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  1. #1
    Join Date
    Feb 2007
    Location
    Fairhope, AL
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    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)
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    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
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    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.
    The key to happiness is lower expectations.

    Don't pick the fly crap out of the pepper.

  4. #4
    Join Date
    Apr 2012
    Location
    So.Fl. & NYC
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    160
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    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
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    971
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    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
    Having sex is like playing cards, if you don't have a good partner, you better have a good hand. !!!!!!

  6. #6
    Join Date
    Apr 2012
    Location
    Paper Street Soap Company
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    2,309
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    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
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    1,606
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    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. Likes CHILLERSVCMAN liked this post
  9. #8
    Join Date
    Dec 2011
    Posts
    121
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    secure discharge line to the lifting bracket on top of compressor with some kind of clamp.

  10. #9
    Join Date
    Sep 2017
    Location
    Fremont, california
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    8
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    ga1279 is right. Most of the time those shipping bolts are the issue. Also adding a brace to the pipe helps

  11. #10
    Join Date
    Apr 2016
    Location
    Maryland
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    257
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    Is there a defect within the compressor ? Has a vibration analysis been performed and compared to factory specs ?

  12. #11
    Join Date
    Apr 2015
    Location
    west coast
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    21
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    I could assume the "T" you're referring to is where 2 compressor discharge lines are connected together? If so, get rid of the T and fab a manifold to provide laminar flow. Bullheading is not so nice...

  13. #12
    Join Date
    Nov 2016
    Location
    London
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    You have a vibration related issue

    Even the pipework that hasn't gone yet is on it's way out so completely replace it from the compressor right back to the condenser on both systems. In this situation I have found cracks on the inside of elbows because the vibration is concentrated. Therefore, anneal the pipe and use your bending tool to make the turn as this will give you a longer radius- spreading the vibration
    danARCICA by Maximus Chillers

    Chiller Sales, Maintenance and Repairs Maximus Chillers

  14. #13
    Join Date
    Nov 2016
    Location
    London
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    Forgot to mention: fit vertical and horizontal vibration eliminators too with the pipe supported on the far end
    danARCICA by Maximus Chillers

    Chiller Sales, Maintenance and Repairs Maximus Chillers

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