Just to let you know, none of the threads on the Tial MVR or MVS gates is tapered. You can thread in 1/8 NPT, but that is not the correct thread pitch, it can damage the threads, and in my case I think is the reason my gate ended up leaking. The previous owner used 1/8NPT to AN fittings on the gate and now the gate leaks where the 2 actuator halves mate, but right by the fittings. Bill is suspecting that threading the NPT fittings in too tight could have caused a small crack which is now causing the leak. And as for using thread sealant on non tapered fittings, this came from my build thread on 8th:
Quote Originally Posted by mucter
And either way, thread sealant won't help at all. Trust me, I've been there, done that. On a non tapered thread, it doesn't do jack squat. Thread sealant creates an air/liquid tight seal by being pressurized into place by the threads. Without that pressure, it won't do anything. The washers are what seal it. If that fitting won't seal with those washers, he needs to use a different fitting.