Flex PVC + ABS Fittings = No!

[combatwombat]

Just a PSA for anyone searching.

After having a hard time finding pvc sweep fittings locally, I thought I'd test gluing up a length of 2" flex pvc to an ABS fitting using transition glue like you would with hard pipe PVC to ABS. Primed, glued, and left to cure for about 12 hours. It didn't come right off, but I was able to pull the fitting and pipe apart with some force and the glue joint broke without much force at all.

Maybe okay inside the pond in a pinch, but don't recommend this combo if you can avoid it. Will test again with PVC sweep fittings from the local plumbing supply house + a heavy bodied glue to see how that performs. Assume it will work a lot better. True pressure fittings with the deep sockets are clearly best, but have never seen one designed with sweeps.

 

[GBBUDD]

Regular pvc sweep 90's or STREET 90's is probably what you need to look for . also depending on the flex pvc you got there are now many different types of glue there HD there low heat and standard and abs . i believe the blue low heat is the one recommended but i have always used the HD

 

[combatwombat]

I can't find anything with a sweep in pressure pvc. Lots of options for DWV—pvc or abs—but they all have the shallow sockets that flex pipe doesn't play nice with. The pressure fittings have the nice, deep sockets, but they're all hard 90s. Maybe if I go to Ferguson across the river I can find one for $50 a fitting. lol

 

[GBBUDD]

You won't be pushing enough psi to need Pressure pvc fittings yes it's nice to get the extra depth in the socket but other then that it's not needed.

 

[combatwombat]

I'm more concerned about bends near fittings. If you don't handle it with kid gloves at all times, you would probably pop your joint. And if it's behind a rock, you might not realize it until it's a real pain to fix. That said, I'm considering not gluing my joints in the pond at all since psi is so low and a small leak inside the liner is not meaningful.

 

[GBBUDD]

I'm more concerned about bends near fittings. If you don't handle it with kid gloves at all times, you would probably pop your joint. And if it's behind a rock, you might not realize it until it's a real pain to fix. That said, I'm considering not gluing my joints in the pond at all since psi is so low and a small leak inside the liner is not meaningful.

go with fernco's if you want to do that . There was a guy who built his the same time i was and he refused to clean the joints with primer it didn't work out that great. and there's one way that works i do have one joint with no glue but it's in the bog locked up by gravel and rock that i use to pump the water out of the pond at 12000 gph They do have sweep elbows in fernco's

 

[combatwombat]

What went wrong with the unglued fittings?

 

[GBBUDD]

Nothing i take it apart to drain the pond but it has to be dug out a little then i just bend the flex line toward the back yard and dump 6000 gallons in 30 minutes.

 

[combatwombat]

I meant the other guy who you said it didn’t go well. I thought you were warning me away from leaving fittings unglued inside the liner.

 

[GBBUDD]

your going to hide the pipe behind rocks. Try moving around a 300 pound rock while swimming. He also did not keep the pipes in the liner and they blew out

 

[poconojoe]

Couldn't you use this?.....

 

[combatwombat]

@poconojoe: That’s exactly what I used.

 

[poconojoe]

I'm assuming you used primer, so what the heck happened?
Could it be the wrong primer?
Was there a special primer that came with that glue?
That glue states PVC to ABS. What gives?
Are you sure it is ABS you are using? Maybe it's polypropylene or CPVC? There are a few other plastic type pipes and fittings out there.

 

[combatwombat]

It’s ABS. The guy who runs flexpvc.com says he does not recommend transition glue for any scenario and says to not glue flex pvc to abs at all. This is probably why.

Primer on ABS is controversial. Some people say they use it with no problem, others say never use it because ABS is cellular core and primer can eat into the core.

 

[poconojoe]

It’s ABS. The guy who runs flexpvc.com says he does not recommend transition glue for any scenario and says to not glue flex pvc to abs at all. This is probably why.

Primer on ABS is controversial. Some people say they use it with no problem, others say never use it because ABS is cellular core and primer can eat into the core.

I'm thinking the only trustworthy way to join them is with threaded male/female fittings.
Do they make threaded fittings for ABS?
If so, are the threads the same as for PVC?
Add a few wraps of teflon tape to the threads and you should be good.
Add a threaded union if you want it serviceable.