Pipe Deflection During Lifting
Pipe Deflection During Lifting
(OP)
Hello,
I was asked to figure out the amount of deflection in a pipe for two different lift contact points - with the majority of the load lift from the center and then with the load lifted from one end.
Originally I thought this would be a quick calculation where I could pull the equations off beam deflection tables, however when I did so the deflections I got were somewhat higher than I expected.
My parameters are: 50' length (yes, quite the long length!), 8" sched 40 steel pipe. It will either be lifted from one edge, or the middle (another strange thing, since I'm sure it would be too cumbersome to actually lift a 50' long pipe from only the middle).
From my understanding, the beam tables show either cantilevered beams or fixed-fixed beams. So is it possible to correlate these criteria to the fact that the beam is technically not fixed at any point?
Thanks!
Annette
I was asked to figure out the amount of deflection in a pipe for two different lift contact points - with the majority of the load lift from the center and then with the load lifted from one end.
Originally I thought this would be a quick calculation where I could pull the equations off beam deflection tables, however when I did so the deflections I got were somewhat higher than I expected.
My parameters are: 50' length (yes, quite the long length!), 8" sched 40 steel pipe. It will either be lifted from one edge, or the middle (another strange thing, since I'm sure it would be too cumbersome to actually lift a 50' long pipe from only the middle).
From my understanding, the beam tables show either cantilevered beams or fixed-fixed beams. So is it possible to correlate these criteria to the fact that the beam is technically not fixed at any point?
Thanks!
Annette





RE: Pipe Deflection During Lifting
<BTW I think lifting pipe from the middle or one end is an excellent way to get somebody hurt.>
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RE: Pipe Deflection During Lifting
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RE: Pipe Deflection During Lifting
Assuming rho = 7850kg.m^3 and E = 192363 MPa ....
d = 5wl^4/(384EI) so d is approx 50mm at midspan
Lifted at the centre it's the same as two simple catilevers back to back since rotation at the centre will be zero.
d = wl^4/(8EI) and end deflections will be approx 30mm
Beware of local stresses particularly in the second case ... buckling may occur at the lift point.
RE: Pipe Deflection During Lifting
You got your post in whilst I was writing mine.
The equation you quoted is for a fixed end UDL beam, which this is not. Pinned ends would be more appropriate without moment restraint, so (5x) the deflection. Note that my 'w' is unit weight so l^4 is needed.
RE: Pipe Deflection During Lifting
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RE: Pipe Deflection During Lifting
C2it, I did the same thing as your first formula before and it did give me a more reasonable number. So I will stick with that! Thanks! :)
RE: Pipe Deflection During Lifting
This is realistic and will increase your deflection and stresses.
NozzleTwister
Houston, Texas
RE: Pipe Deflection During Lifting
For lifting from the ends, assume pinned ends with uniform load. You'd also have some compression, which probably wouldn't drastically affect deflection in this case.
8" steel pipe doesn't normally suffer from local buckling, so it can have a fair bit of deflection and still be okay.
RE: Pipe Deflection During Lifting
That dangerous condition would be analyized as an inverted "T" support.
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RE: Pipe Deflection During Lifting
RE: Pipe Deflection During Lifting