  This paper deals with the problem of preventive maintenance (PM) scheduling
of pipelines subject to external corrosion defects. The preventive maintenance
strategy involves an inspection step at some epoch, together with a repair
schedule. This paper proposes to determine the repair schedule as well as an
inspection time minimizing the maintenance cost. This problem is formulated as
a binary integer non-linear programming model and we approach it under a
decision support framework. We derive a polynomial-time algorithm that computes
the optimum PM schedule and suggests different PM strategies in order to assist
practitioners in making decision.
