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How do I repair PVC?

Discussion in 'Irrigation' started by jcom, Jun 7, 2005.

  1. DanaMac

    DanaMac LawnSite Fanatic
    Messages: 13,187

    Of the 3 pieces you are all talking about, here is my order of which leak the most often on main lines or otherwise

    1. Compression repair fittings
    2. Unions
    3. Telescoping slip fixes

    I personally use the slip fixes, and on mainline I get it extended out as far as possible. Now the thing is, any of them will do the job properly and probably not leak. But, they all have to be installed PROPERLY or they will leak. I don't like having any extra thread joints in a mainline if possible which is why I use the slip fixes. But I don't see anything over 1.5" pipe.
  2. SprinklerGuy

    SprinklerGuy LawnSite Bronze Member
    Messages: 1,778

    I used many compression couplings in the golf course back in the late 80's myself. We installed thrust blocks to prevent the pipes from moving. I only worked there 7 years so I can't really say if it lasted or not.

    However...I wouldn't use a compression coupling in a mainline at a house that I serviced. I also don't think I would use a union....but I guess if I didn't have a choice I might.

    Personally, I have done many repairs with four 90 degree elbows. Go ahead flame me....

    I have used slip fixes in pvc and never had a problem unless I didn't get it fully extended....

    I have also used the expandable slip fixes in poly....and I plan to make them better and make millions of dollars....(how do you type an Austin Powers type laugh?)
  3. Wet_Boots

    Wet_Boots LawnSite Fanatic
    Messages: 50,267

    How many continuous-pressure-rated telescoping fittings can you find? Count with me. How about zero? Doesn't mean you can't get away with using one in that application, but why bother trying? Getting a leak from a fully tightened Schedule 80 union is something I've never seen. That would take a defective O-ring from the very start. And since the threads on the tightening nut are the easy-to-work-with acme type, failing to fully tighten one means that Michael Jackson could beat you at arm-wrestling.

    The issue of O-ring failure on telescoping fittings has been addressed by Dawn Industries. They have introduced all-glued repair fittings they call <a href=http://www.irrigation.ca/Products/Repairs/kwikrepair.htm>KwikRepair</a>
  4. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Messages: 2,697

    Hey SprinklerGuy (or any others with golf course irrigation experience), have you ever seen a couple hundred feet of 3" or 4" pipe come snaking out of the ground?? Or the hat of a female golfer get blown off her head and into the rough when a DR91 with 7/16" nozzles nails her in the head with a 90 gpm stream at 125 psi?? :D
  5. bicmudpuppy

    bicmudpuppy LawnSite Silver Member
    Messages: 2,781

    I've had the hide removed from my backside from being to slow w/ a valve in head at 160psi service pressure. Does that count? and about flow-spans (slip fixes) on large pipe, you better make SURE you are working w/ a long straight run of pipe w/ no elboe just past where you dug. Things get ugly when 4" PVC is allowed to move. I've used 3 and 4" flow-span repairs w/ success, but if I've got to put money on it, mechanical repair couplings w/ locks are the only way to go. A union is great IF you can be that perfect. In my experience, something always moves just a touch and if you can't draw up the slack, that union is going to leak. Now, if you can work fast and get the slack from the glue side before everything sets up......great. But 4" pvc on a 100degree day sets up REAL fast.
  6. Instant Rain

    Instant Rain LawnSite Member
    Messages: 54

    She's lucky it was just her hat because it could have taken her eye out of her head.

    I have seen pvc compression fittings and slip fixes as large as 6 inches. I would never use pvc on a large repair with high pressure. The process for making fittings is different from that of making pipe. fittings are molded. Pipe is extruded. For large repairs I use metal gasketed fittings. there are some available now that can restrain the pipe eliminating the need for thrust blocks.


    Here is my take on repair couplings and why they sometimes fail after being installed.


    Most of the failed repairs i have seen with slip fixes are from the slip fix not being fully extended when installed. A slip-fix not fully extended when installed is basically a hydraulic ram. Installed on a length of pipe under constant pressure this is usually not a problem. Installed near a tee or 90 especially on a lateral and its only a matter of time before the fitting gives out.
    Also you must be careful when putting primer on a slip-fix not to let any primer come in contact with the o-ring.


    These are great. Who ever invented them was a genius. I don't like to use them on repairs because there is no margin for error when measuring for something like that. But i do use them on every valve in every new install.
    This allows me to give the factory warranty on those valves. If I get stuck with a bad batch they can easily be replaced. I have replaced a two inch valve in as little as six minutes! Also I only install valves with a ten year warranty.

    Compression couplings.

    These must be installed with very little space between the pipe on each end of the repair. Also they must be installed so the split in the pipe is in the middle of the coupling. I don't like to use them on anything smaller than three inches. A benefit with these is there is no curing time what so ever. Also they are the only type of fitting that will reliably hold under deflection as long as they are blocked on the side they are deflecting to.
  7. Instant Rain

    Instant Rain LawnSite Member
    Messages: 54

    Here is a repair I did a few years ago. I'm not proud of it but there are many things in it that show exactly what not to do.

    The pipe is 6 inch sch40 the tee is glued in with a reducer to 4 inches sch40
    the 90s are glued in. and the blue pipe is gasketed 4inch class 200.

    This was a reroute for new campus being placed on an old golf course
    some or the gate valves were dated 1969. alot of iron and cement asbestos pipe. an asbestos removal company installed the six inch mainline after
    removing the old pipe.

    this picture was taken 2 months before the cement bag used as a thrust block in the 4inch blue pipe failed the pipe pushed snaped the 90 and peices of it were found 200 feet away.

    Attached Files:

  8. jcom

    jcom LawnSite Senior Member
    Messages: 791

    I used a slip fix fully extended and appears to work very well. Time will tell.

    Thanks for all the info.

    John :rolleyes:
  9. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Messages: 2,697

    Heehee, I've had my share of removing the valve assemblies from valve-in-head sprinklers that are under pressure. It's hard to believe how quick you can turn a green, tee, or fairway into a water hazard. :waving:
  10. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Messages: 2,697

    Oh, believe me, I know the damage that can be done. Later that day when I was in the clubhouse, a few of the old gents congratulated me for getting her wet. She had a reputation as a snobby rich b**ch and they said it couldn't have happened to a better person. I told them that it was purely an accident and there was no way I could of even planned that to happen like it did. They didn't believe me.... :angel:

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