Article

Business & Economics :: Cost Engineering

November 1, 2009

# De-emphasize Capital Costs For Pipe Size Selection

## Focus more on mass flowrates, fluid densities and operating hours for real savings

Price volatility in industrial piping commodities, such as carbon steel, can complicate the selection of optimal pipe diameters at the start of a project. But while constantly changing capital costs will certainly affect optimal pipe diameter, plants can realize significant cost savings by focusing more on fluid densities, mass flowrates and hours of operation when selecting pipe sizes, and worrying less about varying commodities prices....

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Comments (2) for De-emphasize Capital Costs For Pipe Size Selection
1.
I read the article "De-emphasize Capital Costs For Pipe Size Selection" from the November 2009 edition. I followed the calculations in the article using an excel spreadsheet and I couldn't duplicate the results shown. The paper references Edgar, F.T., and Himmelblau, D.M. "Optimization of Chemical Processes," 2nd ed. McGraw-Hill, N.Y., 2001 (which I do not have a copy of) as the source of the following equation (equation 1). D(opt) = 0.9*[C0 + (C1*nu*gc)]^0.164 * m^0.459 x mu^0.033 * rho^-0.328. The graphs in figures 1 and 2 do not correspond to this equation (as I expect they should). I found that reversing the sign of the "0.164" exponent to "-0.164" yields the expected results. Respectfully, am I missing something or is there a typo in equation 1?
Posted by Jeff Lundberg on Wednesday, March 10, 2010 @ 06:18 PM
2.
In the original printing of this article, the addition signs in the following equations should have been division symbols: equations (1), (2A) and (2B). The version here is corrected
Posted by Editor on Wednesday, May 12, 2010 @ 07:33 PM

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