To transport products, pipelines have to be full, since each product propels another. There also has to be sufficient receiving capacity at the exit point to handle the batches.

A pipeline that carries a number of different products is known as a multi-product pipeline . The product batches propel one another in a predefined sequence, which is determined in line with the compatibility and specifications of the products carried (diesel and home heating oil, unleaded regular gasoline and unleaded premium gasoline). Only jet fuel cannot be transported with other products, for safety reasons.

Within a sequence, the two products in contact mix during transportation, with one of two cases arising:

a. The “contaminated” interface material, known as transmix , is compatible with one of the two products; in this case, the transmix is injected into the compatible product, generally the less “noble” one. For example, the transmix resulting from contamination of regular unleaded gasoline with premium unleaded gasoline is reclassified as regular unleaded gasoline. b. The interface material is incompatible with the other two products, in which case the transmix is channeled to dedicated storage and returned to the refinery to be reprocessed.

Case A: Downgrading of the transmix into product B.

Case B: The transmix is removed from the pipeline and stored in a dedicated tank.