Next to fuels for transport, petrochemical feedstocks for manufacturing the raw material for plastics must rank as the most important products from the refining process, both in terms of the huge range of products made from plastics and the value added.

Increasingly, refineries are closely integrated with adjacent petrochemical plants - for example Fawley, Grangemouth, Stanlow and Teeside - or export these feedstocks to chemicals production plants within the UK or overseas.

Feedstocks for chemicals are derived from processing gases from a cracker or other upgrading unit. The principal feedstocks are ethane, butene, benzene and propene which are made into ethylene, butylene and propylene.

These base chemicals are the building blocks for a whole range of polymers manufactured in a polymerisation plant. The raw material is often produced in the form of pellets which can then be subjected to a number of processes involving heat combined with extrusion, pressure moulding or blow moulding depending upon the product.

Some of the end-uses are illustrated below.