RE: Stress Analysis Issue

From: <Steve>
Date: Thu Oct 16 2003 - 05:04:00 EDT

Hi HY Tan

if the lines are long then the 12" line will have slightly less friction loss so pumping costs will be slightly less. You should look at the capex (cost to build) and opex(cost to run). Two 8" lines will cost more to build and to run than a single 12" line. However if one 8" line is already installed then things change. Two lines also have some "insurance" ; if one breaks, the other may still work, at reduced flow. For a new installation, 12" is most likely the best way.

Cheers

Steve McKenzie

-----Original Message-----
From: Tan Hian Yiam [mailto:hytan@ntpm.com.my] Sent: Thursday, October 16, 2003 4:46 PM To: <a href="/group/PipingDesign/post?postID=WnGSc_5kHJo1Eyf2Nub7U1N3P21yF3PLNkHq8OJAcLCEgi9qVd809g4bGmaJBSIsGGrY0l3gzv9mXFYLNcfEOnYllA">PipingDesign@yahoogroups.com</a> Subject: Re: [PipingDesign] Stress Analysis Issue

Hi,

If we pump the raw water 400 m3 per hr with two 8" GI pipe, is it the each 8" piping will carry the flow rate 400/2= 200 m3 per hr ???

Or better change to 12" pipe with single line ??

Thank you

HY Tan

• Original Message ----- From: Christopher Wright <chrisw@skypoint.com> To: ? <PipingDesign@yahoogroups.com> Sent: Saturday, June 28, 2003 12:15 AM Subject: Re: [PipingDesign] Stress Analysis Issue

> >Any suggestion on how to analyze the system?
> My first reaction is to retain me to do the analysis, but it's not all
> that difficult. The tower displaces in a certain direction taking one end
> of the pipe with it. Assume that the tower is much stiffer than the pipe
> (check this later) so the displacement of the pipe equals that of the
> tower. Find your strength of material book and look for the beam loading
> developed in guided bending (slope zero at both ends, but one end loaded.
> Find the formula for displacement and calculate the force corresponding
> to the tower displacement, then figure the remaining loads.
>
> This is a simple approach yielding a conservative force on the pump
> because it ignores the restraint imposed by the spring and the other pipe
> supports. If the load on the pump is way too high, you can do the problem
> manually with a little more work required to calculate the redundant
> reactions.
>
> Including the spring support and any others makes the pipe statically
> indeterminate, so you'll probably have to use one of the energy
> approaches to figure the redundant loads. My favorite is the 3 moment
> equation. It's a no-brainer with FEA, (not to imply that FEA doesn't
> require both experience and the brains to learn from it, just that it's
> an easy afternoon's work.)
>
> Christopher Wright P.E. |"They couldn't hit an elephant at
> chrisw@skypoint.com | this distance" (last words of Gen.
> ___________________________| John Sedgwick, Spotsylvania 1864)
> <a href="http://www.skypoint.com/~chrisw">http://www.skypoint.com/~chrisw</a>
>
>
>
>
>

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Information presented on this list is given as helpful advice, nonsense, carefully-considered calulation or any combination of the above. The intent is to spark discussion and encourage knowledge-sharing amongst professionals. If you blow yourself up by doing stuff remotely described by info gleaned from reading this list, you are an idiot.

Your use of Yahoo! Groups is subject to <a href="http://docs.yahoo.com/info/terms/">http://docs.yahoo.com/info/terms/</a> Received on Thu Oct 16 05:04:00 2003