It refers to general or localized corrosion of carbon steels and other metals caused by dissolved salts, gases, organic compounds, or microbiological activity.

Corrosion is a phenomenon that occurs in most environments, so no industry can be safe from the costs of corrosion. For example, the oil, gas and petrochemical industries, factories and heavy manufacturing industries (iron smelting, steelmaking, etc.), transportation, water and wastewater, are among the industries that are severely affected by this phenomenon. This section attempts to briefly examine corrosion in several important industries.

Metals are subject to corrosion in most chemical environments, for example, metals corrode in contact with water, moisture, acids, bases, salts, oils, gaseous substances and other chemicals. In general, minerals are more corrosive than organic substances. For example, corrosion in the oil, gas and petrochemical industries is often caused by the effects of minerals such as chlorine, sulfur, etc., rather than by organic substances such as oil, petroleum and diesel.

Failure to pay attention to corrosion problems in any industrial and manufacturing unit results in hidden costs that are impossible to avoid. Economic considerations are essential in each of the corrosion control methods. Of course, there is no need to choose the most expensive corrosion control methods, because the costs incurred may not be economically justified and waste capital.

Corrosion is one of the most important problems in the cooling tower and causes cost loss and reduced efficiency of the tower. The presence of various factors in the tower makes it easy for corrosion to occur in the cooling tower. The presence of water as an electrolyte and also the presence of metals of different types in the tower as cathode and anode provides the basis for creating a chemical cell on a large scale.

Corrosion in steam boilers is caused by chemical and electrochemical reactions of metal with its surrounding environment. The most important corrosion factors in steam boilers are oxygen corrosion, carbon dioxide corrosion, corrosion due to pH drop, alkalinity corrosion, corrosion of hydrolyzable salts and corrosion of organic materials.

Corrosion in various industries, including in the oil and gas industries, imposes heavy sums of money to replace or repair equipment and machinery every year. Every year, 5% of the country's gross national product is wasted due to corrosion, and out of this 5%, about a fifth of it occurs in the oil, gas and petrochemical industries. One of the types of corrosion in oil and gas industries is corrosion caused by hydrogen sulfide gas.

Investing in corrosion control is a form of profitability. Ignoring corrosion problems in any industrial and manufacturing unit leads to hidden costs that are impossible to avoid. The first step in corrosion economics is to choose an appropriate method to minimize corrosion costs. These costs can include: production and equipment costs, loss of valuable products, undesirable product appearance, environmental costs, and so on.

The impact of various factors on corrosion damage are: 1_ Design, material selection and process 2_ Lack of necessary instructions 3_ Human error 4_ Poor inspection 5_ Poor layout, installation and coordination 6_ Failure to anticipate unwanted events 7_ Other cases