This paper proposes a decomposition approach combining heuristic algorithms and Mixed Integer Linear Programming (MILP) models to solve the long-term scheduling of a multiproduct pipeline connecting a single-source to multiple distribution centers. The solution considers many operational aspects, such as simultaneous deliveries, pipeline maintenance periods, deliveries of multiple products during the same pumping run, and rigorous inventory control. A long-term scheduling problem from the literature was solved to validate the proposed approach. This problem is composed of a straight pipeline connecting a refinery to 3 distribution centers and transporting 4 different oil derivatives. The approach was able to obtain an operational solution in less than half a minute of CPU time. Moreover, additional tests using the same scenario were executed in order to analyze the performance of the developed decomposition approach.