I'm developing a 3d project using AutoCAD 2013 and I would like to request ideas for a specific problem. It is not for a commercial project.

It is about how to connect two hollow plastic pipes using a "quarter turn" design.

The only thing that'll run inside them is non-pressurized water.

Is there a way to implement a locking mechanism inside the thickness of the pipes?

All measurements are available next to the picture, in millimeters.

The goal would be to:

-- Connect them without using any tools
-- Be easy to connect and disconnect
-- Have no water leakage outside of the pipes
-- Have a clean design (nothing hanging from the inside or from the outside)
-- Have the locking mechanism implemented inside the thickness of the pipes, at their extremities, 10mm max width, no plastic doohickey on the outside to lock or unlock

I keep trying to find a way to implement the following design but i'm just not visualizing in my mind how the mechanism would work.


-- Picture:

enter image description here

Any ideas would be appreciated.

Thanks in advance,


  • No feasible way with the constraints that you place on the requirements.
    – Michael Karas
    May 21 '15 at 8:23
  • 1
    Look at common PVC fittings. You'll notice that where the pipes mate, the diameter of the pipe is increased to allow one pipe to fit into the other. Without at least this level of diameter increase, you'll likely never find a way to mate the pipes without using an additional fitting. The pipes have to slide past each other in some way, but reducing the wall thickness to allow this would likely weaken the pipe too much.
    – Tester101
    May 21 '15 at 11:14
  • Thank you both for your comments. I guess I'm demanding too much. I'll find a way to connect the pipes using a full turn design, just like a plastic cap in a coke bottle. I'll ask to have them machined in a plastics factory.
    – thiago
    May 21 '15 at 14:25

To rephrase:

Is there a way to make two pipes join together in an removable way that would be no more than 10mm thick with nothing inside or outside the extended planes of the existing pipes in a way that is water tight?


BTW- the image in the link provided is for a key lock for desk drawers and the like.

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