Hi all, I've never glued flexible hose, in this case Spa-flex, into a PVC fitting. Can this be done? I have some 1-1/2" spa-flex I'd like to attach to my overflow for some flexibility. Does it glue to fittings the same way that hard PVC pipe does? Just use purple primer & PVC glue? Thanks
Glueing spa-flex into PVC?
- Thread starter HowieB
- Start date
builderguy
New member
Just use a heavy amount of glue and scuff (sandpaper) the spaflex otherwise it doesn't always adhere well. I would use Red Hot Blue Glue too...it's stronger than some of the others.
lllosingit
New member
I spoke with our adhesive rep about this one time and he said twisting after putting the parts together weakens the joint so to make sure they are lined up before pressing them together. He said twisting causes air bubbles in the joint and more likely to fail.
lllosingit
New member
Are you talking about barbed fittings or regular PVC pipe fittings?
needmore-reef
New member
I think he is talking about nylon tubing on barb fittings.
D-Nak
Active member
I'd have to disagree with your adhesive rep. Everything I've read and seen suggests to twist when gluing to strengthen the bond. Simply pushing in the tubing, especially with PVC that's been freshly cut (with a hacksaw for example) may have burrs on the end, can create a groove or channel in the glue which creates a weak spot. Twisting the piece removes this channel as the glue spreads over it.
Also, I believe that twisting will help to eliminate bubbles, rather than introducing them, as PVC cement moving laterally will "smear out" the bubbles.
Either way, I bet both techniques can produce a leak-free joint. As with many things in the hobby, without scientific testing and metrics to back up a claim, it's all hearsay. :rolleye1:
needmore-reef
New member
I make a 1/4 turn twist. Said to in a plumbing book, so far no issues. I also sand both fitting and pipe and coat both with clear glue.
lllosingit
New member
I tend to trust what he says considering his job depends on it. He knows more about adhesives than anyone I have ever met.
P.S You should clean/sand the burrs off before gluing.
Your right about both producing leak free joints but in my line of work they have to pass inspection and a pressure test so I have to make sure it's done right the first time.
uhuru
New member
I have a bottle of 795 PVC Cement right here, specially designed for flex PVC (can also be used for rigid with or without flex PVC). It says on the instructions to twist. I would trust the manufacturer's instructions.
IMO 1 1/2" flex PVC is not really that flexible unless you heat it up first. In fact the "memory" it has from being coiled up for a long time can make it even harder to work with than just rigid pipe and elbows.
Nathan.Titulaer
New member
I also agree with the spa flex hose I used it and barb fittings on the return on my 60 and the memory of it was horrible. It was close to the end of the role and was incredibly difficult to work with so now I am turned off the idea of it.
builderguy
New member
I use spaflex where I just need a little forgiveness in the run, or when I want to provide some vibration dampening. If you need a lot of flexibility I would go with the reinforced nylon tubing or the kink-free tubing.
BigOldReef
New member
You definitely want to use the 795 glue for spa flex. The regular PVC glue will seal it, but after several years it gets brittle and the adherence fails.
Jaycen B.
New member
Yes, this is a very old thread, but I have to correct and explain several things here.
#1. You do not twist flexible pvc pipe when gluing it into fittings. It has nothing to do with bubbles. The reason why is that when you cut flexible pvc pipe you will note it never cuts perfectly straight. There is always a little bump on the end. If you were to twist the flexible pipe what happens is that the little bump acts as a swipe and REMOVES glue (and pvc plastic) creating a spot behind it with the glue (and pvc plastic) are being swiped away. And it does so at the most critical point in the glue joint: the base of the socket.
For the real reason why, keep reading.
PVC pipe and fittings are what is called an interference fit. The socket is tapered so that at the base (bottom) of the socket the diameter is actually smaller than the pipe that is being inserted into it. That is why when you dry fit pvc pipe to the fitting it only goes in about 1/2 way w/o a lot of force. When you glue the pipe into the fitting the solvent in the primer "melts" the pvc plastic in the pipe AND the fitting so that you make a good joint because "no two solid objects can occupy the same space." The solvent is making the pipe and fitting NON SOLID at the moment you make the joint. So by twisting the pipe that little bump on the end of the flexible pvc pipe swipes and REMOVES pvc plastic to another point in the joint creating a "divot" in the wall of the socket behind the bump. That divot will be a weak spot in the glue joint and could cause a leak.
You are never to twist flexible pvc pipe when making a glue joint. The reason rigid pvc pipe is twisted is to assure an even spread of the glue. Which is why I made our video https://www.youtube.com/embed/QITVd4N7064 to show the correct way to make a pvc glue joint. With rigid pvc pipe you can be a little lazy with your glue application and twist will help recover your mistake. HOWEVER if you cut rigid pvc pipe crooked or at an angle you do not twist because it'll do the same thing (remove material). So if your pipe cuts are not perfect or you are using broken pipe, do not twist it.
Yes, lots of people can do these things incorrectly and not have a leak. That is because the system is engineered to take many of these things into consideration. The bottom 1/3" of the socket is where the joint is really sealed and as long as you have a continuous joint all the way around it, you should be okay.
