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  • Oring seal over a split line between parts

    Discussion in 'The main mechanical design forum' started by GarethW, Apr 14, 2015.

    1. GarethW

      GarethW Chief Clicker Staff Member

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      Nasty little problem here and my back's against the wall in terms of options...

      I'm trying to incorporate an o-ring seal in an inconvenient area - over a split between two aluminum parts that are assembled together. Obviously the solution below is completely unacceptable because there would be ingress into the split.
      split seal 1.JPG
      Below the best solution I've got so far: Small rubber inserts (shown in red) inset into a recess that bridges the split line, thus preventing ingress. If it's done correctly the o-ring should seal against both the rubber and aluminium. Not ideal I know, but I've seen it done before effectively.

      split seal 2.JPG
      Any thoughts on this? Anyone got any better ideas?
       
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    3. Erich

      Erich Well-Known Member

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      Static seal?

      If so, you could put a small amount of RTV on the split and then install the O-ring.
       
    4. baneman

      baneman New Member

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      This is tough to reliably seal, but at low pressures you may have a chance.

      Some quick questions:

      What pressure are you sealing?
      Sealing fluid or gas?
      Pressure on both sides or just one?
       
    5. Steve6br

      Steve6br Member

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      You seem concerned about ingress into the joint but surely the fluid will get into the joint down the bore of the hole anyway?

      Could you use a top hat shaped insert to both align the hole accurately and provide a seal. A metallic insert could carry an o-ring groove in the face in the way you have suggested or be sealed using liquid sealer as suggested earlier?
       
    6. jheckert

      jheckert New Member

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      Hard to give a good answer without knowing the the application of this part but a simple remedy would be to machine both halves down a bit and use a thin gasket between them along with the o-ring. this will also prevent ingress through the seams in the bore. But like I said it is hard to give an answer not knowing the application/intended use of this part. Give more detail if possible because there are a few routes you can take here.
       
    7. Dave Archer

      Dave Archer Active Member

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      Are you trying to seal a liquid under pressure ?
      Any pressure will leak into the gap all the way down the bore and try to force the two alloy parts apart.

      A Design FAIL :eek:

      Back to the drawing board !!! Ha Ha..
       
    8. chris m

      chris m New Member

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      bore the hole out and put an insert a tube that has the your oring seal on the one end, or both ends if needed
       
    9. pramodkadam

      pramodkadam New Member

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      Hello GarethW,

      Did you try using liquid sealant between two parts and an Oring in Oring slot ?
      Is it not possible to add Oring material in One part ?

      Regards,
      Pramod

       
    10. GarethW

      GarethW Chief Clicker Staff Member

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      Thank you all for the replies and suggestions - greatly appreciated :)
      We've used a bit of RTV in conjuntion with the rubber inserts and it all seems to work nicely.

      It's only rain water at atmospheric pressure. Sealing to IP67

      Actually I'm not worried about this because there's a system of channels and gaskets within the assembly which prevent ingress

      So I think I'm OK with the chosen design (RTV in conjuntion with the rubber inserts). Not ideal, but it's our supplier's design (I'm just trying to "help out" a bit), and they will 100% test everything and provide guarantees. Not perfect, but in this case I'm happy.

      For your info, a good solution to this exact problem that I've seen before is to weld up the split after assembly and post-machine the oring groove. Bit costly, but a neat end-result.
       
    11. K.I.S.S.

      K.I.S.S. Well-Known Member

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      Hi Gareth,
      If you've got the volumes to justify it, check out a local U.K. Company - P2i - they've developed a excellent liquid repellant nano technology coating.
      K.I.S.S.
       

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