David,
I came across a paper yesterday by PFRA ARAP named "water conveyance with Syphons. This paper covers buckling issues. In addition Austrlian Standard As 2566.1 covers the design of Buried Flexible Pipelines. It gives the proceedures for design where vacuum conditions occur in conjunction with live and dead loads. It can be downloaded from www.standards.com.au for a small cost.
You might also try the US Army website. They have many very good articles on the design of pipelines.
Try also the plastic pipe Institute where you can access technical notes and papers. You can discover the properties of PE here. Beware there are various grades with different valuse. If you can tfind the data here contact Driscopipe in the USA or Borealis in Europe for data.
One thing to bear in mind when designing for buckling with PE is the out of roundness that you start with. Timoshenko and Roark books are the classic texts on buckling from external loads. If the pipe is elliptical before you start the propensity to buckle increases drammatically.
Geoff Stone
--- Wilkonet <wilkonet@yahoo.com> wrote:
<HR>
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<tt>
Hi Everyone,
I've recently started my first main job as a trainee mechanical engineer. One of the first problems ive came across is to modify a piping system for supply water to a power plant. The material is hdpe, 450mm dia, 7400m long. The is currently insufficient flow so a modification is needed. My modification means that the change in elevation from pump to dam is now -8m instead of previously 8m. (the pipe would be re ruited)This in theory would give suffiecent flow. However I have been warned that if the pump is turned off this could cause a vaccuum to be formed and the pipeline to be crushed.
I have been searching through the net to try and find some information on designing pipe systems but have failed to find anything to give me information on a system which pumps 'down hill'.
It would be great if anybody could give me some advice or any information which would halp me in my problem.
Regards,
David Wilkinson
</tt>
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