Can I attach brass valve to plastic pipe?

Hello - I'm about ready to tap into my under-sink Kitchen cold water supply, to install an icemaker.
The supply coming out of the wall is a 1/2" plastic pipe. Here's a pic of it:
http://tinyurl.com/2qzkqk
It appears that the current, plastic stop valve is screwed into the plastic pipe. The new stop valve I have is brass. My question... can I just screw my new brass valve into the plastic supply pipe - where the plastic valve is now attached?
If not, what fittings do I need to make the plastic supply pipe coming out of the wall compatible with my new brass stop valve?
Thanks for any suggestions,
Don

donk said:

The new stop valve I have is brass. My question... can I just screw my new brass valve into the plastic supply pipe - where the plastic valve is now attached?

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No. What you have there is some kind of compression fitting system, not regular pipe thread.

donk said:

If not, what fittings do I need to make the plastic supply pipe coming out of the wall compatible with my new brass stop valve?

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One possibility is to simply place a compression tee (brass or plastic) in the 3/8" supply line going up to your sink, but others here might have a better suggestion or two.

For sure the way to go. 3/8" compression tee into the riser to the sink.

Hi - thanks for the responses so far.

>>For sure the way to go. 3/8" compression tee into the riser to the sink.

Yeah, I already have a flexible plastic 3/8" compression tube to go from the stop valve to the sink. But, my problem is this:

I need to remove the plastic stop valve that is there - and replace it with a dual outlet brass stop valve (to install an icemaker).
So, how in the heck can I get a brass valve to connect to the plastic supply pipe coming out of the wall? The pipe "seems" to have female threads, since it looks like the current plastic valve is screwed into it.
Thanks again,
Don
PS: here's another link to the pic of the current valve and pipe:

It looks to me like you can remove the riser, unscrew the existing stop, screw in the new brass one using either teflon tape and/or pipe dope, and then reconnect. Now, the rigid riser may no longer line up or fit, so you might want to replace it with a flexible stainless steel supply line.

I prefer the hookup to the icemaker to be soft copper tubing, but that's me. In either case, you need to leave a fairly big loop behind the frig so you can move it in/out to service without crimping or stressing the tubing.

You have enough of a stub sticking out of the wall to use a compression shutoff. I think those require an internal ferrule to be inserted prior to attaching the compression valve to strengthen the walls so they don't collapse when you tighten up the compression fitting. This would be better in my estimation, since the screw fitting could (not saying it would) split as it ages, especially if you tighten it up too much.

donk said:

I already have a flexible plastic 3/8" compression tube to go from the stop valve to the sink. But, my problem is this:

I need to remove the plastic stop valve that is there - and replace it with a dual outlet brass stop valve (to install an icemaker).

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You do not need to replace the stop valve you already have. All you need to do is to close your existing stop, then cut about an inch out of your current supply line to the sink and install a compression tee. At that point, you can run the line to the icemaker from that tee, then turn your existing stop valve back on. And if the line to your icemaker needs to be 1/4", I believe you can buy a 3/8 x 1/4 x 3/8 compression tee. Also, you should place inserts inside your plastic lines before compressing them with brass, and plastic ferruls would be best. The picture below is of a tee I am already using to do exactly what you need to do. It is brass with regular ferruls, and I have the inserts in the tubing.

donk said:

So, how in the heck can I get a brass valve to connect to the plastic supply pipe coming out of the wall? The pipe "seems" to have female threads, since it looks like the current plastic valve is screwed into it.

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What you actually have there is a compression nut around the pipe and screwed onto your compression-connection stop valve. That is why Jadnashua mentioned a "compression shutoff", as you would need the same if you were to replace that one. And there is no need to do so unless your dual-outlet valve has the same size compression inlet.

PS: Please pardon the corroded nut on that tee in the picture! It was late that night and that was what I had found available in my garage stash. That tee does not leak!

Thanks for the reply.
I think I will try to just screw my brass shutoff valve into the plastic supply pipe coming from the wall - and hope that it works. (I'll use teflon tape like you suggested).
But --
If it leaks, you suggested I have enough of a stub to put a compression fitting on. That'll be plan B. My only question now is... how would I get the current plastic fitting on the end of the stub to come off? It looks like it might be cemented on there. I circled it in the picture. Any idea on how it might come off so I can put a compression fitting on the stub?

If it is glued on (and it doesn't look like it has aplace for a wrench to hold it so I'm thinking glued), you'll have to cut it off. If it is actually a nut and is part of a compression fitting, it will probably just slide off once the thing is loosened.

If it is not a nut, and is a threaded adapter glued onto the end of the pipe, then you'll have to cut it off. A hack saw or a tool designed to cut that stuff would be needed.

You'd want to hold that piece that the valve screws into with some pliers so you don't end up twisting it off in the wall while you unscrew the valve.

donk said:

I think I will try to just screw my brass shutoff valve into the plastic supply pipe coming from the wall - and hope that it works.

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That is not going to work. Your pipe has no threads. That nut (with the threads) on your pipe turns loose on that pipe, and anything you screw into that nut -- that nut is what actually turns there -- must be a matching compression fitting your nut can seal the pipe against.

donk said:

... you suggested I have enough of a stub to put a compression fitting on ... how would I get the current plastic fitting on the end of the stub to come off? It looks like it might be cemented on there.

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It is not cemented. It was slipped onto the pipe, then a compression ferrul was also slipped onto the pipe (and is now inside the nut), and then the nut was tightened (to compression seal the pipe) onto your stop valve.

donk said:

Any idea on how it might come off so I can put a compression fitting on the stub?

