This article presents a simple way to increase security in PIG launchers and receivers operation using mechanical interlock devices for manually operated valves in the operations of sequential processes to ensure that work procedures are followed by operators. So, these devices with their coded keys can ensure the operational safety of persons and installation, because they will obligate the people following the complete and correct procedure to use PIG launcher and receivers. To prove that it is possible to do this, will show some examples of applications that can be easily found in the oil and gas, pipelines and systems such as PIG launchers and receivers, by-pass systems, and another’s.