Fitness-for-service assessment

Industrial facilities and its components may suffer many types of defects throughout their service life. Since these defects can cause permanent damage, their effect on the asset integrity of the plant must be assessed. Fitness for service assessment is a special type of appraisal carried out to determine if the product or installation can fulfill its stated purposes - typically until the next shutdown - or if repair or replacement is needed in order to continue service as specified. When applying Fitness for service approach, all potential failure modes will be identified and an assessment will be conducted to ensure that the conditions for failure are not reached during the design life of the installation.

Typical failure modes considered include:

• Fracture
• Fatigue
• Gross yielding or plastic collapse
• Leakage
• Corrosion and erosion
• Stress corrosion and corrosion fatigue
• Buckling
• Creep and creep/fatigue

Typically, a Fitness-for-Service assessment results in the identification of the following:

• Equipment that contains flaws
• Equipment that does not conform to design standards and operating conditions

Once the equipment has been assessed, corrective action needs to be defined, implemented and documented.