Sink Drain/Trap/SJ Detail Questions

[wwhitney]

Hello,

I've got six sinks to finish in a whole house remodel, and I have a few questions on some of the details.

1) Delta 33W576 drain assembly comes with a white foam gasket to use on the top side of the sink. It seems quite compressible and would probably squeeze down to be nearly invisible. Is this a quality choice, or is traditional plumber's putty a better option?

2) On a slip joint connection, what is the minimum acceptable engagement? Just full engagement of the SJ washer on the pipe, or 1/8" further than that, or? Basically the threshold for putting in an extension.

3) Likewise, is there a maximum engagement? With a bell end (like on a trap), that obviously determines it for like size tubes. But a 1-1/4" tailpiece with reducing SJ washer could go into a 1-1/2" trap farther than the bell end length, is that OK, or better to cut the tailpiece?

4) For conical SJ washers, any preference between black rubber and white polypropylene?

5) For a 1-1/2" ABS trap adapter, is there an option to directly connect a 1-1/4" tubular trap arm, i.e. a 1-1/2" IPS x 1-1/4" tubular trap adapter nut? Or would one need to use a 1-1/2" FIP x 1-1/4" MIP adapter plus a 1-1/4" trap adapter nut, like this one: https://www.brasscraft.com/product/1-14-in-o-d-tube-x-1-12-in-fip/

Cheers, Wayne

 

[James Henry]

1. I've never used it but it's probably been tested and I would give it shot.
2. The further you can insert it the better.
3. See 2.
4. white, the rubber one dry rot and crumble.
5. Most traps come with a reducing washer or you can purchase them separately. I've used them many times. Just use an 1-1/2" x 1-1/4" reducing nut if you can, it makes a nicer seal.

https://www.lowes.com/pd/Keeney-Pol...V4imzAB29YQ-BEAQYASABEgJ___D_BwE&gclsrc=aw.ds

 

[Sponsor]

 

[Reach4]

2) On a slip joint connection, what is the minimum acceptable engagement? Just full engagement of the SJ washer on the pipe, or 1/8" further than that, or? Basically the threshold for putting in an extension.

I think fully engaged is enough. I doubt that this will come up.

The tailpiece may be taking some of the weight as you adjust your trap arm pitch.

3) Likewise, is there a maximum engagement? With a bell end (like on a trap), that obviously determines it for like size tubes. But a 1-1/4" tailpiece with reducing SJ washer could go into a 1-1/2" trap farther than the bell end length, is that OK, or better to cut the tailpiece?

Not so far as it makes it into where the santee turns down.

For a 1-1/2" ABS trap adapter, is there an option to directly connect a 1-1/4" tubular trap arm, i.e. a 1-1/2" IPS x 1-1/4" tubular trap adapter nut? Or would one need to use a 1-1/2" FIP x 1-1/4" MIP adapter plus a 1-1/4" trap adapter nut, like this one: https://www.brasscraft.com/product/1-14-in-o-d-tube-x-1-12-in-fip/

Use the search term trap reducing washer on your store's website. I understand that you had used that term. Some come with nuts. Some nuts are made to work without separate washers, so if your trap adapter has that, you will be discarding that nut to use 1-1/4.

Going for white polypropylene or 17ga brass?

I don't have much washer experiences. The green ones worked for me. But buying two kinds sounds like a good alternate strategy to save a trip to the store.

 

[wwhitney]

James, thanks for your responses.

2) Sure, but sometimes things are on the short side, and you have to decide whether to add a straight extension with another SJ connection. So the question is, what is threshold for needing an extension? Seems clear to me if the pipe doesn't fully engage the washer, you need an extension. But is full engagement enough (the end of the incoming pipe just reaches the downstream edge of the washer)?

[Yes, this is coming up for me in one sink, where the trap arm has to exit out the side, farther back than the U-bend on the trap can reach, so I'm use a Pasco Freedom Arm. Which I wish were an inch longer. I do have control over where I put the trap adapter, but I'd prefer to have it covered by the box escutcheon. Maybe I should try to find an extra long box escutcheon, then I wouldn't need to worry about this.]

5) So I just tried the following, which I think is what you're suggesting: I have a 1-1/2" ABS trap adapter (which comes with a single piece nut/washer), and a nut from a 1-1/2" trap, and a 1-1/2" x 1-1/4" SJ reducing washer from the trap. I was surprised to find the trap nut fit the trap adapter, I hadn't realized they were both IPS. So I was able to put the 1-1/2" x 1-1/4" SJ reducing washer under the 1-1/2" nut and screw it onto to the threaded portion of the ABS trap adapter. That should make a sound SJ connection?

BTW, that makes me curious, would the same thing work with a standard 1-1/2" brass nipple? Or does the trap adapter have a special end to accept the conical surface of the SJ washer that a plain nipple doesn't?

Cheers, Wayne

 

[wwhitney]

Going for white polypropylene or 17ga brass?

I went with chromed 17ga brass on the idea that it looks better. Not sure it was worth it, as the sinks all have base cabinets. It would be easier to leave some of the black Schedule 40 exposed, so that the trap adapter doesn't have to be so close to the wall to fit under a box escutcheon. With black polypropylene everything would be black. [Except the ABS trap adapter came with white translucent nut/washer combos, I'd have to find black replacements for those.]

Cheers, Wayne

 

[James Henry]

2). You are guaranteed to have a leak unless the washer is on the end of the pipe at the very least 1". When you have the maximum amount of drain pipe inserted, the whole drain becomes one solid piece and durable.
A tail piece extension inserted on the trap arm is better than a loose connection but with an offset trap arm your hands might be tied.
I like the 1-1/2" x 1-1/4" slip nut because it makes a tighter and neater seal.
The trap adapter threads are the same as on a nipple the difference is that the trap adapter is designed to accept a slip joint washer and theirs no way to tighten a close nipple with out damaging the threads.

https://www.plumbmaster.com/plumbma...MIzKD5w5vK7wIVso1bCh1v5QSzEAQYBCABEgLyHvD_BwE

 

[wwhitney]

The trap adapter threads are the same as on a nipple the difference is that the trap adapter is designed to accept a slip joint washer and theirs no way to tighten a close nipple with out damaging the threads.

Thanks again. One thing I'm still not clear on--are you saying it would be OK with a longer nipple with undamaged threads, or would it still be prone to leaking, because the end of a regular nipple isn't milled the same as a trap adapter. I guess the trap adapter has an internal bevel to mate with the conical SJ washer?

Cheers, Wayne

 

[James Henry]

Not every nipple is exactly the same, I would inspect a few of them until you find one that has a decent inside bevel. The slip washer will most likely compress enough so as not to leak, add a dab of pipe dope on the washer for good measure. I have never had any luck finding an extra deep escutcheon, I would look for one to go around the nipple and call it good. Normally I would have used the original trap arm and added a tail piece extension, they hold up if their not to long.