The objective of this study is to develop a corrosion model that would help analyze the reliability of an offshore pipeline with corrosion defects. Petri net is used to develop the corrosion model because petri net is able to handle the stochastic nature of the pipeline corrosion. It is also capable tp capture the degraded states of the pipeline. Two corrosion models is presented for comparison, with repair and no repair on the pipeline. The developed model then validated with Monte Carlo simulation with graphical approach.