1

I have to mate two sections of something that could be reasonably approximated by a tube, though the material is stainless steel, and the cross-section is very non-circular, so I cannot use an o-ring. The walls are thin and the exterior must remain flush, so a flange/gasket is also out.

Are there established methods for pressure sealed mating of non-circular cross-sections?

Worth mentioning I will be able to compress the two pieces via internal screws.

The diagram below shows some examples of what I might expect appropriate solutions may look like:

Diagrams of possible mating geometries

The left most is how the parts are now, with a flat mating surface. This would provide a terrible seal. The right two are possible solutions, but I would really like some precedence to justify my design.

Any guidance or references would be greatly appreciated.

EDIT: To address the comments, the wall thickness is 1/32". I will post a picture of the cross section below. Only the channels are pressurized against near vacuum in the internal volume and in the exterior. The gauge would be at max ~10 bar. There is no limitation on roughness of the channels. I cannot weld them because being able to open and close the part is a critical design feature. Gaseous Nitrogen is the fluid.

Sealing between the channels is not necessary.

Cross-section of part

A McKelvy
  • 121
  • 2
  • 3
    o-rings can adapt to non circular shapes, as long as you give the groove shape several o-ring-width's of radius. rectangular o-ring-like gaskets exist too. face seals can be any shape if you have axial force and something to contain the seal in place laterally... can you show thickness, pressure/ vacuum range, and more part detail regarding how it's non circular? – Pete W Oct 26 '21 at 22:18
  • a sleeve around it or a non-standard 3-D gasket – Tiger Guy Oct 26 '21 at 23:18
  • Copper gasket___ – RC_23 Oct 27 '21 at 01:25
  • 2
    So weld it. Stainless can be welded. – Solar Mike Oct 27 '21 at 05:01
  • Adding to PeteW's comment: first, you seem to claim there's not enough thickness for a gland, so why do you think a shaped O-ring (easily obtained from major manufacturers could be used? – Carl Witthoft Oct 28 '21 at 13:32
  • In any case, you can't get useful advice unless we know things like the pressure levels involved, allowable non-smoothness (mating ridge, e.g.) on the inside, which affects the Reynolds Number, types of fluids being transported, etc. **and wall thickness** – Carl Witthoft Oct 28 '21 at 13:34
  • It is very difficult to visualize the mating surface giving the images you've posted. However you can seal almost anything by adding a smooth surface on one part, and a matching o-ring groove on the opposite part. The groove path does not need to be circular, it just need to maintain a certain minimum bend radius. You can buy o-ring material on a spool and glue the ends together to make an o-ring of any length. – Drew Oct 31 '21 at 05:34
  • If you can provide strong, and even pressure to the mating parts, it is possible to create an airtight seal with metal on metal. One part would have a smooth surface, and the other would have very small ridge that squishes slightly as the parts are clamped together (like an o-ring). – Drew Oct 31 '21 at 05:37

0 Answers0