Hydraulic fittings; JIC or O-Ring Boss?

[Delta KJ]

I'm converting the hydraulic system on my D6D SA from an "open" center type to a "closed" center type. The fittings on the original open center hydraulics that came with the D6D use JIC hydraulic fittings while the fittings on the closed center components that came from a Caterpillar AG 6 use O-ring boss hydraulic fittings. Is one better than another and when should one be used rather than the other?

[OzDozer]

Delta KJ - The o-ring fittings are a superior arrangement that provides a higher level of sealing ability .. lower damage susceptibility to variations in torque levels .. and higher levels of re-useability involving frequent connection and disconnection.
It goes without saying that the JIC fittings are cheaper to manufacture and purchase. JIC fittings are weight-saving where less weight is highly desirable.
My personal choice would be the o-ring fittings. Here's a good hydraulics website with a lot of useful technical information ..

http://www.kurthydraulics.com/threads.php

[Old Magnet]

I am not a fan of some of those "O" ring boss" fittings, especially the ones that use a jam nut and washer as back up and use them only where I have to. I also find the variety of JIC fittings to be more extensive. I make all my own hoses and buy my fittings from www.discounthydraulichose.com they have been an excellent source and I have had no problems even though the bulk of the materials are made in China.

[OzDozer]

The biggest single problem I've had with JIC fittings is the nut splitting after regular hose changes. Maybe it had a lot to do with the particular brand, and some brands are better than others .. but I always used Aeroquip fittings, and usually had a good run out of them.
The o-ring fittings require care with regard to making sure that o-ring seating areas aren't damaged or dirty .. and that you use top quality nitrile o-rings. The JIC fittings are somewhat more accommodating of mismatch and poor fit, or damage to the beveled surfaces.

[Old Magnet]

Speaking of nut splitting....that is a real problem with the pipe thread swivel nut fittings and I definitely would not recommend using any of them (although I have used a few) I have not had any problem with JIC nuts...even the China sourced units....but there are limits to how much torque any of them will handle.
I also put the thread joints together with never seize as they can become rust welded together and a problem to take apart.

[bluox]

I think you guys have o-ring boss and o-ring face seal fitting's confused?
Good luck Bob