Cold Bends (20" x 25D)

[auzie5]

Anybody every build a NPS 20, Gr. 448 x 12.7mmWT cold bend (25D bend radius x 30 degrees). ERW line pipe. Internal mandrel is available. Satisfying the requirements of CSA Z245.11-14 (not too sure if ASME has a cold bend standard equivalent to ASME B16.49 for induction bends). Shop fabricated.

If so, aside from obvious problems related to ovality, wall thinning, ripples/wrinkles/buckles, did you run into any unexpected difficulties? Did you have to post bend heat treat to address residual stresses? Destructive tests performed to qualify the bend procedure would be used to establish the typical effects on mechanical properties at key locations on the bend resulting from the bending operation (ex: work hardening the extrados, Bauschinger Effect on the intrados, etc.).

Reference PFI Standard ES-24.

Thanks in advance for any input.

 

[LittleInch]

Not directly but I did once get an 8 inch 10D cold bend (seriously) which needed to be packed hard with sand during bending to prevent ripples. Passed all the required hardness tests etc.

You can get bends other than 40D, but they tend to be "specials" so not everyone is comfortable with it and the shoes will need to be specially made probably so they can get expensive....

You just need to find the right shop (I wouldn't try it in the field) then all should be OK.

Out of interest, why 25D?

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[BigInch]

30D is the minimum B31.4 cold bend radius for >= 20" pipe.
12" and smaller diameter is 18D.

 

[LittleInch]

Auzie, in your last two posts you haven't said where this is or what design code you're working to.

Can make quite a difference.

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