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paulz
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# Posted: 23 Feb 2022 09:53am
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Is using brass compression fittings on CPVC a no-no? That's what I've got, and they have been fine except for this week after running super hot water through the system. I was able to tighten the leaking (metal) valve and stop the leak, just wondering if I'm headed for future trouble.
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travellerw
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# Posted: 23 Feb 2022 10:58am
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What kind of compression fittings?
Do you mean compression fittings with an olive? Like the one below?
Or do you mean the compression fittings where you use special pliers to squish the ring around the pipe?
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paulz
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# Posted: 23 Feb 2022 11:00am
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An olive? New term to me. Yes, like the pic, only it's a valve not a coupling. Slide the nut on, slide the brass ring on, slide the valve on, tighten the nut.
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travellerw
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# Posted: 23 Feb 2022 11:16am
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I think its a more common term in Europe. If you look at the brass ring you will see why its called that.
Anyway.. I think you are asking for trouble if you are using fittings with a brass ring. I have seen them work without issues, but technically there are different compression fittings for plastic pipes (pretty sure they have a plastic olive). I wouldn't trust one in a critical spot where a leak could go unnoticed.
I'm partial to the press on fittings (Shark Bites) or a traditional crimped fitting for pvc/cpvc. If you are only doing a few, then the Shark Bites are the way to go (they make valves with these fittings). If you have a bunch, then it can make sense to buy a crimping too. There are 2 types of crimping tools. One that crimps a copper ring and one that uses stainless rings where part is squished. I have used both many times and they both work great. I prefer the stainless one in areas that may be higher humidity or even outside.
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Steve_S
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# Posted: 23 Feb 2022 11:28am
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There are differences between PEX & PVC fittings and couplers and you have to use the correct types lest ye suffer issues. I used PVC way back when and learned not to do that again. When I built my place, it's all PEX with Crimped fittings. I dunno if in 2022 Sharkbite makes them for both or not anymore... as PVC has really fallen out of favour due to various issues over the years. Really old PVC from the 70's into the 80's also had issues with leaching chemicals from the plastic into the water and for deterioration when exposed to UV Light... Much of that was addressed but a tad too late.
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paulz
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# Posted: 23 Feb 2022 11:43am - Edited by: paulz
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I think I have seen the plastic olives, maybe that's the ticket, if I can get the brass one off now.
The valve is outside the wall, like a sink valve, only it goes to my shower. I didn't have a shower stall yet when I plumbed, so I just put the two valves in down next to the toilet valve. I later ran braided hoses up to the shower valve, again external. It's a bit funky but it works.
Anyway if I can't get the brass olive off I can probably cut the pipe and glue a coupling on then do something else. For now I guess I'll just try the 'tighten the shit out of it' method and hope for the best. I really think the super hot water is a factor, I have the same arrangement on the toilet and sink valves and so far no leaks. I searched on 'brass compression on pvc' and didn't see any 'don'ts'. The CPVC is thinner than regular PVC, probably more likely to leak with compression fittings.
Thanks traveller.
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travellerw
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# Posted: 23 Feb 2022 01:28pm - Edited by: travellerw
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Quoting: paulz For now I guess I'll just try the 'tighten the shit out of it' method and hope for the best.
Its definitely the hot water that is the problem as PVC and CPVC both suffer from expansion and contraction with temp changes. The brass will have a completely different rate. The differences will cause the seal to fail.
Sorry.. my brain wasn't working right above. I substituted PEX for PVC/CPVC. As far as I know, there are no "crimp" connection for PVC/CPVC. Its either glue based or "push-to-connect" fittings (like Sharkbite). I'm not sure if Sharkbite makes connectors for PVC, but one brand I have seen is "Pro-Connect"
Why not just cut the valve off and put on a glued on valve? Easy and definitely won't leak EVER!
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paulz
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# Posted: 23 Feb 2022 01:49pm
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Glue on valve would be plastic then? I guess that would work, never used one. There must be a way they connect metal valves to PVC. Threaded on maybe? Or maybe CPVC is a different ballgame being heat compatible.
Should have done PEX..
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travellerw
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# Posted: 23 Feb 2022 02:29pm
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Yup.. A glue on plastic ball valve. I'm pretty sure they even have ones with a threaded end that fits the standard braided hoses (for connecting to toilets and faucets). Careful with the braided hoses as I think they are only rated to 160F.
Another option would be a glue on fitting threaded on one end. Then you could thread on the brass valve using PLENTY of teflon tape to ensure the seal.
I would trust either of them to last many years.
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ICC
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# Posted: 23 Feb 2022 05:50pm
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As mentiuoned above: cement an adapter onto the CPVC stub; CPVC to a brass pipe thread. Then the valve can be changed out easy if ever necessary.
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paulz
Member
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# Posted: 23 Feb 2022 08:00pm
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Quoting: ICC CPVC to a brass pipe thread.
What piece connects CPVC to brass pipe thread?
And I'm still wondering how those rings came to be called olives? Oh as in a slice of an olive? Think I'll have a martini and mull it over. 
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Fanman
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# Posted: 23 Feb 2022 08:10pm
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Compression fittings require the pipe to deform, and CPVC is too hard and brittle for that.
What ICC is talking about is a fitting with one side that cements to the CPVC pipe, the other side is threaded to screw it onto the next pipe fitting.
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travellerw
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# Posted: 23 Feb 2022 08:33pm
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Quoting: paulz And I'm still wondering how those rings came to be called olives? Oh as in a slice of an olive? Think I'll have a martini and mull it over.
If you look at pictures of big ones, they look a little like an actual olive. Since they are tapered on the ends and have a hole in the middle.
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ICC
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# Posted: 23 Feb 2022 08:46pm
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In the US and Canada that brass inner part is known as a compression sleeve.
Adapter, cpvc to threads, available in both F and M metal threaded end with the other end solvent welded to the cpvc pipe. Google.
https://www.lowes.com/pd/Apollo-1-2-in-CPVC-CTS-Slip-x-Stainless-Steel-FPT-Adapter/10 02751846?cm_mmc=shp-_-c-_-prd-_-plb-_-ggl-_-LIA_PLB_142_Pipe-Fittings-_-1002751846-_- local-_-0-_-0&ds_rl=1286981&gclid=Cj0KCQiA09eQBhCxARIsAAYRiylHMCQtaZXtNE2h4VG1v8R-ain LqvO07Qqe5022Y_gCPCD8SWLSGxgaAiBzEALw_wcB&gclsrc=aw.ds
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paulz
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# Posted: 23 Feb 2022 09:55pm
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paulz
Member
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# Posted: 31 Mar 2022 12:57pm
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OK, got that sorted..
Now, is there a fitting that clamps this SS covered nylon tubing onto 3/8" metal tubing, which it slides fairly tightly over?
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paulz
Member
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# Posted: 31 Mar 2022 02:13pm
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Think I found it.
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Fanman
Member
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# Posted: 31 Mar 2022 06:00pm
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That would work, as long as it's the appropriate size for the tubing on both sides. You say the metal tube is 3/8", if the nylon tube slides over it's probably 7/16 or 1/2". You might need to buy two different size compression to NPT (pipe thread) adapters, and join them with a NPT coupling.
On the nylon tube side the compression fitting should have an internal metal sleeve and plastic compression sleeve, as shown in the picture you posted. On the metal tube side, no internal sleeve and brass compression sleeve.
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