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deteriorated copper

webskier
webskier Member Posts: 8
in THE MAIN WALL
I have just discovered deteriorated .5" L soft copper in a 30 year old radiant system.  As far as I have discovered, there is only 3' of tubing at a 180 bend that has cracked in a spiral pattern along the tubing.  As I bent the tubing it broke easily.  Moving away from the bend in both directions I bent the tubing and it seemed normal: it would not break until kinked and repeatedly bent.  Inspecting the interior of the tubing there is no sign of corrosion. Anybody seen anything like this?  Is this tubing work-hardened at only one point or is there some metallurgical explanation for this? 





webskier

Comments

  • Unknown
    Unknown
    Seen-it many times,,,

    on potable type L too.



    Could be a combination of reasons, system contaminants, velocity issues, perhaps the operator of the tubing-machine in the factory fell asleep at the switch for awhile. :-)



    I would most definitely have your system flushed/cleaned, and monitor the PH level,,, that may help with any future perils.
  • Paul Pollets
    Paul Pollets Member Posts: 3,662
    Radiant type?

    How was the tubing installed? In a concrete slab, plaster ceiling, or under floor joists?  If the tubing was embedded, it's an easy answer.
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,858
    edited October 2009
    Could be multiple factors...

    In the "good ol' days", the engineers understood the coefficients of expansion of copper, and limited the length of the run to reduce potential stress on the tubing.At a 180 degree bend, if the bend was not bound by concrete, it could have been going through continuous expansion and contraction, which would cause the copper to become embrittled. Take a piece of soft copper and bend it back and forth many times, and it becomes brittle and will eventually break.The other factor working against you is hydraulic force, causing hydraulic erosion of the tubing due to continuous excessive velocity. That can generally be found by splitting the pipe laterally, and looking for U shape or V shaped marks inside the pipe where the bend is/was. Remember, horses always walk UP stream.To find out for sure, you can send a sample of the copper to the Copper Development Association, and they will diagnose it for you for free.ME

    There was an error rendering this rich post.

  • hot_rod
    hot_rod Member Posts: 23,184
    it may be an ongoing

    problem if there are other areas with 180 bends like that. copper can fail due to internal, external, or a combination of both conditions.



    Keep a plan B in mind for a system that starts to show failures like that.



    www.copper.org has plenty of info on copper and what can cause it to fail, good tip from Mark.



    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
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