Support Analysis of Thermoplastic Pipe

[stanier]

If a plastic pipe is support by a beam how can one calculate the stress, deflections and moments in the pipe wall given the modulus, poissons ratio, physical dimensions of pipe and fluid? The concern is the approach needed to compute the local stresses at the support that may induce buckling.

I have been unable to find any code requirement that covers such a design criteria.

I presume it is much like a saddle support for a vessel or tank.

ANy good papers/software/books that cover this design requirement?

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[PrentP]

What's the polymer? Most are viscoelastic and undergo stress relaxation and creep under load. This is why you will not find design criteria you are looking for and I don't think you will be able to easily compute them.

Regards,

Peter P

 

[stanier]

The current material I am investigating is ABS. This is manufactured in Australia and the Far East up to DN1000. One has to establish the initial stress levels before one looks at the decay due to the phenomena of creep. I am wella ware of the manner that ABS creeps in that microcrazing occurs and relieves the stresses by this microstraining process. What I need to do is prove the worst case before the creep begins.

The problem exists for other materials that are used in piping above ground where the supports are spaced outside those recommended by the pipe manufacturer and the various standards.

Much the same problem in calculating the buckling stresses occurs in thin wall stainless steel piping. The stress analysis software like Caesar etc do not take into account the localised secondary stresses at supports.

ROark and Young in Ch12.7 gives some leads into research and test wrok. I was trawling the net looking for experience from others.

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