Fitness for Service (FFS)

Fitness-for-Service (FFS) assessments, according to API 579-1/ASME FFS-1, are defined as the “quantitative engineering evaluations that are performed to demonstrate the structural integrity of an in-service component that may contain a flaw or damage, or that may be operating under a specific condition that might cause a failure. The typical outcome of an FFS assessment is a “go/no-go” decision on continued operation.


  • The equipment design is not fully compliant with the relevant codes.
  • The equipment experienced an impact in service, during handling or in transit.
  • The non-destructive testing and equipment inspection have noticed defects beyond the prescribed limits.
  • The equipment has never been examined, or only partly examined or inspected.


  • Avoiding to remove the equipment from service.
  • Finding a solution which is more economical than the replacement of the equipment.
  • Utilization of the equipment based on the assessment of its capabilities.


  • When NDT is available
  • Equipment integrity
  • Integrity based on future conditions
  • Pressurized equipment (reactor, heat exchangers, columns, LPG tanks)
  • Offshore piping & risers
  • Onshore piping
  • Atmospheric storage tanks which includes cryogenic (LNG)
  • The methodology can be expanded to other equipment depending upon the circumstance
  • The damage mechanisms correlate to the below non-restrictive list:
  • Stress Corrosion Cracking (SCC)
  • Metallurgical damages such as embrittlement
  • Localized corrosion
  • Fatigue (thermal or mechanical)
  • Creep
  • Crack-like flaws

Flaw Type Detection:

  • Corrosion
  • Brittle fracture
  • Fatigue
  • Crack-like flaws
  • Creep
  • Hydrogen embrittlement
  • Stress corrosion cracking
  • Dents and shell deformations
  • High-temperature hydrogen attack

Fitness for Service Application:

  • Fired heaters
  • High-energy piping
  • Turbines
  • Pipelines
  • Reformers
  • Headers
  • Pressure vessels
  • Storage tanks
  • Boiler tubes