Ok, joining PVC pipe is not rocket science I know, but today something happened I don’t understand. I failed my air pressure test on a sewer line I”m installing for an HO, basically I had 3 joints leaking air, one of them was a bad leak.
It’s cold outside, around 36 degrees. We’re using IPS Weld-On cement and primer which is supposed to be good down to -17 degrees. We’ve been heating the fittings for a few seconds with a propane torch to warm the fittings then apply primer and then cement I twist the joints some for a second or two as I join the pieces.
So far I’ve put in about 12 sewer lines. Two of them leaked air. What causes a PVC joint to not cement fully? Can the air temp screw it up? We put a line in two days ago, just as cold outside and pressure tested OK. So I”m not sure, what makes a joint fail, how can you NOT get a good solid PVC joint? I want to make sure I’m not doing anything wrong. Or could do better, a tip or two.
Replies
Clean and dry with cloth, no burrs, we clean with MEK then prime with purple to meet "inspection" requirements, in cold conditions coat male and female with "glue" (Polar Weld when it's cold) then seat 100%, immediately twist about 1/8 to 1/4 turn, hold in place for 30-60 seconds. Will never fail.
As POOLMAN says be sure to hold the joint for 30 to 60 seconds - the glue, while still liquid, can force the joint to open if you don't hold it.
The key I found is to always glue both pieces. Helps with the fit but seems to eliminate leaks.
Had a leaker 7 or 8 years ago. New house and had 3 leaks. Hooked up a vacume pump and pulled some vacume. Then hit each leaky joint with glue. Sucked it right in and took care of the problem. Probably wouldn't work on a remodel. DanT
"Clean and dry "Not nessecarily. The make glues for use WET.I have a pressure forced sewer main system. When the city installed this sytem they screwed up (or really the engineers/contactors) several ways.One was the the type of shutoff/checkvalves that they used randomly. They would clog up in the forward direction, but allow flow in the reverse direction.After blowing the hose off the pump twice in 2 weeks and then have sewage overflowing my tank they dug up and replace it with a shut off valve.They cut the line and glued the replacement on with sewage under pressure. Held it about a minute or so until it set.
BillHartmann: I've been reading your posts for quite some time, most are right on the money, but a glue that you can use wet I've never heard of [Been in trade since we used bamboo], so if you can give more info. I'm not too old to learn, thanks.......................................
"If all else fails, read the directions"
I was carefull enough to stay out of the hole while I they where doing it.But I did watch the operation, for several reasons. One the orginal contractor that the city had was worthless (actually they could be used as a bad example and the reason that they went bankrupt). The contractors that they had latter for an "upgrade" (fixing some of the first contractors mistakes) was somewhat better. But they could never figure out that fill dirt would settle.And after the inital installation I had installed a drain pipe which between my neighbors pump and mine and parallel to the discharge line and electric which was improperly installed. With a trench drain that was installed across the discharge line and they had to dig under it to get access.Anyway I was surprised that they could do it wet. IIRC I looked at the lable on the can and it did say wet.I googled on - PVC wet cement - and found a couple.http://www.pondandfountainpros.com/weld-on-2725.shtml
http://doitbest.com/DoItBest/Main.aspx?PageID=64&SKU=458511
http://doitbest.com/DoItBest/Main.aspx?PageID=64&SKU=434925
http://plumbing.hardwarestore.com/52-304-cements/pvc-wet-and-dry-cement-614649.aspx
http://www.herchem.com/products/pipecement.html (602xx)
http://www.tchristy.com/Redhot.asp.
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Hey every group has to have one. And I have been elected to be the one. I should make that my tagline.
Thanks for the info. I live and learn. "May the force be with you"
This is true, but they do not create the "BEST" solvent weld. We have used "hot" glue, or "wet" glue when we have had no choice, but we usually try to control our working environment to reduce moisture. Sometimes you just have to deal with it, and thankfully there are products to do just that!
Clean is still very important.
untill the circumstances change, my answer will remain the same...
Like someone else said, I prime and glue both pieces and twist. When its cold the glue will take a little longer to set. I usually go a little crazy with the glue and cleaner, I use a generous amount of each. I figure an extra bottle of glue and cleaner is a better problem than fittings that leak.
Part of the problem may be the heating with the torch. You may be creating a hot spot that causes the solvents in the primer and glue to volatilize prior to the glue bond being created.
I've glued miles of large diameter PVC. Clean and prime both male and female, lots of glue on both and as other mentioned get them fully together, twist and hold for at least 30 seconds even better for a minute in the cold. Also hold in the final resting position of the pipe. I've seen guys hold up a joint and them crunch it down during the drying-breaking the bond of the uncured glue.
