Induction Bend Thinning Allowance ASME B31.4/B31.8/B16.9

[Hayms]

Hello,

Is there a spec/manual with a method to calculate the maximum bending thinning at the extrados for larger radius induction bends (10D,20D) for liquid or gas lines?
ASME B16.49 Section 12.3 references a 10% thinning. But wouldn't a 6D induction bend have a higher thinning allowance then a 10D Induction Bend?

Details:
NPS 20, API 5L, X65 Pipe MOT: 100F
Design Pressure 1300 psi 0.5 inch WT

Thank you.

 

[LittleInch]

BS PD 8010 quotes bend thinning as 50 divided by n+1, where n is D of the radius.

So a 5D bend is just over 8%.

No idea where 10% comes from.

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[LittleInch]

"Normal" 40D bends don't normally need any thicker pipe.

10D and 20D is not normally seen.

Usually 3 or 5 induction or 40D cold bends.

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

 

[SJones]

Formula in ISO 15590-1 (probably the same as BS 8010)?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.