De-emphasize Capital Costs For Pipe Size Selection

Piping represents a major cost for projects in the chemical process industries (CPI). Larger pipe diameters increase upfront capital costs for a project, but the lower pressure drops afforded by large pipes mean less power is required to move the fluid through the pipe. Optimizing pipe diameter becomes an exercise in balancing the capital cost savings realized by using smaller pipes with the power required to pump the fluids. Figure 1. Selected pipe diameter is never below Dopt. The liquid flowrate here is 28 lb/s 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. In this analysis, the authors evaluated the sensitivity of optimal pipe diameter to changing capital costs, and concluded that variable capital costs have only a minimal effect on commercial pipe size selection up to diameters of 10-in. nominal pipe size (NPS). Once…