Integration of Integrity Operating Windows into Process Safety Management

Integrity Operating Windows (IOWs) are an important component of a world-class mechanical integrity program. IOWs are not a new concept. They have been around in different forms for many years. However, due to some recent high-profile industry indictments and with the publication of the first edition of API RP 584 Integrity Operating Windows (2014) and the release of the second edition (2020), increased focus has been placed on these concepts within the refining and petrochemical industry. The more recent first edition of API RP 970 Corrosion Control Documents (2018) also discusses the importance of IOW programs as part of a complete Corrosion Management System. Many owner-user organizations that do not currently have an IOW program in place are considering implementing them.

IOWs are defined as established limits for process parameters that affect the integrity of fixed equipment and piping. When operating parameters deviate from these limits, degradation is more likely to occur. IOWs should be considered a subset of a larger group of unit operating parameters. If operations are kept within these limits, degradation should be predictable; however, this does not necessarily mean low rates of damage.

API 584 defines IOWs in three categories:^[1]

• Critical – Parameters where rapid deterioration occurs when the limit is exceeded (typically hours to days).
• Standard – Parameters where exceedances over a specified period of time will cause increased degradation (typically weeks to months or within a turnaround interval).
• Informational – Parameters monitored for long-term damage mechanisms.

Implementing a new IOW program can have many challenges, which can be mitigated through attention to detail in the planning and implementation stages of the program to ensure that it will remain evergreen. The list below provides best practices that owner-users have followed when planning and implementing an IOW program.