How much life is left in your existing piping system?

Industrial piping systems over time can undergo many types of deterioration such as:

1. Corrosion under insulation (CUI)
2. Injection point corrosion
3. Service-specific and localized corrosion
4. Environmental cracking
5. Freeze damage
6. Fatigue cracking
7. Brittle fracture
8. Deadlegs
9. Erosion and corrosion
10. Creep cracking

And it can be difficult to determine the condition of an existing piping system. One of the most effective strategies is performing a fitness-for-service (FFS) evaluation.

Assessing the FFS of a piping system involves a quantitative engineering evaluation of the structural integrity of an in-service system. This evaluation helps engineers to make run-repair-replace decisions and ensure that a system will continue to operate safely.

When assessing the lifespan of a piping system, the process includes four primary parts.

Specific inspection and testing practices. Inspection types include internal and external visual, thickness measurements, vibrating piping, and supplemental strategies such as radiography and thermography.

Inspection frequency. Inspection intervals are based on the corrosion rate and remaining life calculations, the piping service classification, applicable requirements for the local jurisdiction, and the inspector’s judgement based on operating conditions, inspection history, and the current inspection results.

Evaluation and analysis of inspection data. Once the data is collected, the remaining life, corrosion rate, and the maximum permitted internal pressure for continuous operation at design temperature (MAWP) can be determined.

Repairs, alterations and re-rating. Once all the data has been evaluated, authorization and approval for repairs must be obtained. And if a change in design pressure or temperature is desired, the system must be re-rated.

While determining the lifespan of your existing piping system isn’t easy, the strategies outlined above will provide guidance in maintaining optimum performance and safe operation of this critical component.

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