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2-inch Pipeline deflection

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npao

Civil/Environmental
Sep 19, 2012
3
Can someone please help me with this question? I have been trying to solve it but I have not been succesful. [ponder]

What is the maximum deflection of 2-inch pipe in number of degrees (maximum deflection in number of degrees that the longitudinal axis of the pipe may be permanently deflected in any length along the pipe axis equal to the diameter of the pipe)?

Pipe description:
Carbon Steel, Schedule 80, wall thickness 0.218”, MAOP 2500 psig.

Thank you in advance!
 
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Hi npao:

Deflection as I know is a dimension, not angle, you can calculate the deflection angle when you know deflection and the span of pipe. Now, the angle = arctan (deflection)/(span/2). For max defelction you have some criterias, for power piping B31.1 0.1 inches & for process piping as Kellog 0.5 in to 1.0 inches.

B regards,

LFC
 
Thank you for the response. I apologize for the lack of clarity in the question, I will try to better phrase it.

This question came about a project where 40' lengths of pipe is being welded together, and now that the contractor is getting ready to lay it at the bottom of the ditch. 2" welded pipe is flexible however it will have stress areas because they did not manually bend the pipe.

So I now need to figure out how many degrees can the pipe flex (self bend) before is requires mechanical bending?




 
Now I understand your question, so it is neccessary to calculate the stress for a specific condition, like span between footholds, allowable stress can be assumed like 2750 psi as Kellogg, and then calculate the deflection nad then angle of deflection. In an excel you can make fast and easy the calculus. It is neccessary to iterate the result.


B. Regards
 
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