adding the swivels as an additional fitting where we need it.
Take a look, at the crappy surface finish on NPT parts coming from China and you'll know why it takes so much work to seal them.
In theory, the seal relies on an "interference fit" after all, we're basically driving in a mechanical "wedge". The better the surface finish and tolerance of the thread form, and the "farther" you can drive in this "wedge" given the same amount of torque from your wrench. Teflon tape doesn't just seal, it also lubricates so you can get drive the fitting in further. Same for pipe dope I guess, though it's primary use is as a sealant, it does lube the threads.
I've had cheap pipe fittings of steel and brass the past few years that I could barely hand assemble at all. Burrs, incomplete machining, obvious tool chatter..... Sheesh.
Compare that with my job of a few years ago doing cleanroom equipment - all stainless fittings for gas/air/water systems, made in the US or japan, perfect thread finishes and just a little teflon tape and a good seal. And using the ORB fittings with fine thread pipe fittings, and being able to clock an elbow anywhere you want? That's awesome.
