API 579 Fitness-For-Service (FFS) Evaluations

Why Use API 579 Fitness-For-Service Evaluations?

Fitness-For-Service (FFS) evaluations determine whether equipment can continue operating safely after damage is discovered. Instead of automatically repairing or replacing equipment, an engineering assessment evaluates the actual severity of the damage and establishes a safe operating envelope.

FFS assessments are commonly applied to pressure vessels, storage tanks, and piping systems when deterioration or abnormal conditions are identified during inspection.

Damage mechanisms that can be evaluated include:

• Localized and general metal loss

• Hydrogen blistering and hydrogen damage

• Shell distortion and bulging

• Crack-like flaws

• Fire damage

• Dents and mechanical damage

• Laminations and fabrication defects

An API 579 evaluation determines whether equipment must be repaired immediately, monitored for continued service, or can safely remain in operation — often preventing unnecessary shutdowns and costly replacement.

What FFS Evaluations Provide

• Confirmation of safe continued operation under defined conditions

• Identification of required repairs versus acceptable operation as-is

• Remaining life determination

• Documented engineering justification for operation or corrective action

• Support for risk-based inspection and mechanical integrity programs

By basing decisions on engineering analysis rather than assumption, facilities can avoid unnecessary expense while maintaining safety and compliance.

Our API 579 Evaluation Services Include

• Integration of inspection findings and Non-Destructive Examination (NDE) data

• Level 1 and Level 2 assessment calculations with documented results

• Level 3 advanced analysis when required, including finite element modeling

• Remaining life and monitoring recommendations

• Repair recommendations when necessary

• Clear documentation defining the appropriate path forward

Supporting Safe Operation

Equipment failures can lead to injury, environmental incidents, and significant property damage. Fitness-For-Service assessments provide a defensible engineering basis for operating decisions, helping prevent failures while minimizing unnecessary repairs or downtime.