Before I thought seriously about plumbing I thought traps trapped things: the wedding ring dropped down the drain, stuff that clogged the pipe (for easy removal). I bought a trap for my clothes washer, but only one side of the bend is threaded, rather than both, as in all the slip-joint traps I have installed. What good is it? I can't remove it. I know the purpose of a union when plumbing threaded fittings. I don't see the purpose on a trap that has to be welded on all the other joints. I've thought of attaching a short stub to the inlet, attaching that to the pipe with a Fernco sleeve, to make it removeable.

You can glue in a slip trap adapter on the inlet to make it a slip joint

The trap we are discussing is sch. 40 not tubular which has a much thinner wall

I’m not sure why they are used, an 1 1/2” pvc trap is not hard to cable through and they are cheap enough and not worth re using

It's a clothes washer: it's plumbed with 2" drain pipe. I found a trap adapter for 2", but the nut is too small to attach to 2" PVC. I've never seen 2" slip-joint.

2” throw it in the trash… no use for it buy a trap that is solvent welded on both inlet and outlet

The swivel is to allow for slight 'misses' left-right with the roughing.

The swivel is NOT for trap disassembly after installation.

Sometimes referred to as a L.A. Trap where they were first permitted.



They were NOT permitted previous to 1970? in the NYC code.

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

The union does come in useful sometimes. Say there is a a tailpiece to be replaced under a kitchen sink, the tailpiece is longer than it needs to be and there is not enough give in the drain piping. Undoing the union enables easy removal of the tailpiece.

All solvent welded joints will swivel for period of time and the pipe is quite flexible so missing a little bit on the rough in would usually work with any style trap

If it isn’t meant to be taken apart it shouldn’t have a nut to begin with

we are NOT referring to any 'swivel' in the joint before the solvent 'sets'

we are referring to a mechanical joint in the trap itself

said joint will allow the trap inlet to swivel sideways in refernce to the 'centerline' to allow for 'slight' errors in the rouging

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

MA code requires a full size cleanout under kitchen sinks.
it allows us to install a union type trap so the trap is removable. this passes the code as a full size cleanout.