A full Reliability, Availability and Maintenance (RAM) model was built from the conceptual design, incorporating process equipment, economic and performance data to quantify the availability of the proposed design. Using the redundancy optimization module within RAM-int, the design configuration was optimized on the basis of equipment redundancy and plant configuration. The RAM model included the costs of the equipment, costs of the maintenance, failure modes, start up shut downs, manning levels, time slices over the life of the asset to reach the optimum design to minimize the LC or TCO.
Key to the optimization model is the ability to model the costs of maintenance. A simple example is one pump is cheaper to maintain than two pumps, but two pumps increase availability and improve reliability, but increase the Capex of a project, but it also depends on how the second pump is maintained as this will directly effect the reliability of the system.