Pipe size optimum

The drill string design is to determine an optimum combination of drill pipe sizes and steel grades for the lowest cost of string or the lowest total load (in... 

Nolte, C. B. (1978) Optimum Pipe Size Selection (Trans. Tech. Publications). 

In a chemical plant the capital investment in process piping is in the range of 25-40% of the total plant investment, and the power consumption for pumping, which depends on the line size, is a substantial fraction of the total cost of utilities. Accordingly, economic optimization of pipe size is a necessary aspect of plant design. As the diameter of a line increases, its cost goes up but is accompanied by decreases in consumption of utilities and costs of pumps and drivers because of reduced friction. Somewhere there is an optimum balance between operating cost and annual capital cost. 

Economic Optimum Pipe Size for Pumping Hot Oil with a Motor or Turbine Drive... 

The procedure for optimum selection of insulation thicknesses is exemplified by Happel and Jordan [Chem. Process Economics, 380 (1975)]. They take into account the costs of insulation and fuel, payout time, and some minor factors. Although their costs of fuel are off by a factor of 10 or more, their conclusions have some validity if it is recognized that material costs likewise have gone up by roughly the same factor. They conclude that with energy cost of 2.5/million Btu (adjusted by a factor of 10), a payout time of 2 years, for pipe sizes of 2-8 in., the optimum thicknesses in... 

The relation between cost per unit length C of a pipeline installation and its diameter d is given by C = a + bd where a and b are independent of pipe size. Annual charges are a fraction of the capital cost. Obtain an expression for the optimum pipe diameter on a minimum cost basis for a fluid of density p and viscosity p flowing at a mass rate of G. Assume that the fluid is in turbulent flow and that the Blasius equation is applicable, that is the friction factor is proportional to the Reynolds number to the power of minus one quarter. Indicate clearly how the optimum diameter depends on flowrate and fluid properties. 

Therefore, one should select the pipe size that — after satisfying the necessaiw structural requirements — has the standard inside diameter closest to dopt. The resulting pressure gi adient will be closest to the optimum pressure gradient. But, in some cases, the actual pressure gradient could somewhat exceed the calculated optimum pressure gradient. 

Pipe designei s normally work with velocities that will not create undue vibrations, and erosion in the piping. Thus velocity limits, such as those provided in the table, are used as a further critenon for optimum pressure gradients in pipe sizing. 

L. B. McMillan, Trans. ASME, 48 1269 (1926), has presented approximate values of optimum economic insulation thickness versus the group ikb Hy with pipe size as a parameter. 

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