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Thread: compression fitting too tight?

  1. #1
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    compression fitting too tight?

    is it possible to overtighten a compression fitting? i found with my tubing (tygon s-50-HL) that after a while (ie a half-hour or so, while i was doing up other things) i could screw the collars down further, basically to the point that they're all more or less screwed all the way in. it wasn't easy to do mind, i used rubber gloves to get a proper grip.

    been leak testing and there seem to be no problems.

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    I used a wrench on my barbs

    I tightened mine by hand but 1 leaked so I got the wrench out and tightened them a little more.

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    Xtreme Cruncher pwolfe's Avatar
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    I hand tighten with kung-fu grip

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    Xtreme Cruncher SoulsCollective's Avatar
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    Yes, it's definitely possible to over-tighten. If compression fittings are tightened too much they can start to cut into the tubing, which is obviously not good and will cause you problems further down the track. You should never have to use any kind of tools to tighten your fittings, screw them down finger-tight and then maybe "kung-fu grip" ( ) them another half-turn.
    Quote Originally Posted by iNoXiouZ View Post
    I used a wrench on my barbs

    I tightened mine by hand but 1 leaked so I got the wrench out and tightened them a little more.
    I suspect your leak was from the base of the fitting not being properly tightened down (and thus your wrenching the collar also secured the base), not from the collar - in order for a compression to leak from the barb/collar section the tubing would need to be either the wrong size, and therefore far too loose on the barb, or not pushed far enough down the barb. The collar is there simply to prevent the tubing from working off the barb, not to ensure a seal.
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    It was just a standard barb (not a compression fitting) in a XSPC Res top, the barb goes in at a slight angle and so I either needed to tighten it more or get some more rubber gromets

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    Xtreme Cruncher SoulsCollective's Avatar
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    Quote Originally Posted by iNoXiouZ View Post
    It was just a standard barb (not a compression fitting) in a XSPC Res top, the barb goes in at a slight angle and so I either needed to tighten it more or get some more rubber gromets
    I see.

    I'm a little curious as to why you're posting this in a thread about whether you can over-tighten compressions, then
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  7. #7
    Xtreme Addict rge's Avatar
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    Whether you use barbs with clamps or compression fittings, over time the tubing will be compressed, and allow further tightening. I dont know if its necessary to tighten any further, and I dont, just an observation.

    I use 3/8 5/8 ie thicker tubing with compression fittings for quite a while, and all of mine are always tightened all the way down, and none of mine have cut into tubing...maybe with the thinner wall tubing its a concern, or maybe depends on the particular brand of compression fittings. I can tighten most of mine all the way down by hand, but it gets tiring, so I use rubber tipped pliers and just tighten all way down. On other side, may not be necessary, but I have never had any leaks, so will continue to do it that way.

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    Quote Originally Posted by SoulsCollective View Post
    I see.

    I'm a little curious as to why you're posting this in a thread about whether you can over-tighten compressions, then
    Just pointing out that if tightening by hand isn't enough then you could use a wrench.

  9. #9
    Xtreme Cruncher SoulsCollective's Avatar
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    Except that a straight barb is an entirely different thing than a compression fitting.
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    Quote Originally Posted by SoulsCollective View Post
    Except that a straight barb is an entirely different thing than a compression fitting.
    Ok I know the differences between a barb and a compression, however my point is still valid as you could use tools to tighten either a barb or a compression fitting.

  11. #11
    Xtreme Cruncher SoulsCollective's Avatar
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    Yes, you could, in the same way that you could use a blowtorch to both light a candle and repair your car. The use of the tool will have entirely different consequences depending on the specific application - in this case, using a wrench to tighten the collar of a compression fitting has a not insignificant chance of puncturing your tubing, causing system leaks.
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  12. #12
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    Quote Originally Posted by SoulsCollective View Post
    Yes, you could, in the same way that you could use a blowtorch to both light a candle and repair your car. The use of the tool will have entirely different consequences depending on the specific application - in this case, using a wrench to tighten the collar of a compression fitting has a not insignificant chance of puncturing your tubing, causing system leaks.
    I'm talking about tightening the fitting to say a GPU block, not tightening the compression on the tubing, Sorry if I wasn't clear.

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  13. #13
    Xtreme Member Philwong's Avatar
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    Quote Originally Posted by rge View Post
    Whether you use barbs with clamps or compression fittings, over time the tubing will be compressed, and allow further tightening. I dont know if its necessary to tighten any further, and I dont, just an observation.

    I use 3/8 5/8 ie thicker tubing with compression fittings for quite a while, and all of mine are always tightened all the way down, and none of mine have cut into tubing...maybe with the thinner wall tubing its a concern, or maybe depends on the particular brand of compression fittings. I can tighten most of mine all the way down by hand, but it gets tiring, so I use rubber tipped pliers and just tighten all way down. On other side, may not be necessary, but I have never had any leaks, so will continue to do it that way.
    I use 1/2" OD tubes on 1/2" BP compressions tightened all the way down, too. So far so good, no leak, cut or whatsoever.

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