Pipe Bend with Internal Pressure
Pipe Bend with Internal Pressure
(OP)
I have performed stress analysis of aircraft systems previously where I have utilized Boeing Design Manual BDM-6845, Piping and Ducting. In it, it accounts for a stress factor on the hoop stress at tube bends, Section 3.5, (2R+rsinθ)/2/(R+rsinθ). I am now in need of an open source reference for this factor. I was wondering if anyone could please assist and point me in the direction of such a reference if one is known?
Thanks.
Thanks.
RE: Pipe Bend with Internal Pressure
next obvious ... did you look in Roark ? there's a section on piping.
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RE: Pipe Bend with Internal Pressure
or fake out the expression ...
x = r/R, k = (1+x/2*sin(alpha))/(1+x*sin(alpha))
another day in paradise, or is paradise one day closer ?
RE: Pipe Bend with Internal Pressure
But I've been designing pipes for decades and never seen this before. Is it some version of the bourdon effect?
https://www.eng-tips.com/viewthread.cfm?qid=6924
Look it up but seems to be a similar equation.
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RE: Pipe Bend with Internal Pressure
RE: Pipe Bend with Internal Pressure
"Internal pressure can affect the pipe bend or elbow in 2 ways. The Bourdon effect describes the tendency for the pipe bend to "open" under internal pressure and "close" under external pressure. The reason is as described by Electricpete. The other effect is the "stiffening" of pipe bends and elbows as internal pressure is increased. The stiffening results from the internal pressure resisting the "ovalization" of the cross section that normally occurs when a bending moment is applied to the bend. One or both of these effects can occur in large diameter pipe with large D/t ratios. Reference B31.3, Appendix D, Table D300 and note (7). If you have piping systems of moderate diameter but are designing to B31.3, Chapter IX (high pressure - Class 2500 or higher) you will want to consider these effects. Good pipe stress computer programs (e.g., Caesar II) will give you the option of "toggling" these effects off or on."
googling "bourdon effect" gets hits ... more threads on Eng-Tips !
I don't know what "Reference B31.3, Appendix D, Table D300 and note (7)." refers to.
another reference to Ceasar, so there may be something there ?
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RE: Pipe Bend with Internal Pressure
RE: Pipe Bend with Internal Pressure
I suspect Ceasar user manual may define this too ?
another day in paradise, or is paradise one day closer ?
RE: Pipe Bend with Internal Pressure