“Fit for Purpose” Design of a Desalinated Seawater Pipeline

This paper summarizes various trade-off studies carried out during the pre-feasibility phase of a desalinated seawater pipeline system intended to minimize the capital expenditure (CAPEX), achieve a reasonable operation expenditure (OPEX) and comply with the “fit for purpose” concept required by the owner. The trade-off studies and analyses carried out include: pipeline route optimization; economical diameter selection and telescoping pipe wall thicknesses; optimum number of pump stations; selection of internal liner; and whether a closed or an open system is being designed, among others. The value of this work is to show that completing the minimum necessary assessments, regardless of assumptions or opinions, unless it is something evident, is fundamental to support a robust and economical design. Furthermore, completing these studies was not exceedingly expensive as some people may have thought. In fact, time period in which the flow assurance work was developed for the different trade-off studies described in this paper was approximately 3-4 months. Finally, the work was reviewed by an independent consultant firm contracted by the owner. The results of this assessment are discussed too.