Pipelines: What is the difference between critical and non-critical interfaces?: Introduction
A critical interface is the point in the pipeline where two products with incompatible specifications meet, for example petrol and diesel. If the resulting mixture were added to either the product ahead or behind it in the pipeline, it would make either ‘off-specification’ - contaminating them so they could not be used as originally intended.
A non-critical interface is the point in the pipeline where two products with compatible specifications meet, for example, diesel and kerosene, which could be used as a product, such as off-road fuel or for heating.