A sound knowledge of corrosion problems in the petrochemical industry is necessary for the development of efficient, practicable methods of corrosion control and the selection of corrosion-resistant alloys (CRAs) that will reduce the expense of maintaining equipment and facilities.

The production of petrochemicals involves the handling, treatment and processing of hydrocarbons and organic chemicals which are non-corrosive or weakly corrosive towards steel and alloy steel. However, contaminants in hydrocarbons – strong mineral acids (sulphuric, hydrochloric, phosphoric and nitric) and strong and weak bases (soda ash, caustic soda and ammonia) – require the use of corrosion-resistant stainless steels.

Petrochemicals are chemicals produced in whole or in part from petroleum or natural gas. The products range in the ultimate forms, through plastics, synthetic fibbers and rubbers, industrial solvents, detergents, components of paints, fertilisers, glues, insecticides, agrochemicals, etc.

From the outset, the petrochemical industry devoted a great deal of effort and development for improving its processes, technologies and intermediate and final products. The industry established computerised information services including databases and expert systems; research laboratories based on modern techniques; pilot plants for processes, equipment and plants.

The prediction, prevention and diagnosis of corrosion and the solution of problems related to it are central topics in research and development activities.

Since the 1980s, increased competition worldwide has driven many petrochemicals companies to review their operations in order to maintain and increase efficiency and productivity. Now the focus is on achieving high quality to preserve their share of the market.

In recent years, petrochemical plant managers and operators have shown a strong concern for the quality of the environment and the health of their workers as well as the population in the vicinity of plants and facilities. To control pollution in petrochemical plants, several operations are required, e.g. waste water treatment, waste gas treatment and dust emission control.

Frequently, petroleum refineries are fully integrated with petrochemical plants, using common utilities e.g. cooling water towers, vapour and energy generation, control and research laboratories, maintenance, quality assurance, risk assessment and safety services.

A typical, large petrochemical industry exists in Mexico; a vast country blessed with rich resources of natural gas and petroleum, providing raw materials for an extensive petrochemical industry, directed by PEMEX – Petroleos Mexicanos, a state-owned oil and gas company. It produces many petrochemicals (table 1) in three large petrochemical complexes: Morelos, Pajaritos and Cangrejera, situated near the river, port and town of Coatzacoalcos on the Gulf of Mexico. PEMEX Petroquímica produces about 60 different petrochemical products, which are classified into basic and secondary petrochemicals. The petrochemical complex at Morelos is the most modern; it manufactures raw materials for synthetic fibres, plasticizers, resins, elastomers and solvents. It operates nine processing plants: ethylene and propylene and their derivatives, mainly polyethylene and polypropylene, and auxiliary facilities such as power plants, water treatment, steam generation, laboratories, workshops, transportation services, etc.

The petrochemical plants implement ISO Standard 9002, to assure quality of operation and production, after receiving certification following audit by an authorised company. The quality of the environment is maintained using guidelines set up by Mexico’s Environmental Protection Office, sedesol.

Several fertiliser companies operate plants in the industrial park of Coatzacoalcos, e.g. Albright and Wilson Troy Industries, producing various grades of phosphoric acid, sulphuric acid, TSPP and phosphatic fertilisers; Agro Nitrogenados (AgroMex) manufactures ammonia, nitric acid, urea ammonium nitrate, nitrogen fertilisers. In addition to ISO 9002 they are implementing the ISO Standard 14001 for the preservation and protection of the environment. Austenitic stainless steel is the principal, critical material for fabrication of production, storage and transportation equipment in those plants.