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Pipe relining procedures questions.

Mark Eatherton
Mark Eatherton Member Posts: 5,863
in THE MAIN WALL
Wallies,



I went to look at a job today. It is a Spa (hot tub) heating system at a major hotel. This is the third time they've had to repair the flexible 2" lines going to the spa. The problem is that there is a 6" OC snowmelt system between the surface and the failed PVC pipe. Short of total demolition and complete replacement (ain't gonna happen this time of the year) or the possibility of locating the leak using any one of the methods I have available, I am considering relining the existing 2" pipe with one of the systems that are out there.



Any Wallies have any (good or bad) experience with these products and procedures?



TIA



ME

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Comments

  • SWEI
    SWEI Member Posts: 7,356
    two inch

    might preclude trenchless - I've never seen one that small, but maybe they exist.  Bursting the old pipe and replacing with welded HDPE provides the most reliable service IME, but of course temperatures are limited with HDPE. 
  • Larry Weingarten
    Larry Weingarten Member Posts: 3,676
    I'd be curious...

    ,,, to know why the PVC failed.  Did things shift and crack the pipe, bad glue joints, too much heat?  Can the cause be corrected?  Also, what flow really is needed?  Possibly 1.5" pipe could be slipped into the 2".  Use PEX,  It'll take more extreme conditions than PVC.  Yes, I know it's not really an answer to your question  :~)



    Yours,  Larry
  • SWEI
    SWEI Member Posts: 7,356
    trenchless heads

    Looks like there are now heads as small as 3/4" http://www.footagetools.com/brochures/wedge.htm
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,863
    Larry...

    I've not seen any samples of the failed tube, but my gut tells me its probably hydraulic erosion. I don't have enough gages to be able to calculate flow (yet) but based on the frequency of mid tube failures, I'm thinking excess velocity has something to do with it.



    Unfortunately, I'm striking out on finding someone who is capable and willing to pull a new liner through the existing tube. May have to resort to the good ol' jack hammer surgery for the time being...



    Thanks for chiming in.



    ME

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  • Larry Weingarten
    Larry Weingarten Member Posts: 3,676
    edited July 2012
    I've been looking around...

    ... for solid evidence of erosion in PVC using clean water and can't find it.  Mix in some sand and it's a different story.  It would be interesting to know if erosion is the culprit.  If so, the system is seriously over pumped!  The only limit to velocity in PVC seems to be hydraulic, water hammer type concerns.  Oops, the water was moving at 20 feet per second and a valve snapped shut!



    Jack hammer surgery! ... It's an image :~)



    Yours,  Larry



    ps.  Is the pipe laid in rocky soil?  Maybe it moves enough for sharp rocks to abrade through from the outside.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,863
    That was THEIR thought as well...

    And if it were a system that continually went through a large temperature swing, I'd concur. Except that it is a hot tub, and other than shut downs for repairs/maintenance, it stays at a constant temperature.



    The Chief Engineer said it appeared to have little slits. I forgot to mention, this is that flexible PVC, so it would have some decent turbulence. If I get a sample, I will dissect it and share it with all to see.



    Thanks for the input.



    ME

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