Fitness for Service (FFS) per API 579-1/ASME FFS-1

Overview

TCR undertakes Fitness For Service (FFS) Assessment based on Level 2 and 3 of BS 7910 standards and API 579. Our fracture mechanics methodology and its application have been successfully proven worldwide across industries, including nuclear pressure vessels to high consequence items in the exploration, refining, petrochemical and construction industry.

A process, plant, and equipment are often exposed to corrosive environments and/or elevated temperatures. Under these conditions, the material used in the equipment can degrade or age with time. Important equipment such as pressure vessels, piping, and storage tanks become older, the plant operator must decide if they can continue to operate safely and reliably to avoid injuries to personnel and public, environmental damage, and unexpected shutdowns. Fitness for service assessment procedures provide a means for helping the plant operator make these decisions on established engineering principles.

Fitness for service assessment is a multidisciplinary engineering analysis that ensures all process and plant equipment such as pressure vessels, piping, and tanks operate safely and reliably for the desired period of operation and until the next turnaround or planned shutdown occurs in the future. API Recommended Practice 579 provides a general procedure for assessing fitness for service. This assessment procedure evaluates the remaining strength of the equipment in its current state, which may have degraded from its original condition. Common degradation mechanisms include corrosion, localised corrosion, pitting and crevice corrosion, hydrogen attack, embrittlement, fatigue, high-temperature creep and mechanical distortion. Methods for evaluating the strength and remaining service life of equipment containing these types of degradation are presented and reviewed

Common Reasons for Assessing The Fitness for Service of Equipment Include:

• Discovery Of A Flaw Such As A Locally Thin Area (LTA) or Crack
• Failure to Meet Current Design Standards
• Plans for Operating Under More Severe Conditions than Originally Expected

Outcome of Fitness for Service Assessment

• Decision to Run, Alter, Repair, Monitor, or Replace the Equipment
• Guidance on Inspection Interval for the Equipment

Fitness for Service Assessment uses Analytical Methods to Evaluate Flaws, Damage and Material Aging Based On:

• Stress Analysis may be performed using Standard Handbook or Design Code Formulas or by means of Finite Element Analysis (FEA). With modern computer technology, the use of FEA is quite common.
• Fitness for Service Assessment requires both, knowledge of past operating conditions and a forecast of future operating conditions. Interaction with operations personnel is required to obtain this data
• Non-Destructive Examination (NDE): NDE is used to locate, size and characterise flaws
• Material Properties: The material properties include information on material damage mechanisms and behaviour in the service environment, especially on the effects of corrosion and temperature

The 8-Step Workflow Per Part

• 01 Flaw and damage-mechanism identification.
• 02 Applicability and limitations of the procedure.
• 03 Data requirements (design, operating, inspection, materials).
• 04 Assessment techniques and acceptance criteria.
• 05 Remaining life evaluation.
• 06 Remediation.
• 07 In-service monitoring.
• 08 Documentation.

Anchor Case Study 1: HMEL Bathinda Isomerization Reactor 503-R-001

March 2012 temperature excursion: peak 710 degrees Celsius for 1 minute, 44 minutes above 700 degrees Celsius. Full damage-mechanism workup including HTHA per Nelson curve API 941. In-situ replication at 60 locations. Hardness mapping. TOFD. Automated Ultrasonic Backscatter Technique (AUBT). Plus a laboratory simulation experiment with welded coupons. Certified fit-for-service.

Monitored through 2019 with no CS3 crack growth, no shutdown, no replacement.

Fitness-for-service on video

TCR publishes its own work on YouTube. One film is below, recorded on the bench and in the field. Each one loads only when you press play: nothing is requested from Google before that.

• Podcase Episode 2 : Integrity Despite Deffects- Fitness For Service