Kentucky Gas line explosion

Yes and no

That is to say, not completely.  Pipeline operators all have a number of inspection and repair programs, particularly for main lines.  Distribution lines and what might be called house laterals are much more difficult to inspect.  What they are looking for is mostly corrosion damage, but they are also looking for mechanical damage -- dents and gouges.  Corrosion is largely prevented by two mechanisms: the first is with pipeline wrapping, which helps insulate (electrically and chemically) from the surrounding soil.  The second is by using an impose electrical field to prevent the chemical attack on the steel.  Neither mechanism is perfect, and they are monitored.  The pipe is also checked for wall thickness and cracks at regular intervals -- but none of the checks are really perfect, either.  Sometimes the problems which arise might be described as wear and tear, but more insidious and dangerous problems arise from damage, sometimes during construction but more often after the fact..  The damage may be physical damage to the pipe itself -- dents and scrapes -- or not as obvious, such as damage to the coatings.  The former is almost always (not always) from equipment such as a backhoe hitting the pipe; the latter may be caused by something as minor as a shovel.  Rarely -- but it does happen -- the pipe itself may be defective in the original construction -- usually a problem with a weld.



You might be interested in reading some of the reports by the NTSB (http://www.ntsb.gov/investigations/reports_pipeline.html) or the Transportation Safety Board of Canada (http://www.tsb.gc.ca/eng/rapports-reports/pipeline/index.asp) to see what some of the problems are.