The purpose of this recommended practice (RP) is to explain the importance of integrity operating windows (IOW's) for process safety management and to guide users in how to establish and implement an IOW program for refining and petrochemical process facilities for the express purpose of avoiding unexpected equipment degradation that could lead to loss of containment. It is not the intent of this document to provide a complete list of specific IOW's or operating variables that might need IOW's for the numerous types of hydrocarbon process units in the industry (though some generic examples are provided in the text and in Annex A); but rather to provide the user with information and guidance on the work process for development and implementation of IOW's to help strengthen the Mechanical Integrity (MI) program for each process unit.