L.A. Style P-Trap

[JASchneider]

Greetings. Please excuse my sloppy terminology. I have a question for anyone out there who has experience with an L.A.-style p-trap, which has the usual slip joint for the sink drain, but a radiator-vavle-type compression joint on the other side of the j-bend (that is, right in the middle of the trap water). I have a Watts chromed brass model, which I happened into when trying to figure out an odd installation of a specialty wall-hanging sink, in which the drain is very close to the wall. The appropriate solution probably would have been (and might still be) a bottle trap, but the L.A. trap happened to fit just right between my sink drain and the DWV stub out from the wall. Problem is, that compression joint tends to leak. It comes from the factory with a clear (and carcinogenic, if you read the box) sealant on the j-bend flange. Like a radiator valve or elbow, the nut has no washer of any type -- it's just supposed to be a metal-to-metal seal. I figure the only possible remedy is to clean the flange and then smear it with a good pipe sealant, tighten it carefully, and then let it set for a day before running water in the sink. But before I do that, has anyone else used one of these traps successfully, or do they just tend to leak? If they're really just problematic, I'd scrap the thing and go get a bottle trap. TIA.

(same as mine, but mine's smooth and chromed all over)

 

[Leejosepho]

... a radiator-valve-type compression joint ... tends to leak. It comes from the factory with a clear (and carcinogenic, if you read the box) sealant on the j-bend flange ... a metal-to-metal seal. I figure the only possible remedy is to clean the flange and then smear it with a good pipe sealant, tighten it carefully, and then let it set for a day before running water in the sink.

Is that a tapered flange and cup or do both pieces have flat faces? Either way, a little silicone ought to make a nice seal, and I would have the other connections loose -- not quite finger-tight -- while tightening that particular connection and letting the silicone cure.

 

[Sponsor]

 

[Cass]

You should only use pipe dope or Teflon tape on the threaded 90 portion. The rest is self sealing with a gasket / slip joint.

 

[Jimbo]

Metal-to-metal is one of the most reliable types of seals, but components must be in good condition. LA traps are widely used. We mostly use the ABS LA trap, and I never had one leak at the joint, but of course plastic is different than metal. You can use heavy paste like Great White on the joining surfaces, which might help. You have to make sure the two pieces are aligned, not cock-eyed. And on the metal ones, you have to snug it up pretty good, but not with an 18 incher!

I would not use silicone, because it will make future disassembly and reuse difficult.

 

[JASchneider]

Thanks for all the replies.

First of all, the wall stub out is PVC and that joint, with no sealant, is leak free. I'm also not surprised to hear that ABS or PVC L.A. traps don't have leakage problems, since plastics compress to some extent.

Yes, the joint I'm talking about is cupped, just like a radiator valve or elbow joint. And on my radiators, I usually have just put sealant on the cupped flange as well as the threads on the radiator nipple. I don't have leaks anymore with any of my radiators.

From all I've read, I think the answer is probably to try a viscous pipe thread sealant on the cupped flange of the j-bend (I've used Gasoila with good success, but not Great White). Although silicone could work, I guess I agree that's not the best solution.

Oh, and I know it's a good idea to tighten the compression joint first, and then the slip joint. I'll see if it works.

BTW, anyone know what that clear, carcinogenic stuff is that it comes with out of the box?

 

[hj]

stuff

Hard to tell because everything is carcinogenic in CA. They might even be referring to the brass in the trap, assuming you ever drink the water from it.

 

[Shacko]

Greetings. Please excuse my sloppy terminology. I have a question for anyone out there who has experience with an L.A.-style p-trap, which has the usual slip joint for the sink drain, but a radiator-vavle-type compression joint on the other side of the j-bend (that is, right in the middle of the trap water). I have a Watts chromed brass model, which I happened into when trying to figure out an odd installation of a specialty wall-hanging sink, in which the drain is very close to the wall. The appropriate solution probably would have been (and might still be) a bottle trap, but the L.A. trap happened to fit just right between my sink drain and the DWV stub out from the wall. Problem is, that compression joint tends to leak. It comes from the factory with a clear (and carcinogenic, if you read the box) sealant on the j-bend flange. Like a radiator valve or elbow, the nut has no washer of any type -- it's just supposed to be a metal-to-metal seal. I figure the only possible remedy is to clean the flange and then smear it with a good pipe sealant, tighten it carefully, and then let it set for a day before running water in the sink. But before I do that, has anyone else used one of these traps successfully, or do they just tend to leak? If they're really just problematic, I'd scrap the thing and go get a bottle trap. TIA.

(same as mine, but mine's smooth and chromed all over)

Don't over think! Probably millions of this kind of trap installed, just put a thin layer of pipe joint compound on the metal to metal part of the trap; you should be fine, luck.

 

[poorplmbr]

Remove the trap and look into the outlet side of the u-bend,does it have 2 little protrusions?If it does then the union portion of the trap is 2 pieces,it should be like the spud of a radiator valve.You need to remove this piece,a radiator spud wrench works fine for this but anything you can get to fit in there will work,apply some teflon tape and a bit of pipe dope,even though there probably is an "o" ring that is supposed to make the seal,reassemble the union and then reinstall the trap with some pipe dope on the male threads of the union and a little on the face of the union.That should do the trick.....

 

[JASchneider]

No, poorplmbr, what you describe isn't what I'm talking about.

I don't think I'm overthinking anything - just wanted to know if others had problems with these traps leaking and what remedies they might have tried. My second trap (sent to me for free by Watts) didn't leak when I first installed it, but then developed one. The first one just leaked. I'm going to try the viscous compound and see if that does the trick.