Need a coupling for SS tubing with same OD as the tubing 1

[KernOily]

Guys I need a way to screw together short sections of 1/2" or 3/4" SS instrument tubing, each section being 4' long or so, and subject to the following constraints:

1) The OD of the coupling or connector must be the same OD as the tubing, i.e. a standard pipe coupling or pipe collar won't work
2) The ID must be open to pass liquid

An example would be the way that a rifle cleaning rod screws together - it has a smooth and flush OD at the coupling. These are not hollow though so the example stops there.

The coupling must be the same OD as the tubing because the entire assembly must pass through a packing gland. Do any of you know if a coupling/connector like that is commercially available? The Swagelok people were no help.

I posted this in the Fluid Mech forum too so please forgive me for cross-posting. I wanted as many folks to see this as possible, though.

Thanks!
Pete



Thanks!
Pete

 

[Biggy]

Basically what you need is a 'barrel nipple' (threaded boths ends with the centre bored out), then just thread the id of the tube ends to suit. It would be a special fitting so you would need to test it, but a good fitter should be able to make one.

Or you could just weld it!

Biggy

 

[Harlow]

I think this is a job for a orbital welder provided the parts never need be desassembled. The problem you run into with threads is that even in .065 wall they would be awfull fine and subject to galding.