Beyond Corrosion: Fitness-For-Service (FFS) Assessment (API 579)

The Corrosion Dilemma: Repair, Replace, or Keep Operating?

During a routine inspection, an area with thickness loss due to corrosion is detected in a tank or pipe. The first reaction may be to plan a costly repair or replacement. However, there is an engineering approach that allows for a more informed and cost-effective decision: the Fitness-For-Service (FFS) assessment.

What Is Fitness-For-Service (FFS) According to API 579-1/ASME FFS-1?

API 579-1/ASME FFS-1 is a standard that provides engineering assessment procedures to analyze the integrity of in-service equipment that has defects or damage, such as corrosion. In essence, an FFS analysis answers the question: "Despite this defect, is the component safe to continue operating?"

The Critical Data: How NDT Feeds FFS Analysis

An FFS analysis is not guesswork; it is based on precise data about the actual condition of the component, which is provided by Non-Destructive Testing:

• Ultrasonic Mapping (UT): Provides exact measurements of remaining thickness in the corroded area, the most important data for FFS calculation.
• Floor-Mapping (MFL): In storage tanks, MFL (Magnetic Flux Leakage) quickly scans the floor to detect and map corrosion areas.
• Acoustic Emission (AET): Can be used to monitor whether a known defect is growing under operating conditions.

Making Smart and Cost-Effective Decisions

The result of an FFS analysis can be:

1. Accept operation: Confirm that the equipment is safe to operate under current conditions.
2. Establish new limits: Allow operation under reduced pressure or for a limited time until the next inspection.
3. Recommend repair: If the analysis determines that the defect is not acceptable, a specific and scheduled repair can be planned, avoiding an emergency shutdown.

Conclusion

Offering NDT services for FFS assessments positions us as a strategic partner. We don't just find problems; we provide the quantitative data that allows our clients to manage the integrity of their assets in the safest and most economical way possible.

How we apply this in the field

At Compañía Técnica this translates into concrete work: API 653 inspections and industrial ultrasonic testing, carried out with our own equipment, deployable anywhere in Argentina, and a report signed by a technical representative registered with the Energy Secretariat. The full catalogue of audits sets out the scope of each one.

Sources and reference standards

• American Petroleum Institute (API) — publisher of the API 653, API 1104 and API 579 standards
• ASME — boiler and pressure vessel code and welding qualification