API 579 Assessments

Fitness-For-Service (FFS) assessments, according to the American Petroleum Institute (API), are “quantitative engineering evaluations that are performed to demonstrate the structural integrity of an in-service component containing a flaw or damage.”

Publication of API RP-579 was a boon to the petroleum refining industry.  It provided clear guidelines for dealing with degraded equipment in a manner that often allowed continued service without requiring repair, replacement, or reduction of the pressure rating.

FFS assessment techniques are applicable to a wide range of damage types: LTA’s, cracks, creep damage, dents, and more. These are very powerful analytical tools that often allow operators to not only keep the plant running, but to keep it running safely. It should be noted that the information presented in this discussion is only a brief introduction to FFS assessment. Before applying any of these techniques, it is essential that engineers be thoroughly familiar with API RP-579 and its implementation.

Our FFS engineers are highly experienced in the proper application of these advanced techniques. They are committed to providing reliable solutions that are not only financially feasible and structurally sound, but help improve safety, reliability, and profitability. Serving the oil refining, petro-chemical, chemical, power generation, and pipeline industries, Our FFS experts combine unmatched experience and the most effective engineering tools to solve problems in a number of plant components including FCCU’s, coke drums, pressure vessels, reactors, heaters, boilers, power generation equipment, piping, pipelines, turbines, and structures.

Example Equipment Types:

  • FCCU's
  • Coke Drums 
  • Pressure Vessels
  • Reactors
  • Heaters
  • Boilers
  • Power Generation Equipment and Piping
  • Process Piping
  • Pipeline
  • Turbines

Example Damage Mechanisms and Types:

  • Brittle fracture
  • Corrosion, erosion, or erosion-corrosion under various thinning modes: general, local, and pitting
  • Laminations
  • Hydrogen Blisters,  HIC and SOHIC damage
  • Bulges and out-of-roundness distortion
  • Crack-like flaws, including creep, stress corrosion, fatigue, and corrosion-fatigue crack growth
  • Dents, gouges and dent-gouge combinations
  • Evaluation of hot spots
  • Heater tube remaining life
  • Evaluation of high temperature equipment for creep and creep-fatigue damage
  • Fire damage
  • High Temperature Hydrogen Attack (HTHA)
  • Thermal and mechanical fatigue
  • Ring joint flange cracking
  • Tank shell and edge settlement
  • Local PWHT of weld repairs
  • Modeling of weld residual stresses and incorporation into crack-like flaw assessments
  • Wind-induced vibration of towers, stacks and pipelines
  • Mechanical vibration
  • Blast loading and other dynamic effects
  • Hot tap thermal analysis