Re: Pump Nozzle loads

From: <Christopher>
Date: Thu Jul 07 2005 - 10:43:00 EDT

On Jul 7, 2005, at 7:47 AM, Saha, Tanmoy wrote:

> Agreed. But sometimes or most of the times I found people deciding
> supporting and stress analyzing are not sufficiently experienced. And
> they think that they should provide guides and line stops only when
> they
> think that this is required from stress analysis point of view.
This is a very good point. You've probably also run into cases where boundary and support conditions are improper resulting in incorrect reaction forces. A client of mine ahd some problems with verifying that a light air to air heat exchanger could support some enormous piping loads. Turns out that the analyst had assumed that the heat exchanger was a fixed support. It took 3 or 4 exchanges of phone calls and letters to make the contractor understand what had happened, particularly that the assumption might have been conservative for the heat exchanger, but it was definitely un-conservative for the pipe: what had been assumed as two short spans was in fact much closer to one long span. I've also seen cases where only translational end fixity was applied at connections which were stiff enough to carry moments as well, resulting in wildly incorrect nozzle loading.

It's always a good idea to check nozzle loads carefully and sniff around to make sure that boundary conditions are realistic. Too many people use piping analysis software like a black box that does their thinking for them.

Christopher Wright P.E. |"They couldn't hit an elephant at <a href="/group/PipingDesign/post?postID=XzLnUNhT6dq5vIKLwQ7kkJIjcHcqZJsCm4OuWUaJ-kDztGDoWga3yeIfugRUMpgXmCRnlyXJ66IQ">chrisw@skypoint.com</a> | this distance" (last words of Gen.

.......................................| John Sedgwick, Spotsylvania

1864)
<a href="http://www.skypoint.com/~chrisw/">http://www.skypoint.com/~chrisw/</a> Received on Thu Jul 07 10:43:00 2005