Questions on Unions/PVC

[Makers Marc]

Hi all,

Im trying to plumb my new 180g rimless from PA. I'm using the 16"shadow overflow and am having issues with leaking slip unions where the gasket meets the other half.

1. How perfectly flush do both sides of the union need to be before you screw them together, in order to ensure a leak free seal? What if their height is 1/4" off?

2. The leak is NOT coming from where the pvc pipe has been cemented to the union. I've also tightened them as much as I'm comfortable without cracking it. I'm also using these pvc straps with strong magnet hooks for support. They all have gaskets and I don't see anything that needs filing.
What else can I try? Vaseline?

Please help. I've spent over 20 hrs and taken 6 trips to Home Depot and want to finish this so I can move forward.

 

[TheEngineer]

Overtightening those can make them leak. Hand tight should be all you need. Take a look at the o-rings. You may have a crack in one or it might not be seated right.

 

[Makers Marc]

Overtightening those can make them leak. Hand tight should be all you need. Take a look at the o-rings. You may have a crack in one or it might not be seated right.

Thanks. I did take them all out and inspect already.

Do the unions need to be perfectly flush for them to work? Is it ok if there's a small 1/2" gap that I can push together then tighten?

Vaseline?

 

[Roy 9121]

They should be pretty straight, butt i agree with theengineer, you can over tighten them. Also, check that the o-ring is in good shape, and not torn.

 

[TheEngineer]

It shouldn’t be a problem so long as it doesn’t cause stress elsewhere. I’m not sure about Vaseline. A food safe grease might help.

 

[Roy 9121]

Thanks. I did take them all out and inspect already.

Do the unions need to be perfectly flush for them to work? Is it ok if there's a small 1/2" gap that I can push together then tighten?

Vaseline?

1/2" may be a little to much.

 

[Makers Marc]

1/2" may be a little to much.

What about height difference? I think one of mine is 1/4" higher and I lift it slightly before screwing it together.

I wish it was just a broken gasket. But this is getting tiring...

 

[Roy 9121]

What about height difference? I think one of mine is 1/4" higher and I lift it slightly before screwing it together.

I wish it was just a broken gasket. But this is getting tiring...

Optimally you want them to line up, but there should be a little play.

 

[Mandelstam]

Unplug and loosen the pipes "downstream" of the union so you're not putting stress or forcing it to be in an angle it doesn't want to be. Don't have the end plugged into the sump and then try to force it together in the middle.

 

[Makers Marc]

Unplug and loosen the pipes "downstream" of the union so you're not putting stress or forcing it to be in an angle it doesn't want to be. Don't have the end plugged into the sump and then try to force it together in the middle.

Old post but just in case someone else comes upon this.

Iever had time to come back and give you props. Once I unplugged them from the end point (sump), I was able to connect the middle joints first which eliminated the small gaps.

 

[bobman]

As long as you can screw them together without a gap on the flange you should be ok. 1 thing to watch for is the pvc cement when gluing the pipe to glue/solvent can get on the oring and the flat surface of the flange with can damage it. If the oring is bad well you will need an oring. If the flange is rough from the solvent you can take some 280-320 grit sand paper to smooth it just pay attention to make sure you sand the entire surface evenly so that is makes even contact. Also check the threads on each side the glue can bugger the threads which can make you think its tight but in reality it is not. For that you can take a file and fix the threads with a little patience.

Looking at the picture in appears the pipes with the male ends are a little to long and it is not butting up flush on the flanges if that is the case it will not seal no matter what you do. My advise would be to buy new unions and cut the pipe and install correctly