Bend Flexibility Factor with External Pressure

[FX103]

Hi all,

ASME B31.4 gives a correction factor for the flexibility factor for bends when those are subject to an internal pressure (even if it doesn't specifically say "internal" pressure I deduce it from the fact that ASME B31.4 is mainly a piping code). Internal pressure decreases the flexibility of the bend or in other words increase the stiffness. My question is: would it work the other way round when the bend is subject to a significant external overpressure felt for example by an empty pipe in deep water?

Many thanks

 

[BigInch]

Yes. External pressure will collapse a pipe, if it rises above the theoretical collapse pressure. Collapse pressure is highly dependent on the initial ovalization of the pipe.

http://www.pipingoffice.com/pdf/ExtP.pdf

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