THE PETROLEUM INDUSTRY is usually divided into oil and gas production, refining, and oil and gas products. These encompass a wide variety of corrosive environments that must be considered during the process of materials selection and corrosion control management. The corrosive environments include acid gases, such as carbon dioxide (CO2) and hydrogen sulfide (H2S), and salt water. Refinery operations involve complex chemical systems and many corrosive environments. Management of these systems involves a wide range of activities by the producing, refining, and service companies.