This article presents the primary considerations and mechanisms for corrosion and explains how they are involved in the selection of materials for process equipment in refineries and petrochemical plants. It discusses the material selection criteria for a number of ferrous and nonferrous alloys used in petroleum refining and petrochemical applications. The article reviews the mechanical properties, fabricability, and corrosion resistance of refinery steels. It describes low- and high-temperature corrosion, hydrogen embrittlement, and cracking such as stress-corrosion, sulfide stress, and stress-oriented hydrogen-induced cracking. The article considers hydrogen attack, corrosion fatigue, and liquid metal embrittlement and the methods of combating them....