Plumbing: Old Holding Tanks, Pipes & Valves

[Doggie]

I have a 1981 Foretravel and need to replace the Thetford waste valves with the "new" style. The biggest problem is the 3" ABS pipes which fit into the tanks have O rings. There is a clamp on the tank outlet which apparently secures the pipe with the O ring.
My questions are:
1. Is 3" piping with a groove for an O ring available?
2. If so, where can they be found?
3. Is there some king of glue or sealer used in conjunction with this O ring system?
Any insight into this job is appreciated.

[Doggie]

I have a 1981 Foretravel and need to replace the Thetford waste valves with the "new" style. The biggest problem is the 3" ABS pipes which fit into the tanks have O rings. There is a clamp on the tank outlet which apparently secures the pipe with the O ring.
My questions are:
1. Is 3" piping with a groove for an O ring available?
2. If so, where can they be found?
3. Is there some king of glue or sealer used in conjunction with this O ring system?
Any insight into this job is appreciated.

[Wallaby Dan]

Most of the RV shops should have or can point you in the right direction. Good luck with your new home on wheels!!

[RedneckExpress]

If you have enough ABS pipe coming from the tank, you can hack off the end and fit it with the needed fittings to convert it to the newer dump valves. As to the pipe's fitting into the tank, the newer rigs use threaded fittings. I have the older clamp style on my black tank which has cracked through in a number of locations from age and vibration. I sealed it up by using a couple tubes of plumbers Epoxy Putty. Tank hasn't leaked since.

[Doggie]

Thanks Joe. I was able to cut out the old Thetford valves and replace them with the new style using the existing pipe ends and a bunch of hub reducers. I also used a rubber coupling to compensate for the difference in length created by the cobble job. I put new O rings on the pipe ends and I should be good to go. Your tip about the plumber's epoxy is well received because at some point -- hopefully not now -- I may need to do that.

[RedneckExpress]

Yours may be in better condition than mine as mine hangs exposed from the underside of the camper's overhang, so it gets hit by some of the spray that washed up going down the road.

Those rubber couplings have been used by a fair number of people to compensate for when a pipe cracked off. It gives the line a greater ability to flex between the dump pipe and the tank.

[Doggie]

Yes Joe, I had an alignment problem before I cut a pipe and added the rubber coupling. I also had a couple leaky joints (probably didn't use enough cement) but was able to seal them around the outside with numerous coats of ABS cement. It was a dirty and difficult job that took a lot of time but I now have the new style valves that will be a cinch to replace -- and no leaks. I also added a couple more pipe supports that should make for less wear and tear on the old holding tanks.