Pipeline contamination is usually understood to mean both the mixing effect produced when two different products transported by the same pipeline come into contact with each other and often the product of such mixing, as well. This product is often referred to as “contamination” or as “interface”. Clearly such intermixing is generally less serious in crude carrying, pipelines where each batch can become somewhat polluted by the batches immediately preceding and immediately following without significant damage. However, the situation is different in a finished products pipeline, which may carry products as different as aircraft gasoline and light fuel oils. This article presents a brief description of the main factors influencing contamination with the objective of optimize conditions operating and to drive the more important respects about them.