Bend radius for stainless steel

[gravitate]

What is the minumum bend radius for stainless steel? The wall thickness is 3mm and the ND is 47mm
I have been told that 1.5 can not be done

 

[gravitate]

I forgot to mention it is Austenitic stainless steel.

 

[berkshire]

You could do 1.5 D as an inside bend by filling the tube , or on retreating mandril bender.
1.5 D as a centerline bend would be tough. You may want to use a fitting there.
B.E.

The good engineer does not need to memorize every formula; he just needs to know where he can find them when he needs them. Old professor

 

[BigInch]

You would have to do that hot.
Are you intending to bend hot or cold?

"People will work for you with blood and sweat and tears if they work for what they believe in......" - Simon Sinek

 

[desertfox]

This link might help:-

http://www.iac-intl.com/parts/PB103001r2.pdf

desertfox

 

[gravitate]

Hi thinks for the replies. To be honest it's is in a design and I am trying to justify that it is ok and will be safe.

 

[Oldhydroman]

It's only a thought, and there's plenty of experts in this particular forum that might comment again, but have you considered that the loss of wall thickness on the outside of such a tight bend might cause a significant reduction on the pressure rating?

If your bender/mandrel set-up manages to maintain the outside wall thickness, then are you going to get localized buckling on the inside of the bend - the stresses of which also reduce the pressure rating? In a nutshell: whatever method you choose to form this bend, what will it do to the pressure rating? Or is the tube not pressurized?

DOL

 

[GearsNsparks]

Listen to BigInch. You can do it, but you will need some heat. Make sure your extrados isn't thinner than your minimum wall thickness from your pressure design.

 

[gravitate]

Thanks. I have got my hands on a copy of ASME B31.3. How can I check the minimum wall thickness?

 

[jtseng123]

304.2

 

[Korichnevijgigant]

Usually wall thinnning while forming elbows in austenitic stainless isnt a huge issue if its a cold bend.

300 series stainless steel work hardens during forming; therefore the material strength will increase when compared to a straight line of the same material