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Bend radii and Strength Knockdowns for tubing?

Bend radii and Strength Knockdowns for tubing?

Bend radii and Strength Knockdowns for tubing?

Hi all,

I am doing some notional design of a fluidic system. I am looking for some rule of thumb guidelines. I've been able to find min bend radii
- 4*OD no problem
- 2*OD can bend but may need internal guiding
- 1.5*OD probably need to bend hot
If anyone has anything more specific to materials, such as 304SS, 321SS, 347SS, Inco625, Inco718, Ti6Al-4V, Ti3Al-2.5V, etc I'd greatly appreciate it!

Secondly, I am looking for strength knockdowns. I imagine a knockdown will need to be applied in and near the bend due to the yielding that occurred, loss of ductility, and any residual stresses. Any references or general knowledge anyone has?


RE: Bend radii and Strength Knockdowns for tubing?

The book "Design of Piping Systems" originally published by the M.W. Kellogg company in 1941 has flexibility factors and stress intensification factors for pipe bends in Chapter 3. The same information probably occurs elsewhere, but this is a pretty good reference. I think there are pdfs of this floating around the internet.

Industry often uses specialized piping software, such as CAEPIPE.

RE: Bend radii and Strength Knockdowns for tubing?

Spacecraft Engineering is the wrong forum for a question like this... re-post to...

Pipelines, Piping and Fluid Mechanics engineering forum...

PS1. Any answer received from us will be strictly aerospace oriented. The thin wall tubing...and installs... are KISS designed based on rules/guidelines... then subjected to static and dynamic tests-test-test for durability.

Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

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