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You already have a compression fitting on the stub, and the only way to remove it is to cut the pipe. And if you decide to do that, first screw the nut back off of your stop valve, then push the nut back to the wall, then cut the pipe just behind the ferrul that is presently inside the nut ... and then be prepared to open your wall and replace the pipe if it is next found to be too short to accept another nut and ferrul!

I'm assuming that you do know what you've got and can tell pretty well just by looking at it. Those supply valves with male npt threads are a bit unusual. There are several ways to do this. Personally, I prefer to be able to shut off the water supplies separately. If it were me I'd put a tee on the stub out then separate valves for the icemaker and sink supply. It wouldn't matter whether they are compression or threaded types as long as you use the proper threaded adapter (not necessary if compression fittngs are used).

Randyj said:

Those supply valves with male npt threads are a bit unusual.

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Do you think I might be wrong about what we can see there? I do not recall ever seeing a hex-sided female adapter. But, maybe there is such a thing even though I have never seen gray pipe cemented. And, I suppose it could be possible there is such a combination as a nut and ring that will seal against the end of an mpt nipple or fitting ...

Thats a Qest valve,used for polybutylene pipe,and they are getting harder to find nowadays.It wont work with a brass valve because it requires a lockwasher-type ring in the threaded nut.
Heres a link to a page which shows the fittings available.Dont see any dual stop valves,so you will have to work out something,most likely with a tee and an additional stop valve.
Or you could cut the whole thing off and transition to pex.Or do the above stated thing with the tee in the faucet riser.All these are makeshift kind of methods,but thats the way it is when dealing with the PB plumbing.

Well I see the link gets hosed,so please do a search for "Qest fittings".

Lancaster said:

Thats a Qest valve ...

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Ah, yes! I knew that looked like my water-softener connections, but I could not remember what it is called!

After work today, I will try to post a picture of what is inside ...

That is Qest with PB pipe. If the brass T shown a few posts back has the brass compression sleeves in it you need to change it over to a qest compression T or you may find your self with flooded house. I would change it over to qest reguardless.

How long have you been living in this home? Are you aware of the problems associated with this pipe?

Cass said:

If the brass T shown a few posts back has the brass compression sleeves in it you need to change it over to a qest compression T or you may find your self with flooded house. I would change it over to qest reguardless.

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Yes, I understand. That particular line is only a temporary one servicing a toilet and bathroom sink in our bedroom during some remodeling, and I will eventually be replacing it altogether.

Donk, here is a picture of what you have coming out of your wall. The pipe has no threads of its own. Rather, the nut was slipped over the pipe stub and a Qest (no "u" in Qest, I just discovered!) compression ring was added, then the pipe was attached to your valve by tightening the nut to it. You could get all of that off of there by pushing the nut back and cutting either the pipe or the compression ring, but then you would have to use another one just like it. As I recall, I paid about $4.00 just for one nut and ring when I was re-plumbing our water softener.

Overall, your best bet is to simply put a tee in the supply line going up to your sink, and if you want to be able to stop the water to the icemaker separately, to then add a stop valve somewhere between that tee and your icemaker as Randy has suggested. And as others have said or have at least implied, you should not use brass compression sleeves like you can see just barely sticking out of the nuts in my picture. Those should be plastic, and I would still add the brass inserts inside the tubing to prevent it from being crushed during compression.

valve

Without going through the voluminous replies that have already been submitted, I don't know if anyone addressed what you have there. It is a Qest compression valve. When you unscrew the valve you will find a cone "plastic" washer that slides off, often with some difficulty, and a toothed metal washer the grabs the plastic. Sometimes that can be removed by carefully wiggling it, but be careful because it is very sharp. Otherwise clip it with some tin snips and take it and the nut off. Then you can use a plastic ring and brass insert, (available at Home Depot) to install your valve. Your bigger problem, however may be the polybutylene tubing in the walls.

Wow, thanks to everyone for all the replies.
What I've learned is that I'm way too freaked to mess with removing that stop valve held on by the Qest fitting. The stub coming out of the wall is pretty short as it is, and I don't wanna mess with it.

So, I think I'll try what LeeJosepho suggested - attach a brass Tee to the pipe going up between the stop valve and the sink.
Now I've got 2 questions about "that"...

1. Will I be able to cut the pipe while it's still connected (water shut of at stop valve of course)? And will one of those little circular tube-cutters sold at Home Depot work?

2. Just let me make sure I have all this right about making the compression connections to the Tee...
I put "brass" inserts inside the tube.
I use "plastic" sleeves.
I use teflon tape on the brass threads of the compression nut.
Is all that right?
Thanks again - Don
PS: here's the pic again of the stop valve and pipe running up to sink:

stop valve

I have absolutely no use for the valve nor the PB line to the faucet. Personally, I would change both of them, and the other side also while I was at it.

donk said:

1. Will I be able to cut the pipe while it's still connected (water shut of at stop valve of course)? And will one of those little circular tube-cutters sold at Home Depot work?

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Whether or not you first remove that supply line is optional if you can get to it easily and have enough room to do the work comfortably. And while I would use a knife (at risk of cutting into my thumb!), I can imagine a tubing cutter should work just fine.

donk said:

2. Just let me make sure I have all this right about making the compression connections to the Tee...
I put "brass" inserts inside the tube.
I use "plastic" sleeves.
I use teflon tape on the brass threads of the compression nut.
Is all that right?

Click to expand...

The teflon tape is unnecessary there, but not harmful.

I wouldn't use teflon tape on your compression fitting. You definately want to use plastic ferrules.

There also pex quick compression fitting that can be used, (3/8x3/8x1/4) very simple cut your pipe slip your 3/8" line in the top and bottem, and 1/4" in the side. Attach to your fridge and your done. If you use the pex fitting don't use copper tubing. Have had several customers tell me that they tried pex with copper and couldn't get them to seal.