maximum sag before knuckling pipe (lifting 40m long pipe)

[samvanwesen]

I am trying to determine whether a +/- 40m long pipe on the floor (3'' SCH80 SS316) can be lifted vertically by a crane. The crane can only lift the pipe from one end. Will the pope knuckle? I am trying to find whether there are guidelines or empirical formulas describing this max bending phenomena.

THanks!

 

[LittleInch]

Its called buckling and there are various beam bending formula you can use - just google it or look for Euler buckling.

I can tell you now though that a 40m long 3" pipe will buckle under its own weight if lifted from one end, or get so close to the limit that no one will want to do it.

Also don't forget that at that sort of L/D, the pipe will start to "bounce" so you need to add some live load / shock loading onto whatever the static figures tell you.

http://www.eng-tips.com/viewthread.cfm?qid=193316

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[AGazo]

Try to check with FEA in horizonatl position. Select only gravity, material (without Force), don't forget to fix both end pipe. And you can see actual bend radius of long pipe. You can add approx. force for extremally case (dynamic lifting)

 

[simplemath2]

if you lifting point is above the CG, isn't pipe in tension?

 

[LittleInch]

Only if he pins the other end.

We really need a diagram to see what it's all about.

If enough axial force / tensions is applied you might get away with it but if you lift it vertically from the end or impose a compressive load on the end by having the crane lift it anything less than 90 degrees from the pipe, it will buckle.

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