Make Informed Run, Repair, or Replace Decisions

Deteriorating assets, including fixed equipment, structures, foundations, and other infrastructure, cost businesses billions of dollars per year. Assessing the integrity of your in-service equipment will help you proactively solve issues, minimize failures, and save money.

Fitness-for-service (FFS) is focused on plant safety, improving operational performance, and avoiding unnecessary repairs or replacements. E2G conducts FFS assessments to help you increase operational reliability and extend equipment life by making informed run, repair, or replace decisions on your in-service equipment.

Learn More About Fitness-for-Service From E2G's Experts

What is Fitness-for-Service

FFS assessments are conducted on in-service equipment to assess the structural integrity of pressure vessels, piping, and tanks to determine whether the component is fit for continued operation or if the flaw or damage will cause a failure. Implementing FFS into an asset’s lifecycle management program will improve safety, reduce risk, optimize construction, maximize equipment availability, and reduce future maintenance and inspection costs.

Proactive vs. Reactive FFS

FFS assessments are applicable throughout an asset’s lifecycle. E2G recommends conducting proactive FFS assessments to support your facility’s asset integrity management program.

Proactive FFS

When? Proactively review the results of detailed remaining life evaluations, rigorous engineering evaluations, and damage mechanism reviews.


  • Extend equipment life and optimize inspection intervals and inspection tasks  
  • Understand the effects and potential for future damage progression  
  • Establish screening tools to aid in non-destructive examination (NDE) and flaw sizing exercises

Reactive FFS

When? Conduct FFS assessments when flaws or damage are discovered during equipment shutdown inspections or on-stream inspections. 


  • Make informed run, repair, or replace decisions on in-service equipment 

E2G's FFS Assessment Workflow

Our mechanical and structural engineering team combines the appropriate level of technology with their extensive industry experience to provide practical and cost-sensitive recommendations to challenging FFS problems. Our team offers many related services to help improve the reliability of and extend equipment life, from both a reactive and proactive approach, including:

The flexible design and large size can cause shell distortion. Plus, foundation settlement, operational upsets, high wind or seismic events, and inadequate repair techniques can lead to damage. Regular inspections only identify localized and widespread shell distortion. E2G applies Level 3 FFS assessments to ASTs to determine if the tank can continue service in the damaged condition.

SagePlus software allows you to conduct Level 1, Level 2, and Level 3 FFS analysis using its large set of analysis modules that incorporate the latest API 579 codes. You will achieve safer facilities and plants by evaluating equipment design and in-service conditions to make informed engineering decisions on the life of fixed equipment, piping, and structures. Many users prefer eecWebTools for Level 1 and Level 2 FFS calculations and use SagePlus for in-depth Level 3 calculations.

SIMFLEX-IV, a cloud-based pipe stress analysis software, helps you proactively evaluate dynamic and static piping stresses to maintain integrity and code compliance across your entire piping system. Use the once-through workflow to create piping stress models, visualize geometry and support locations, analyze the effects of both dynamic and static stresses, and compare results to ASME piping code requirements.

E2G's Role in Advancing FFS Methodologies

Our engineers pioneered the advancement of FFS technologies and were the lead investigators of the international standard API 579-1/ASME FFS-1, Fitness-for-Service. Today, the document is the FFS standard of choice for other industries such as pulp & paper, biofuels, food processing, and non-commercial nuclear. E2G was the lead investigator of API 571, Damage Mechanisms Affecting Fixed Equipment in the Refining and Petrochemical Industry. Understanding the effects of and potential for future damage progression is critical in completing an effective FFS evaluation.

Recommended Reading

Fitness-for-Service Expertise

Our mechanical and structural engineering team has completed thousands of FFS assessments for pressure vessels, piping systems, and storage tanks. As pioneers of FFS technologies and lead investigators on many international standards, our team combines their extensive experience with state-of-the-art technology to help extend the lifecycle of your existing assets and create safe operating environments.

Our experts:

  • Have 200+ years of combined field experience
  • Pioneered development of FFS
  • Are the primary authors on WRC 528 and WRC 562
  • Serve as lead investigators on API 579 and API 571
  • Provide emergency onsite support within 24-hours
  • Are the committee leader for the- API 579 Part 3 brittle fracture screening task group