Re: Limit stop in Piping stress analysis

Dear Kaustubh

We think the same. However nothing is perfectly rigid. If a bit of flexibiity will overcome the problem, why not use it? A "stop" is never a stop; it always moves. The problem, as I see it, is to constrain the movement of a long, straight pipe to within limits. If springs on the "stops" will do it then why not? The calulations will show. However I totally agree that the use of three hard stops on a single straight run is a recipe for fracture. So build in some flexibility by springs or cables and counterweights.
By the way, there has been a lot of talk about coefficients of friction on flat shoes, using teflon and the like. If I have a pipe that simply has to move, I always use rollers. Do the sums and you will find the resistance is very small. And they cannot tip and jam.

I repeat I am not an expert on this subject, but I do like a debate, and thats what I bvelieve is part of the purpose of discussion groups.

Cheers

Steve McK

• Original Message ----- From: "KAUSTUBH JOSHI" <kvj@epc.ltindia.com> To: <PipingDesign@yahoogroups.com> Sent: Saturday, April 20, 2002 12:19 AM Subject: Re: [PipingDesign] Limit stop in Piping stress analysis

> Dear Steve,
>
> I did not get you exactly.
>
> What I think, it can not be possible with rigid restraints. In case of
rigid restraints the line would be overstressed due to not allowing thermal expansion. In case of multiple restrictions in a straight line, The supports can be sheared off or it can damage the pipe as well.
>
> With rigid supports, we can achieve the distribution of load
theoretically, as suggested by Tushar, but this system will be very very difficult to be implemented at site. And more over, the performance of the system could not be evaluated exactly due to deviations at site.
>
> I case of springs, being the low stiffness, supports absorb the thermal
expansion of the line and reduce the thermal stresses. But this certainly can not work with conventional rigid limit stops.
>
> Regards,
> Kaustubh
>
>
>
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Received on Fri Apr 19 08:55:00 2002