Regarding friction in piping systems:
We have seen cases where long, large diameter pipe runs have experienced problems due to high friction loads. Certainly good designs, (i.e. properly located stops, loops and guides) can help mitigate this effect, but it seems that it should be the designers responsibility to determine when friction should be included in an analysis to be sure that collective loads do not cause problems.
We would anticipate that the majority of systems would not need to have friction included in an analysis, as many successfully operating pipe runs have already proven, but that, experience to the contrary not withstanding, an evaluation should be made of the potential impacts of friction on critical systems that might be susceptible to it's horizontal loading before the evaluation is started.
It would be my suspicion that the consulting company referred to below has designed and built numerous plants of the type that initiated the discussion in the first place, without needing to include friction, and make their claim based on a long and successful history of not including friction in the pipe stress analyses.
> Hello All,
>
> A few days ago, a world known consultancy & EPC company suggested us the
following:
>
> 1) While performing the static analysis (flexibility analysis) of the
piping systems, it is not necessary to consider the friction forces. The
friction forces are short time generated loads, and act on the system during
the thermal expansion. The friction forces diappears after the thermal
movement of the piping. That's why friction should be excluded from static
piping stress analysis (flexibility analysis).
>
> 2) There will be no friction at the guide side surfaces or the limit
stops. The friction will be there only for the resting supports.
>
> What are your views on these?
>
> Regards,
>
> Kaustubh
>
>
>
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Received on Mon Apr 21 05:06:00 2003
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