I took apart my kitchen drain since I had to replace my disposer on one side.

On the side without the disposer I took apart the flanged tailpiece that connects to the sink strainer basket with a brass nut. I thought there should have been a flat rubber or nylon washer there between the flanged tailpiece and brass nut, but there isn't. Yet it hasn't leaked in over ten years.

Is there supposed to be a flat washer there that the brass nut tightened against to make the seal, or is the tubular flanged tailpiece seals itself with the plastic flange?

There should be a washer, either a plastic one or a rubber & cloth one. (W-251 or W-251A)



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Some people substitute pipe dope for the top hat washer, which may be why you did not have one, I prefer the rubber washer over plastic

There was no washer, and the cheap metal nut was fused to the threads, and probably the rust was doing the waterproofing. I had to cut the nut and pry it loose.

steve, I got a new metal nut (made of zinc, I couldn't find a brass one), and it came with a flat rubber washer.

I installed it and it leaked. I can tell from looking down from above, the rubber washer gets pushed out of alignment when I tightened. Tried it a few times and same problem each time.

I finally got the plastic one you showed that fits over and into the tailpiece flange and that worked!



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Nuts do NOT come with the flanged gasket you needed, which is why that one leaked and you had to buy a new one since the tailpiece is plastic and the gasket is also, SOMETIMES, you can eliminate the gasket and just tighten the flange to the strainer.



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why don't they include the gasket I need instead of including one I don't need?

my strainer body is brass, and the tailpiece is tubular...but does that matter? If the tailpiece is tubular metal would that flat rubber washer have worked? I doubt it. Now that I think about it more, I think you are right in that if I tightened the brass nut enough I might have compressed the tailpiece flange enough to seal it.



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the same nut is used with any of 3 different types of gaskets

+ top-hat washer for a flanged tailpiece
+ beveled tubular washer
+ 'universal' multipurpose 'thick' flat washer (sometimes included)

they include the cheapest one (if any is included)

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638



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so the one I needed that's not included is called a "TOP HAT" washer?

Why not include all of the washers?

when I buy a 1.5" trap adapter, it comes with a 1.5" beveled washer and a 1.5"X1.25" beveled washer to allow for both sizes so it's not too far fetched to imagine a metal nut to include all that's needed.

Quote

Why not include all of the washers?

$




top hat washer: [www.bing.com]

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"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

The washer and nut come with the strainer not the flat tailpiece

Because MOST of the time the slip nut is used for a slip joint connection which DOES use that gasket.

OK, in my case the strainer basket is metal (brass I think), the tailpiece is tubular plastic. I assume I should use a metal nut because if I over tighten a plastic nut on metal threads it may crack the nut, and who knows if the vibration from using the disposer on the adjacent bowl can shake loose the nut over time.

The metal nut comes with a flat washer. I get that most slip joints you use a beveled rubber or plastic gasket, I have plenty of that myself. If it's a tailpiece with a flange top you use the "top hat" washer. But they included a flat rubber washer, when does one use a flat washer?

Almost never ... but ... it is the least expensive to make.

==============================================

"Measure Twice & Cut Once" - Retired U.A. Local 1 & 638

The good flat rubber washers have cloth inside them and they don't squeeze into the tailpiece on tightening.

Also some 17gu p traps require a flat rubber washer because the nut is more shallow and a beveled rubber washer is too thick

The Flat washer and the
top hat" washer,( I have never called it that), are used interchangeably, although I always used the one with the cloth reinforement