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Leaking Flange Connections

hvacfreak
hvacfreak Member Posts: 439
in THE MAIN WALL
Hello all ,

I have to deal with some leaking domestic water piping connections ( flanged 6 inch ) that involve schedule 80 pvc to iron body butterfly valves and also flat steel flanges. The bolt tension " appears " even , but I have not been able to stop these leaks with tightening the fasteners. I am thinking that what is needed is a metallic spacer that will provide a " surface " for a specific gasket for each side ( butterfly or paper on the steel side , rubber on the plastic ). Any thoughts appreciated.

Comments

  • bob young
    bob young Member Posts: 2,177
    TONY CONNER MIGHT HAVE THE ANSWER

    Tony might be the most experienced pipefitter on the forum.. if he sees this he might be the man to help you best. how about checking engineering dept. of flange vendor.
  • an old wrench puller
    an old wrench puller Member Posts: 73


    Usually, printed right on the PVC flange, is a torque Spec. Get a torque wrench and make sure they are all even. Also check carefully that the faces have not been damaged some how. Flange to butterfly, you should not need a gasket, the butterfly has a rubber seal built into it. Flange to flange, I would use a garlock gasket. You can measure carefully and see if you need a flange ring, but you shouldn’t. If you do.... you will need to use a gasket between the ring and the flange. These rings can be bought from your Victaulic or Groovelok supplier.
  • KevinCorr
    KevinCorr Member Posts: 106


    Yes, garlock are great, we use them on big oil steel pipe flanges but I have never used one on water. We usually use a rubber gasket on water lines. The garlock may be the best gasket, but I am just saying not the usual choice on water.
    In addition to the torque, you need to use a bolt pattern, that is the cris-cross sequence to bolt up evenly.
    Make sure the flanges are smooth and clean, not warped or gouged.

    http://www.millwrightmasters.com/School/bolt_pattern_torque.htm
  • hvacfreak
    hvacfreak Member Posts: 439
    thanks

    Thanks for the replies ( and great info ) on this . And yes , I'm sure that if these fitters torqued these connections in proper sequence and force there would be no problems at all. And now I get to re-work this piping with an occupied building...heck , it's a good day to be working is my new attitude about this stuff...lol.
  • Tony Conner_2
    Tony Conner_2 Member Posts: 443
    Thanks...

    ...for the nice words, bob. Most of the time, I feel like I've got a handful of answers that I've stumbled across, and all each one has done, is create 3 or 4 new questions for me. :) The more I know, the more I realize how much I DON'T know...

    Old wrench puller's answer is a good one - butterfly valves for water & air service have a rubber (or other plastic-type) liner in the body, that carries-out over the flange face. Some have an 'O' ring. Either way, I can't recall one needing a separate gasket.

    I think the valve will have to be dropped, and the liner/'O'ring checked. If shutting down a big domestic water service, I'd seriously consider having a replacement valve, and new nuts & bolts sitting on the floor when I did that. I might even want to have a grinder with a zip-cut in the truck. Very often, there's at least one fastener that just WILL NOT co-operate.

    Just a reminder to the guys doing this (I'm sure you already know) - it's really, really easy to over-torque bolts on PVC flanges, and crack them. Just when you thought that nothing else could possibly go wrong...
This discussion has been closed.

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