#2. Barb or insert fittings. You never use barb or insert fittings with flexible pvc pipe. The spiral will actually start to unwind itself and over time due to the difference in ID of the pipe between that which is over the fitting and that which is not and the joint could fail. (Yes, if you have a clamp on it that will keep it from further unwiding.) However the pressure in the pipe is acting to expand the pipe and pull it away from the barb, thus compromising the seal. Also it's very hard to get the insert fittings into the pipe. If you want to use barb/insert fittings use vinyl tubing, the fiberglass reinforced or hybrid hose. Those products are engineered for use with barb fittings.
#3. "Flexible pvc pipe glue" .... there is no difference. It's a marketing ploy to get you to buy another can of glue. We recommend the clear or blue glue, medium or heavy bodied. We do not recommend the gray because it drys too hard (and becomes brittle over time.)
My qualifications:
Gluing flexible PVC pipe since 1972. I've made well over a million glue joints. I've been in the swimming pool, hot tub, plumbing, aquarium and irrigation almost the entire 45+ years of my career. I've fixed thousands of leaks in pvc joints. To see one of my greatest secrets on how to do so, see this video https://www.youtube.com/embed/wo-R0oqnMpc I made a couple years ago.
Chief Technical Support for FlexPVC.com since 2002.
#1. You do not twist flexible pvc pipe when gluing it into fittings. It has nothing to do with bubbles. The reason why is that when you cut flexible pvc pipe you will note it never cuts perfectly straight. There is always a little bump on the end. If you were to twist the flexible pipe what happens is that the little bump acts as a swipe and REMOVES glue (and pvc plastic) creating a spot behind it with the glue (and pvc plastic) are being swiped away. And it does so at the most critical point in the glue joint: the base of the socket.
For the real reason why, keep reading.
PVC pipe and fittings are what is called an interference fit. The socket is tapered so that at the base (bottom) of the socket the diameter is actually smaller than the pipe that is being inserted into it. That is why when you dry fit pvc pipe to the fitting it only goes in about 1/2 way w/o a lot of force. When you glue the pipe into the fitting the solvent in the primer "melts" the pvc plastic in the pipe AND the fitting so that you make a good joint because "no two solid objects can occupy the same space." The solvent is making the pipe and fitting NON SOLID at the moment you make the joint. So by twisting the pipe that little bump on the end of the flexible pvc pipe swipes and REMOVES pvc plastic to another point in the joint creating a "divot" in the wall of the socket behind the bump. That divot will be a weak spot in the glue joint and could cause a leak.
You are never to twist flexible pvc pipe when making a glue joint. The reason rigid pvc pipe is twisted is to assure an even spread of the glue. Which is why I made our video https://www.youtube.com/embed/QITVd4N7064 to show the correct way to make a pvc glue joint. With rigid pvc pipe you can be a little lazy with your glue application and twist will help recover your mistake. HOWEVER if you cut rigid pvc pipe crooked or at an angle you do not twist because it'll do the same thing (remove material). So if your pipe cuts are not perfect or you are using broken pipe, do not twist it.
Yes, lots of people can do these things incorrectly and not have a leak. That is because the system is engineered to take many of these things into consideration. The bottom 1/3" of the socket is where the joint is really sealed and as long as you have a continuous joint all the way around it, you should be okay.
#2. Barb or insert fittings. You never use barb or insert fittings with flexible pvc pipe. The spiral will actually start to unwind itself and over time due to the difference in ID of the pipe between that which is over the fitting and that which is not and the joint could fail. (Yes, if you have a clamp on it that will keep it from further unwiding.) However the pressure in the pipe is acting to expand the pipe and pull it away from the barb, thus compromising the seal. Also it's very hard to get the insert fittings into the pipe. If you want to use barb/insert fittings use vinyl tubing, the fiberglass reinforced or hybrid hose. Those products are engineered for use with barb fittings.
#3. "Flexible pvc pipe glue" .... there is no difference. It's a marketing ploy to get you to buy another can of glue. We recommend the clear or blue glue, medium or heavy bodied. We do not recommend the gray because it drys too hard (and becomes brittle over time.)
My qualifications:
Gluing flexible PVC pipe since 1972. I've made well over a million glue joints. I've been in the swimming pool, hot tub, plumbing, aquarium and irrigation almost the entire 45+ years of my career. I've fixed thousands of leaks in pvc joints. To see one of my greatest secrets on how to do so, see this video https://www.youtube.com/embed/wo-R0oqnMpc I made a couple years ago.
Chief Technical Support for FlexPVC.com since 2002.
acer
New member
Thank - you for posting this - I purchased both rigid and flexible PVC from "FLEXPVC" and forgot to get glue. SO the 2 part = primer(purple) from Home Depot will work on both- correct?
http://www.homedepot.com/p/8-oz-PVC-Handy-Pack-Purple-Primer-and-Solvent-Cement-302483/100151579
What type of pipe dope should I use on the threaded joints? Everybody seems to use Teflon tape- but have heard/seen that is a no-no ?
http://www.homedepot.com/p/8-oz-PVC-Handy-Pack-Purple-Primer-and-Solvent-Cement-302483/100151579
What type of pipe dope should I use on the threaded joints? Everybody seems to use Teflon tape- but have heard/seen that is a no-no ?
Last edited:
This is what I used on my reef system:
https://flexpvc.com/cart/agora.cgi?p=Thread-sealantsTeflonAndPaste&p_id=Weld87685&xm=on&ppinc=detail
If you read the MDSS you will see it's totally benign and non-toxic.
You can also watch this video on why you want to use thread sealant instead of "teflon tape."
https://www.youtube.com/embed/prsgzY7aypE
HTH.
