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  1. #1
    Join Date
    Feb 2007
    Location
    Fairhope, AL
    Posts
    17

    Air Cooled McQuay Scroll Discharge Line Failure

    I have had multiple discharge line crack failures on both circuits on this machine since installation approximately one year ago. It is a 90(?) ton machine serving several airhandlers in a HVAC situation. We have verified charge, repaired cracks, checked all bracing and mounts but the cracks keep happening. The crack has occurred at a tee every time.
    My question is to whether any service bulletins exist that address this problem.

  2. #2
    Join Date
    Jun 2010
    Location
    U.A. (upper Alabama)
    Posts
    856
    Quote Originally Posted by trozum View Post
    I have had multiple discharge line crack failures on both circuits on this machine since installation approximately one year ago. It is a 90(?) ton machine serving several airhandlers in a HVAC situation. We have verified charge, repaired cracks, checked all bracing and mounts but the cracks keep happening. The crack has occurred at a tee every time.
    My question is to whether any service bulletins exist that address this problem.
    Install the bolt on weights to discharge line, like the new Trane CGAM's use. LOL! But it would probably really work.

  3. #3
    Join Date
    Mar 2007
    Posts
    3,108
    There are two things that I know of that cause "cracks" in a discharge line. Overheated and/or overstressed pipe/fittings, and not enough mass in the piping to counteract the pulsation of the discharge gas.

    Weights might not be a bad idea.
    "There is no greater inequality than the equal treatment of unequals."

    -Thomas Jefferson

  4. #4
    Join Date
    Apr 2012
    Location
    So. Fl.
    Posts
    57
    Add vibration eliminators onto the discharge line to condenser barrel or if its air cooled,be sure to add stabilizing hanger to the outlet side of eliminator. We had this happen to several units in so.florida.

  5. #5
    Join Date
    Jan 2005
    Location
    Houston TX
    Posts
    874

    Compressor discharge line failures

    trozum- How are the compressors circuits mounted ? If they are all mounted on a flat plate that all four feet attach to, make sure the shipping bolts are removed. If they are mounted on 2 parallel base plates leave the shipping bolts in or re-install bolts in those openings, 4 bolts per compressor. The vibration of a running compressor to an idle compressor is what is causing your cracked discharge line.=GEO
    Once in a while everything falls into place and I am able to move forward, most of the time it just falls all over the place and I can't go anywhere-GEO

  6. #6
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
    Posts
    2,304
    Quote Originally Posted by trozum View Post
    I have had multiple discharge line crack failures on both circuits on this machine since installation approximately one year ago. It is a 90(?) ton machine serving several airhandlers in a HVAC situation. We have verified charge, repaired cracks, checked all bracing and mounts but the cracks keep happening. The crack has occurred at a tee every time.
    My question is to whether any service bulletins exist that address this problem.
    Ive had that issue with a couple of 20 ton ICMs with tandem scrolls,

    The compressor mounting hardware starts to back out and it causes excess vibration and cracks the discharge line.....at the T.

    Vibration is the primary cause of leaks on a discharge line on any machine.

    I had to add locktight because even with lock washers they would back out.

    Haven't had any issues since and that was 3 years ago.

  7. #7
    Join Date
    Feb 2003
    Location
    Wichita Ks
    Posts
    1,479
    most of the cracks I have found was caused by a compressor that had excessive vibration. I do not repair the tee I replace it.

  8. #8
    Join Date
    Dec 2011
    Posts
    107
    secure discharge line to the lifting bracket on top of compressor with some kind of clamp.

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