The other thing you may want to check is how the help is carrying the pipe. We did a water treatment facility where the laborers dragged the 20 foot stick creating a nice bevel on the male end. Suprise every joint failed.
Bruce
Have you used a torch to heat any of your fittings, or what doyou do when it's cold outside like in the 20's and 30's? See our problem is we have to cut over from a septic to a sewer grinder pump all in one day. That means we have to pressure test for the inspector to approve the cutover before we can start to backfill. AS such, we don't have 12 hrs wait time for the cement to fully cure. That is, until you excavate for 1 or 2 hrs, lay the pipe and join it you're already into the afternoon whereby the inspector can come by and check the air test. If we wait 12 hrs as recommended then that would be a day the HO would not be able to use the bathroom and such which isn't really a good thing. Ideally you want to get them back in business by the end of the day at most. The manufacturer of the cement suggested a warming blanket or torch to assist but it really gave no directions as to how to apply the heat, for how long, and how much heat as being necessary anyways. This is my first time gluing PVC when it's been really cold out so I'm not really sure I fully understand the proper technique to heat/warm the fittings.
I think your suggestion that the torch may be volatizing the cement prematurely may be correct insofaras I know a couple of places the pipe scorched in a small spot or two from the torch flame which in my head means that area is hotter than the rest of the pipe we warmed up. If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time. -ME
I have used a heat gun and a heat blanket. Both work better than a torch for more even heat. The blanket (for warming freon tanks, from my HVAC days) is the best for even heat, but is slower than a heat gun. The heat blanket is just large enough to heat both ends of the pipe, about 6", at the same time. Takes maybe 4-5 min. per joint at 30 degrees.
I also use the heat gun to reheat a failed joint. When the joint is hot enough to be uncomfortable to touch, I slather on a big gob of glue and it sucks back into the joint just like solder on cu. pipe.
Dave
I also use the heat gun to reheat a failed joint. When the joint is hot enough to be uncomfortable to touch, I slather on a big gob of glue and it sucks back into the joint just like solder on cu. pipe.
This idea worked fantastic. We did it this AM, pressurized and the pressure held. THANKS A MILLION for the tip. I owe you a million for it, except, I don't have a million, or I wouldn't need to be doing this kind of work for a living :)If at first you don't succeed, try using a hammer next time...everything needs some extra persuasion from time to time. -ME
Thanks for the conformation.
I've posted that tip a few times, but have never had anyone reply if they tried it.
Dave
That is a good tip to know. Thanks.
That's a good one to know. I'm guessing it won't work so well on a joint that's already gotten wet, though.
People never lie so much as before an election, during a war, or after a hunt. --Otto von Bismarck
It won't work with water running through the pipe, but as long as there is no flow, it will. The first time I tried it was on a repair coupling placed in a 3" waste line. I must have missed a spot with the glue, or not been quick enough when sliding the repair coupling back and forth. I ended up with a small drip at one of the two couplings where I tied in an ejector pump. I made sure no one used any plumbing, and tried the heat gun/glue trick. It worked and save me a bunch of time and material rebuilding my screw up.
Over 2" drain size, I am only about 66% good with repair couplings. I always take the heat gun with me, for my 33% screw up rate.
Dave
By repair coupling I assume you mean a coupling with no center stop that is slid all the way onto one pipe and then halfway back onto the other. That would indeed be hard with a glued joint. I always use the Fernco rubber couplings for things like that. You can go to lunch halfway thru and come back to finish putting it on. I would have a 90% failure rate with glued pieces in that application--the glue grabs too fast to imagine it working.
Luckily for me I have not needed to get back up and running right away-so I have not needed to use heat.
Just thinking out loud here but have you thought about assembly in a shop (if possible) or what about the use of flanged or threaded fittings that are pre fabed in the shop and assembled in the field. I am not a big fan of PVC threads, but have had great success with the flanges (although those have not been buried).
Let me talk to my plumber and see what he suggests.
PVC must be clean, even a grain of sand in the joint can cause problems, this becomes worse as the temperature drops. I don't know what psi that you are using on your test, but PVC will not take too much pressure. How long are you waiting after the install to test the line? most cements have a set-up time. As the temprature drops PVC is prone to crack if people abuse it, a lot of times you won't notice it until its too late. Best that I can do with your prob. Have a good one.
"If all else fails, read the directions"
Don't twist back and forth, just twist in ONE direction as you're seating the joint. If you're lining up critical angles, mark each piece with a sharpie marker when you have them lined up in your test fit. After you prep the pieces with primer & glue, start the marks a quarter turn off line from each other twisting in one direction until the marks line up and hold for at least 30 seconds. Longer in cold weather.