When are FFS assessments used?
Fitness-for-service assessments evaluate the structural integrity of components and their suitability for continuous service. Procedures such as BS 7910:2013, API 579/ASME FFS-1, ASME B31G, DNV-OS-F101 and FITNET enable the integrity of critical pressure components and welded structures to be assessed against different failure modes, using a validated engineering approach.
An FFS assessment provides a quantitative measure of the structural integrity of a component containing flaws. Standards used to carry out these assessments provide guidelines which can be used to make run-repair-replace decisions, assisting plant management in identifying appropriate mitigation actions to ensure that the component can be operated safely.
The method can be used to support design, fabrication, operation, change of service and life extension programmes, and is employed widely in a range of industries, including power generation, oil and gas, chemical processing and aerospace. Assessments of this type are widely used as part of the plant lifetime management process, to confidently increase availability, reliability, efficiency and safety.
Any unplanned shutdown of a manufacturing or process plant is expensive in terms of both loss of production and the manpower required to solve a particular mechanical integrity issue. Fitness-for-service assessments, especially at the lower ‘screening assessment’ levels, can quickly determine if equipment is safe for immediate return to service. Higher levels of assessment can be complex and time-consuming but still generally require less time than the ordering, supply and commissioning of replacement equipment.
Through established multidisciplinary teams, with specialist knowledge in areas of fracture mechanics, fatigue, finite element analysis, materials, inspection and welding, TWI is able to provide industry-leading services to our international network of Industrial Member companies. We have carried out FFS assessments on pressure vessels, slug catchers, storage tanks, pipelines, piping system and high-temperature equipment in accordance with industry-accepted standards.