Sealant Compatible with PEX Pipe
PJL1941
| Posted in GBA Pro Help on
I have accidentally drilled a tiny hole in a Pex water pipe. The pipe is embedded in a brick wall. I wish to plug the plex pipe with underwater sealant by pushing the sealant into the drill hole and onto the hole in the pipe. I need to know what sealant to use which is compatible with Pex Pipe
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PJL1941,
Unfortunately there are no sealants that can repair pressurized pex waterlines. You need to expose the hole and place a coupling there, or alternately replace the length of pex.
How did the pipe get into the wall? Was the wall built around it, or was it fished in after the wall was built? Because if it was fished what you really want to do is fish a new one. If it was built in I think the only way to fix it in place is to make the hole in the brick large enough to get a crimper in there and put in a crimp fitting.
If the pipe moves, fishing isn't hard, you just attach the new pipe to one end of the old pipe and pull the other end.
I think the only way to actually seal polyethylene is to weld it with melted polyethylene. If it's really dire you might try that as a last resort. The worst thing that could happen is you ruin the pipe.
PEX is cross linked polyethylene, which isn't quite the same as "regular" polyethylene. Regular polyethylene can be thermally welded, but I have conflicting info as to if PEX can be thermally welded or not -- some info (from reliable sources too), says "NO", other's say "YES", but specify fancier than usual equipment to do it. Regardless of if it's possible or not, thermal welding equipment for plastic isn't something the typicaly DIYer -- or even contractor -- is likely to have available to them.
You're pretty much stuck with the need to make a mechanical repair, basically crimp in a coupler fitting. DC's idea to re-fish the pipe would work too. If you go that route, I would drill a small hole an inch or so from the end of the old pipe and the new pipe, then wire them together with some thin steel wire. Go over that with a layer of tape (electrical tape works well, stretch it a bit while applying to keep a tight layer of tape), both to make the "splice" smooth, but also to keep the ends closely aligned. You don't want the end of the new pipe to jam on a stud on the way through the holes. The wire will make things strong enough that it isn't likely to come apart as you pull the new line through. It is exceedingly frustrating to have old and new pipe or cable seperate when fishing this way (ask me how I know :-D). Best to go a little overboard splicing things together so that you can be sure not to have problems.
Note that many PEX fittings aren't reuseable, so if you fish a new run of pipe, plan on cutting out and replacing whatever fittings will be on either end when you're done.
Bill
You're thinking like an electrician! PEX crimp fittings go on the inside, just crimp the two sections together and tape them with electrical tape and the assembly can be fished.
Crimp PEX fittings are reusable, there's a special tool to remove the crimp rings or in a pinch you can grind them off with a Dremel or an angle grinder.
Cross-linked polyethylene, which is what PEX is made from, does not weld in a strict sense because it doesn't melt, it turns brown and gets brittle when heated. However, regular polyethylene does melt, and it adheres to PEX when liquified.
This kit is recommended by the manufacturer specifically for repairing PEX:
https://www.polyvance.com/Airless-Welders-1/KCWPRO/
See also:
https://www.polyvance.com/video/miscellaneous-repairs/how-to-repair-cross-linked-polyethylene
It's only $89.
Still sounds like a weak spot though, my preference would be to rerun that section of PEX if possible, otherwise use a coupler. You'd probably need a least as much clearance to get in there with the welding setup, so the coupler is probably cheaper.
I don't trust the fittings to be reused after removing the ring. Too likely they won't seal afterwards (which I've seen with barbs before), or that the fitting will get damaged. I don't like risking that inside walls.
I didn't know about the welding setup to use on PEX. One of the references I have saying you can't weld PEX is from US Plastics, which also sells the welding setups, so that's really surprising to see!
BTW, after working with electrical stuff as long as I am, *everything* looks like wiring :-D
Bill