Discussion: So-called 2" Hub x Slip Joint DWV Trap Adapter

[Reach4]

There are 1-1/2 inch hub trap adapters, which go onto a 1-1/2 inch pipe and accept a 1-1/2 slip joint trap.
There are 1-1/2 x 1-1/4 hub trap adapters, which go onto a 1-1/2 inch pipe and accept a 1-1/4 slip joint trap.

I now suspect a 2" Hub x Slip Joint DWV Trap Adapter is really a 2 x 1-1/2 trap adapter, which go onto a 2 inch pipe and accept a 1-1/2 slip joint trap.

AFAIK, there is no 2x2 plastic trap adapter, and there is no 2-inch slip joint trap. Have I got that right? It seems like such things would be useful. Why do you think they are not available, or am I mistaken?

 

[James Henry]

There is no residential sink that requires a 2" trap. Some commercial sinks require a 2" trap but they are required to have an indirect waste so a trap adapter is not needed. Slip joints on stainless steel commercial sinks that are subject to abuse constantly develop leaks so they are always glue fitted with cleanouts installed if needed. This is not to say that you couldn't find an adapter somewhere.

 

[Sponsor]

 

[Reach4]

I think I remember posts by people with glued 2 inch traps under a kitchen sink. They want to change the layout for a new sink or disposal, and they have a tough time. If that was slip joint trap, they would have had an easy time.

I understand there are localities that don't allow slip joint traps. Sad IMO.

 

[Jeff H Young]

never heard of putting a 1-1/2 trap on a 2 inch trap arm being legal . might be but I thought its illegal and looks like slop work. will it ever be a problem ? I think not

 

[Reach4]

never heard of putting a 1-1/2 trap on a 2 inch trap arm being legal . might be but I thought its illegal and looks like slop work. will it ever be a problem ? I think not

I was proposing that a 2-inch slip p-trap and a true 2-inch trap adapter should be available.

Just as people who glue a 2-inch trap into place might do, they could feed that with a 1-1/2 inch tailpiece.

 

[wwhitney]

Main reason to use a 2" trap under a sink would be take advantage of the longer allowance for a trap arm compared to 1-1/2" (UPC 60" vs 42" ; IPC 96" vs 72"). They do come in union plastic, so that plus a trap adapter on the inlet for a 1-1/2" tail piece would let you disassemble the trap for cleaning.

Cheers, Wayne

 

[Jeff H Young]

I think trap needs to match trap arm.. tailpiece can be smaller than trap

 

[Tuttles Revenge]

There are 2" slip trap adapers.. or things like them. I've found them in our shop and had zero clue as to their purpose until I was doing a remodel in a condo. Metal clothes washer boxes have 2" knockouts in them. They attach to the box with a 2" electrical box nut and trim out with a 2" slip joint nut to cover any sharp edges of the threaded pipe.

 

[wwhitney]

Since you mentioned electrical lock nuts, that sounds more like an electrical bushing than a plumbing product:

https://www.amazon.com/Sigma-Electric-ProConnex-49326-Insulating/dp/B000GASG2I

And for a laundry standpipe, you don't want a seal where the washer hose goes in, it should be an air gap, right?

Cheers, Wayne

 

[Tuttles Revenge]

Since you mentioned electrical lock nuts, that sounds more like an electrical bushing than a plumbing product:

https://www.amazon.com/Sigma-Electric-ProConnex-49326-Insulating/dp/B000GASG2I

And for a laundry standpipe, you don't want a seal where the washer hose goes in, it should be an air gap, right?

Cheers, Wayne

The locknuts were just the same style electricians use, flat with nubs to grip with pliers. The "slip joint" nut was exactly like the style you would see on a chrome trap, just larger but without any slip joint washer. Its purpose I think of was to avoid abrasion of the hose and maybe to give a slightly better asthetic. No ability to seal the connection.