Fitness For Service (FFS)

Last update: Jan 13, 2017

Fitness for Service (FFS) is a best practice and standard used by the oil & gas and chemical process industries for in-service equipment to determine its fitness for continued service. FFS serves as a rational basis for defining flaw acceptance limits and allows engineers to distinguish between acceptable and unacceptable flaws and damage based on industry recognized and generally accepted good engineering practices (RAGAGEP).

The FFS of any particular material is determined by performing a fitness-for-service assessment per standardized methods and criteria. Performing accurate FFS evaluations is an integral aspect of fixed equipment asset integrity management as an alternative to using the original construction design code. The FFS of a piece of equipment may be viewed both in terms of current and future FFS or remaining life.

Most equipment can continue in service despite small flaws, and to repair or replace equipment that can still be used would be an unnecessary and costly expense. In addition, unnecessary weld repairs can do more harm than good and create unnecessary risks to personnel in many cases.

API RP 579-1/ASME FFS-1, Fitness for Service, Second Edition, is one example of a FFS methodology currently used by industry professionals. In general, most FFS assessment standards are broken into multiple levels. Each successive level (e.g., Levels 1, 2 and 3 of the referenced API 579-1/ASSME FFS-1 standard) requires increasing amounts of data, calculations, effort, and cost to arrive at the most accurate outcomes and possible longer equipment remnant life. In addition to calculations, FFS involves the consideration of additional data (e.g. pitting patterns and depths, corrosion morphology or shape and depth, crack depths and lengths, operating conditions, materials properties, etc.). Inspection information is often critical input to a FFS assessment.

 

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March/April 2014 Inspectioneering Journal
By Guy St-Arneault, P.E. at GCM Consultants, and Hugo Julien, P.E. at GCM Consultants

Since important decisions will be based on the results of the fitness-for-service (FFS) determination, you need to be sure that you have a strong FFS team. But what are the key ingredients of a good FFS team? This article provides some guidelines to help you answer this question.

Managing Fired Furnace Tubes in Refineries
January/February 2014 Inspectioneering Journal
By Antonio Seijas at Phillips 66 Company

Fired furnaces in the petrochemical and refining industry are critical pieces of equipment that can have a major impact on process unit safety, reliability, and economics. They are complex pieces of equipment, where tubes and other pressure boundary components might fail due to relatively short periods of upset conditions.

When Bad Things Happen to Good Pressure Vessels: A Story of Localized Metal Loss
November/December 2013 Inspectioneering Journal
By Michael Turnquist at Quest Integrity Group

While there are many types of damage mechanisms that can occur in a piece of equipment, localized metal loss is one of the most common. If an inspection reveals that metal loss has occurred, many questions are raised...

Fitness for service: a powerful tool to keep your plant running safely
Partner Content

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.

Auto-Refrigeration / Brittle Fracture Prevention And Process Safety Mitigation
November/December 2013 Inspectioneering Journal
By Ralph E. King P.E. at Stress Engineering Services, Inc.

Auto-refrigeration is a process where an unintentional and/or uncontrolled phase change of a hydrocarbon from a liquid state to a vapor occurs, resulting in a very rapid chilling (refrigeration) of the liquid containing local equipment and/or piping. This phenomenon can result in a catastrophic ‘break-before-leak’ scenario commonly referred to as brittle fracture.

FFS using 3D Structured Light and Pipeline Integrity
September/October 2013 Inspectioneering Journal
By Joe Pikas at Technical Toolboxes

Even though oil and gas pipelines and their related facilities are generally safer for people and the environment compared to other means of transportation, occasional leaks and failures due to corrosion and other defects have become an issue in maintaining pipeline integrity.

Blog
September 9, 2013 By Greg Alvarado at Inspectioneering Journal

We’ve been discussing Scalable Accuracy and its use related to Lifecycle Management technologies available to owner/operators. The last few topics have included Risk Based Inspection, Fitness for Service using Accuracy, the approach for Equipment Lifecycle Management and, to lay the foundation for proper thinking, making the case for Scalable Accuracy.

Blog
August 26, 2013 By Greg Alvarado at Inspectioneering Journal

This blog post continues our discussion from the previous posts on scalable accuracy. We started with a post outlining the steps prior to using scalable accuracy. Then we walked through the scalable accuracy approach to Fixed Equipment LCM. While I normally start with RBI when discussing scalable accuracy, it will be easier to use an example of Fitness for Service as our starting point.

Have you determined whether or not your equipment is subject to Brittle Fracture?
Partner Content

Auto-refrigeration can impose low temperatures onto process vessels and piping causing them to be at risk of brittle fracture, the sudden break-before leak phenomena that can result in catastrophic rupture of the equipment.

Blog
August 19, 2013 By Greg Alvarado at Inspectioneering Journal

Continuing from last week’s blog, I want to go in depth into scalable accuracy for fixed equipment lifecycle management. In this post, I want to outline the scalable accuracy approach to fixed equipment lifecycle management.

Blog
August 12, 2013 By Greg Alvarado at Inspectioneering Journal

In the next few blog posts, we will be going in depth on scalable accuracy. This post walks through the thinking needed prior to initiating. Then we will discuss two technologies immediately available to plant operators for fixed equipment life-cycle maintenance: Risk Based Inspection (RBI) and Fitness for Service (FFS).

The Challenge of Inspection and Assessment of Critical Piping Systems in Chemical Plants
July/August 2013 Inspectioneering Journal
By James Widrig at Quest Integrity Group

Inspection and fitness-for-service assessments of critical in-plant piping systems are a concern for the chemical industry. This presents a potentially insurmountable task and discovery of a number of areas where the condition is at risk.

Understanding Key Performance Indicators (Lest We Forget...) Part 2
Blog
April 29, 2013 By Greg Alvarado at Inspectioneering Journal

This is my second of three posts on Key Performance Indicators (KPIs) based on requests and discussions on the issue.  In part 1 of this series I provided a brief overview of KPIs and their ability to predict good, poor, and sometimes dangerous performance in our quests to achieve certain objectives and goals.

Blog
March 3, 2013 By Greg Alvarado at Inspectioneering Journal

This is a question with which I frequently like to start the API RBI 580/581 training course when I am instructing. It is meant to provoke the attendees to really think hard about why they order an inspection or really think about inspection strategies.

Fitness-for-Service Assessment: Severe Local Corrosion
March/April 2013 Inspectioneering Journal
By Greg Garic at Stress Engineering Services, Inc.

If an operator finds cracking in a furnace waste heat boiler, excessive thinning in an absorption tower, or severe bulging in a converter, FFS assessments—not standard code analyses—are needed to evaluate the unit’s mechanical integrity. 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.”

Real-time Operating Decisions Made Easier
January/February 2013 Inspectioneering Journal
By Devon Brendecke, P.E. at Quest Integrity Group

The benefits of adding fitness-for-service (FFS) assessments to energy sector reliability projects are numerous. The acceptance of API 579/ASME FFS-1 is increasing across the energy sector and other industries, as these benefits have been demonstrated in a wide range of projects. Several of these benefits are illustrated in this article using real-world examples.

Evaluating Fitness for Service of Damaged Equipment
September/October 2012 Inspectioneering Journal
By Peter Carter, PhD, PE at Stress Engineering, Inc., Joe Frey, PE at Stress Engineering, Inc., and Mike Guillot, PhD, PE at Stress Engineering, Inc.

An all too familiar scenario in power plants is one in which an inspection finding occurs late in an outage and consequently, the return to service date may need to be postponed to allow time for corrective action. Historically, cracks or thinned spots were typically repaired without question.