Pipelines are the veins of the world’s economy. The integrity of the systems is of utmost importance to secure availability and operational safety at a very high level. With these specially developed pigs, damages can be determined well ahead of time to prevent unplanned shut-downs. These pigs are well established tools in the day-to-day operation of pipeline systems. Which system is the most suitable one to determine the integrity of a pipeline system? How can the results be interpreted to achieve the most efficient maintenance schedule? This article will, initially, give an overview of all pig systems existing on the market. Then it will use practical examples to demonstrate how to prove the integrity of pipeline systems and what actions need to be put in place in order to regain the full operational safety of the pipeline system as quickly as possible as every downtime costs considerable amounts of money.