Managing an IOW Implementation Program from Development to Sustainment

Introduction

Since the publication of API RP 584, “Integrity Operating Windows,” there have been increasing requests for integrity operating window (IOW) assessments in the industry [1, 2]. However, in that time, we have observed that:

• The intent of IOWs is not fully understood by some Sites / Organizations.
• IOWs are often defined, but a full management program is not often implemented.
• When implemented, they are not sustained as part of the integrity management program.

The objective of this article is to provide a road map that will help owner-users more cost-effectively implement and sustain an IOW program tailored to their operation.

What Is an IOW?

An IOW defines the maximum or minimum operating process variables that should be maintained to meet the intended design life of pressure equipment. This is illustrated in Figure 1.

Figure 1 can be broken down as follows:

• The green area represents the estimated norm and the operating conditions for assets to achieve optimal design life.
• The yellow area represents conditions that could compromise the design life but do not pose an immediate safety risk. Operation in this area may not require immediate response but often requires close monitoring and involvement of the integrity management team.
• The orange area represents the safe operating limit (SOL) boundary. Operation in this area requires immediate action to return the equipment to normal operating conditions, and an engineering assessment should be required to determine the fitness-for-service of the asset.