Valterra fittings

[RankAm]

I am trying to dry fit the pieces of my Valterra dump assembly, and I cannot figure out how best fix my problem.

Here are the two pieces involved:
1. On top, a female NPT fitting (that will be attached to the bottom of the black tank sitting on the floor of the coach)
2. On bottom, male Threaded Flange (that will attach to the rest of the Valterra assembly in the belly pan)


The male threads on the flange end up tightening before fully seating into the female fitting. The result is that the connection of the two pieces causes a wide gap between the upper piece and the top of the Valterra dump assembly. As a result, either:
1. The Valterra assembly hangs too low into the belly pan, which will mess up the alignment with the piping coming into the Valterra (see here) or
2. I will have to raise the black tank off the floor of the coach, and I would prefer not to do that because the top of the toilet already is high).

Would it be possible to cut off some of the threading on the male threaded flange?

I am thinking that I could mount the flange onto a block of wood for stability and then use my bandsaw to cut off part of the male threading so that I get a tighter fit. Doable? Sensible?
Any guidance would be appreciated.

Hank

[55AS]

No answers :-(
What did you decide to do?

[RankAm]

Originally Posted by BambiTex

No answers :-(
What did you decide to do?

BambiTex:

I have not been able to work on this, so I have not made a decision (or tried anything).

I see that Melody Ranch (here) suggests that you may have an alignment issue regarding your leak problem.

Hank

[55AS]

Thanks.
Alignment is not the problem. Leak is coming from underside of black tank.
Bolt heads used to connect valve to threaded male fitting are hitting underside of floor prior to full engagement of all threads into female fitting under tank. Leaking at threads in spite of teflon tape.

[RankAm]

Originally Posted by BambiTex

Thanks.
Alignment is not the problem. Leak is coming from underside of black tank.
Bolt heads used to connect valve to threaded male fitting are hitting underside of floor prior to full engagement of all threads into female fitting under tank. Leaking at threads in spite of teflon tape.

Could you recess the bolt heads partway into the floor (would that give you enough depth to fully seat the bolts)?

[55AS]

I spent a couple hours on this last night. Tried super duper "blue" pipe tape to no avail. Finally disassembled bathroom by removing toilet, toilet support, vent pipe and black tank. Reassembled male flange and female tank fitting on workbench and discovered that they never fully mate up, either with or without tape and the connection leaks. VTS is assisting as we try to find a solution. Any ideas?

[RankAm]

Originally Posted by BambiTex

I spent a couple hours on this last night. Tried super duper "blue" pipe tape to no avail. Finally disassembled bathroom by removing toilet, toilet support, vent pipe and black tank. Reassembled male flange and female tank fitting on workbench and discovered that they never fully mate up, either with or without tape and the connection leaks. VTS is assisting as we try to find a solution. Any ideas?

Thanks for your experiment, which confirms what I expected: the two parts do not snug up.
I am back where I started. I either have to raise my tank (and toilet) or try to cut off some of the threading on the male threaded flange.
Hank

[55AS]

After consultation with VTS I have decided to change to solvent welded fittings. No leaks but harder to disassemble in the future.

[55AS]

Got my new parts. Planning to assemble tonite.

[dbj216]

Good deal. I bet it won't leak when done. Good riddance pipe threads.

David

[Alumineer]

Originally Posted by dbj216

Good deal. I bet it won't leak when done. Good riddance pipe threads.

David

That's the problem with pipe threads... they are tapered so you can't really pre-determine how much standoff room you will need between the two pieces. Even cutting off part of the male fitting does not guarantee that you will reduce the standoff room because the fit gets tighter as you get closer to the flange of each part.

The only thing you can try is lubrication (teflon pipe sealant is good) and even teflon tape will help but only a little. Oftentimes the fitting has to be much tighter than you think is reasonable in order for it to seal.

[55AS]

So the story has a happy ending. Solvent welded fittings went together easily and, as expected, are 100% leak free! Now let's hope I never need to get at the underside of the black tank :-)

[dbj216]

Yea! Clap, clap, clap.

Now on to the next item on the list.

David

[RankAm]

BambiTex, I am glad to know that you have a good solution for your situation. I have been working on gray tanks, and I have not made a decision on what to do for the Valterra on my coach.