Process design and operations are typically concerned with the optimal selection, design, and efficient utilization of assets and resources over a time-horizon of interest. The degree of utilization of process plant components critically depends on the availability level of equipment components. These availability levels are mainly associated with equipment reliability, failure characteristics, and maintenance policies. This paper presents a system effectiveness optimization framework for multipurpose plants that involves a novel preventive maintenance model coupled with a multiperiod planning model. This provides the basis for simultaneously identifying production and maintenance policies by exploiting (i) opportunities to perform preventive maintenance during equipment idle time and (ii) flexibility in selecting different production routes to potentially mitigate the adverse effects of equipment failure on the production plan. Extensions to include design decisions are also discussed. All problems are formulated as mixed integer linear programming (MILP) models, and their applicability is demonstrated by a number of illustrative examples.