Why maintain and inspect a pipeline?

Engineering plant follow a 'bath tub' type failure probability curve, Figure 1. This curve shows that during a structure's design life the highest failure probability is when the structure is new, or when it is old. This curve applies to automobiles, aircraft, etc., and pipeline operators will identify with it; pipelines have high failure rates early in life (e.g. hydrotest) and later in life (due to corrosion). An inspection of a pipeline will help to extend the low probability portion of Figure 1 - the goal for the pipeline operator being to extend the design life of his pipeline to 80 or even a 100 years, Figure 1.