Non-destructive testing (NDT) is an interdisciplinary field that includes non-invasive inspection of processing and storage equipment and components for refineries, chemical plants, and other industrial facilities. While there are many types of advanced NDT, this article will focus on the use of acoustics and electromagnetism as the bases for conducting examinations. NDT plays a critical role in ensuring that equipment units, their components, and other complex systems perform various functions in a reliable, safe, and cost-effective manner. Advanced NDT techniques have been developed to discover, characterize, measure, and document corrosion, wear, cracks, and flaws in equipment such as pressure vessels and piping systems, which might otherwise leak and cause catastrophic failures.
Drivers of Advanced NDT
The drivers for the development and use of advanced NDT technologies in the inspection industry include, but are not limited to:
- Performing inspections on-stream (reduces risks associated with physical entry) instead of necessitating entry (adds risk and cost)
- For the safety of facility workers and the general public. More efficient inspections, higher quality readings, and easier management of inspection data empowers owner-operators to make better run/repair/replace/inspect decisions and lowers the probability of leaks and catastrophic failure. For example, advanced techniques like phased array ultrasonic testing (PAUT) and time of flight diffraction (TOFD) have proven to be much more effective at detecting, characterizing, and sizing cracks and corrosion than conventional NDT methods. This in turn enables more accurate fitness for service calculations and equipment end of useful life decision making.
- For enhanced reliability. Implementing advanced NDT techniques ensure continuous and unconstrained operations to meet performance requirements at an optimum cost for many of the same reasons as cited in bullet #2.
- For timely compliance with industry codes & standards and regulations. By using on-stream inspection technologies, owner-operators may not have to wait until their next shutdown to complete an assessment.
- For effective risk-based inspection. Advanced NDT can be used to predict and avoid unplanned equipment outages.
- To create a permanent documented record of NDT signals, images and results for record keeping and to compare damage progression at subsequent inspections
Advanced NDT methods provide an excellent balance between quality control and cost effectiveness. State-of-the-art technologies are applied to assess the current condition of equipment and provide more accurate input for estimating the future condition. The data obtained can then be used to calculate fitness-for-service and remaining life of equipment, and help operators develop realistic strategies for managing equipment and extending asset life cycles.