Great care is taken in developing an initial basis of design prior to the start of a FEED or detailed design. Unfortunately this normally results in a set of design throughput rates, pressures and temperatures which may not take into account the practical aspects these parameters may have on equipment selection and sizing. In addition, history has shown that as more information is obtained about the target reservoirs the anticipated demands on the production facility tend to change during the design, during the construction and even after the facility is installed.
Optimizing facility design for the specific parameters in the basis of design is often counterproductive. Facilities engineers need to understand the rationale behind the basis of design and question the assumptions in light of practical choices of equipment selection and system design. To do this properly, the facilities engineer must use judgment in selecting equipment by understanding the accuracy of the data used to develop the BOD as well as understanding the effects on equipment performance of changes in flow parameters.