NuVision Engineering, Inc. provides an extensive range of NDE services and techniques. These are performed by qualified specialists using advanced examination systems and equipment. We offer field services support for detection, sizing and defect characterization on turbine/generator rotors, retaining rings, piping, vessels and other critical components. Among the services we offer are:
Rotor Boresonic Inspection
Utilizing specially-designed focused ultrasonic transducers enables us to conduct in-focus inspection of the full volume of the critical near bore material in turbine and generator rotors. This approach provides superior resolution and sizing capabilities and significantly reduces the uncertainty in the rotor life assessment process. We offer high flaw detection reliability, much more accurate sizing capabilities and the ability to resolve ligaments between closely clustered reflectors. More accurate data offers clients increased flexibility and confidence in rotor maintenance and reduces the conservatism associated with conventional exams. Our personnel have extensive experience in applying specialized NDE techniques for detecting and sizing flaws in turbine/generator rotor bores.
Time-of-Flight Diffraction (TOFD) Ultrasonic Inspection
TOFD ultrasonic inspection offers dramatic improvements in defect detection and sizing capability and, at the same time, higher reliability and cost savings. TOFD differs from conventional pulse-echo ultrasonic examination in that the reflected energy compared with a reference reflector is not used for the classification of defects. Rather, the actual flaw size is derived from diffracted signals generated in all directions at the extremities of the defect. This results in high measurement accuracy. Defect through-wall dimensions can be determined under practical conditions to within a millimeter and there exists a high probability of detection both for planar as well as volumetric defects. Since its development in the 1970s, we have successfully performed TOFD on vessels and piping welds for many clients. Our techniques for the assessment of creep damage have been refined to detect subtle changes in material structure. This provides our clients with the data to ensure safe and continued operation of their systems.
Micro-map Corrosion Mapping
We have a unique approach to corrosion mapping that eliminates the need for extensive gridding and the use of cumbersome mechanical scanners. This innovative approach, called Micromap, provides comprehensive coverage, rather than point-to-point sampling, and high-quality graphical reporting of erosion/corrosion and wall thinning in a versatile, efficient and cost-effective fashion. Micromap uses a video camera to monitor the position of a hand-held ultrasonic probe and then combines the video position and ultrasonic data to present inspection results in the form of a real-time color graphic "C-Scan" image of the inspection area. Repeatability and reproducibility of wall thinning monitoring from one outage to the next is ensured with the aid of a built-in and variable grid system.
Advantages of Micro-map include:
- Requires no mechanical scanners
- Can be used for the evaluation/detection of FAC in power plants
- Can be used to detect HIC and SOHIC
- Permits the UT imaging of complex geometries such as Ts, valves and bends
- Can generate color composite images by joining individual scan areas to show the overall condition of the inspected item
Retaining Ring Inspection
We use specialized and complementary examination methods developed to provide extremely reliable examinations of generator retaining rings. These methods include ultrasonic (UT) shear waves, inner-surface creeping waves, time-of-flight diffraction UT, and eddy current surface examination. Our retaining ring inspection services offer clients a combination of ultrasonic and eddy current examination methods specially developed and refined for retaining rings, providing higher flaw detection reliability and much more accurate sizing capabilities. Graphical images of ultrasonic and eddy current data provide a clear picture of the condition of a clients' rings and serve as an invaluable baseline for future inspections.
Advantages of the NuVision retaining ring inspection technique include:
- Ability to be performed with rings in place
- Use of eddy current (ET) in lieu of dye-penetrant (PT) method eliminates introduction of moisture onto the ring
- Use of ET in lieu of PT eliminates the risk of arcing the bore, which could lead to intergranular stress corrosion cracking (IGSCC)