Pipe fastening

[vinay_kumar]

Hey guys,
I am a recent graduate and work with a sanitary fittings company. I am working on a project requiring to fasten a tube to a flat surface without welding. What other options do I have? I have attached the screenshot if it helps.
Thanks in advance!

 

[GrouchyStressedTensePoor]

What is the context of the design? Does fluid flow through the tube into the square part?

Generally you have

Shrink/press fit, probably not suitable given the geometry of the square piece.
Retaining rings/circlips/pins, you will have difficulty assembling.
Screw threads, however there does not appear to be enough material for the female threads.
Adhesives, probably not acceptable if welding isn't.
Rivets, not practical for the current joint geometry.

How flexible is that geometry? As drawn I don't really like that joint.

 

[LittleInch]

Materials, Size, pressure, etc are key factors also not provided.

Why no welding?

As drawn your options look pretty limited to me - glue.

could you screw it in place ( make the hole bigger?) or step the wall thickness to allow a thread?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[vinay_kumar]

Hey guys, thank you for the replies. Sorry for the delay in response. Yes, there is fluid flowing from the tube into the square part through the hole at 60 psi. It is to dissolve two liquids under pressure. Threading is not an option either because:
1. The fitting needs to be sanitary.
2. There is not enough material for female threads (0.035")

Welding is not possible because we are unable to get a clean weld on the inside of the square part. It messes up the flow channels and causes turbulence.
The geometry is not very flexible because the current design allows for even pressure drop and increased velocity in the square section allowing the liquid from the tube to dissolve properly.

I was wondering if there was a U-bolt type of set up possible? I can cut a groove for an o-ring and hold down the tube on the flat surface?

 

[racookpe1978]

A U-bolt (external clamp around the pipe) might work, but I'd go with a simpler fast-setting epoxy "glue" to create a fillet on both sides of the tube filling the two gaps between the round tube and flat surface. If you are creative with the applicator and extra glue, you'd seal the opening too.

 

[vinay_kumar]

I'll try both and update on the results. Thank you!

 

[bimr]

If the end result of joining these sections is required to be sanitary, I don't think glue would be acceptable. Sanitary piping must be:

• smooth;
• impervious;
• free of cracks and crevices;
• nonporous;
• nonabsorbent;
• non-­contaminating;
• inert;
• corrosion resistant;
• durable and maintenance free;
• nontoxic; and
• cleanable.

Rather than attempting to join these two pieces, you can use a metal 3D printing process to make the combined part out of metal.

Link[/Metal Prininglink]

 

[vinay_kumar]

Metal 3D printing sounds like a good idea. Are there any contacts in the United States I can talk to?

 

[bimr]

Here is a list of 3D metal printing companies:

Link to 3D Metal Printing

 

[vinay_kumar]

Thank you so much! This has given me enough ideas to get started on something concrete. Thank you everybody for the ideas.

 

[GrouchyStressedTensePoor]

So the internal geometry is fixed but you could potentially do something like machine a step into the pipe and slip a collar over the pipe that is then welded externally to the square section?

GSTP

Graduate Mechanical Design Engineer
UK

 

[vinay_kumar]

I thought about that and wasn't sure if that will be sanitary. There might be a crevice between the pipe and the step.

 

[vinay_kumar]

We decided that the approach had no effective result. We ended up welding the two up to sanitary standards because any other way and there would be a gap which would need to be filled in. The weld did damage the flow paths on the square section but we are working on machining that down.