There are two areas of concern in a well designed Pipe Line. One is internal and the second one is external. For external maintenance, again there are two types, one is sub-surface and surface Piping. The internal damage control remains a common issue for both sub-surface and surface Piping which are normally met depending on the Product flow and its corrosive effect.
The usual method of chemical injections to neutralize the corrosive effect has to be seriously looked in to. For External side of sub-surface Piping, Good wrapping technique and selective soil filling with clear sign posts is a good practice for long lasting effect.
For external side surface piping, a regular interval painting practice after inspection /grit blasting. . In all cases condition monitoring at regular intervals using intelligent PIG , detection tests and un interrupted cathodic protection will improve the life span of Pipe line.