API RP 584-ed.2

Annotation of standard text API RP 584-ed.2 :

API RP 584, 2nd Edition, December 2021 - Integrity Operating Windows

Purpose and Scope

The purpose of this recommended practice (RP) is to explain the importance of IOWs for process safety management and to guide users in how to establish and implement an IOW program for process facilities. Its express purpose is to minimize 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 IOWs or operating variables that might need IOWs for the numerous types of process units in the industry (though some examples are provided in the text and a list of process variables for some example process units in included in Annex A); but rather to provide the user with information and guidance on the work process for development and implementation of IOWs to help strengthen the Mechanical Integrity (MI) program for each process unit.

The key goals of an IOW program are:

1) Defining IOW limits which will result in predictable and acceptable levels of equipment degradation to meet reliability expectations.

2) Enabling effective communication of equipment limits and exceedances between key Process, Operations, Maintenance, and other MI stakeholders to facilitate safe and reliable process operation and management.

3) Facilitating the reliable operation of equipment without loss of containment or the need for unplanned maintenance activities between scheduled outage or shutdowns.

The scope of this standard includes:

— definitions of IOWs and related terminology;

— creating and establishing IOWs;

— data and information typically needed to establish IOWs;

— descriptions of the various types and levels of IOWs needed for process parameters;

— risk ranking IOWs;

— documenting and implementing IOWs;

— monitoring and measuring process variables within established IOWs;

— communication of IOW exceedances;

— reviewing, changing, and updating IOWs;

— integrating IOWs with other risk management practices;

— roles and responsibilities in the IOW work process; and

— knowledge transfer to affected personnel.

This RP outlines the key elements in defining, monitoring, and maintaining IOWs as a vital component of integrity management (materials degradation control) and assisting in the inspection planning process, including Risk-Based Inspection (RBI). Other Process Safety systems may be affected by or involved with the IOW program, including management of change (MOC), process safety information (PSI), and training. For purposes of this RP, these systems are only addressed to the extent of mentioning the integration aspects that are needed with the IOW program.

This RP does not cover operating windows established for normal process control, such as for the purpose of maintaining product quality. It also does not cover operating windows for other PSM issues, including avoidance of operating error, that do not relate to control for the purpose of maintaining equipment integrity and reliability. However, IOWs should be integrated into a common system for managing all operating variables and limits.

Examples of equipment types, damage mechanisms and operating conditions that are typically not addressed by IOWs:

— Design limits for vessels and piping (i.e. design pressure and temperature limits).

— Rotating equipment, instrumentation, and electrical hardware. IOWs established within the scope of this RP typically cover only fixed equipment but can be extended to other types of equipment at the option of the site. Product quality or product specification limits.

— Some damage mechanisms that can occur or are strongly influenced by unanticipated short-duration upsets are not typically controlled by IOW limits. They are controlled by proper materials selection, design, by operations or maintenance procedures, or both. Examples include:

— Brittle fractures that may occur during hydrotest,

— Stress corrosion cracking (SCC) of sensitized stainless steels at downtimes controlled by soda ash treatment,

— Chloride SCC at low point drains in stainless steel equipment during unit start-ups controlled by pre-startup draining and drying of stainless systems.