Air Tank Drain Valve Leaking

[farmer52]

Each week I start the MH to charge the batteries and move it. After shutdown I always drain the moisture from the air tanks. Well today after I pulled the cable on the LH tank and released the cable, I could hear air continue to leak. I pulled and released the cable several times thinking the drain valve was either sticking or a piece of dirt was keeping the valve from seating. No luck. I looked at the valve and it is rusty. I got my can of PB Blaster and sprayed on the threads. Bubbles formed around the threads. Maybe that is why my air is leaking down so fast (but I previously never heard an air leak).

Some questions:

1. Can PB Blaster be used to free pipe fittings?

2. Are the tank threads rusted and need a new tank too?

3. If the valve breaks off, do they make an "easy out" for pipe threads?

[Truckinjeff]

The valve threads are NPT threads, the threads have a taper to them that probably won't allow penetrating lubricant to soak through under normal circumstances. But if it leaking from around the threads this may mean that the valve is loose and will unscrew and tighten up with ease or there is a crack in the threads which may break off if you try to unscrew it. You'll have to put a wrench on it and see if it moves. Usually the threads in the tank don't usually rust if you maintain your air system properly, but if they are rusted you can use a pipe tap to clean them up. Yes you can easy out the pipe threads if it breaks off.

[farmer52]

Thanks for the reply.

After giving it some thought, pipe threads are "self sealing" so a penetrant would likely not work. As for the easy out, a standard one will work since it relies on a straight hole to grip the inside of the treaded fitting. I am going to try some heat on the valve before I wrench on it. If I get it out I may need to chase the threads with a 1/4" pipe tap.

[rsb502]

Uh, yep!

[farmer52]

Replaced the drain valve on Saturday. I applied some heat (propane torch) to the threaded area. I used my 2' adjustable wrench (didn't have a 1-1/16" open end and too lazy to cut the cable to use a box end but had my pipe wrench handy). I applied a little muscle and I was surprised, the valve came loose without any problem. Installed the new valve. Next week I am going to replace the two (2) valves in the RH tank. Also plan to replace the TT valve and install new lines and gladhands. Off to Tittsburgh this morning for a week long conference.