A Study on Ultrasonic Testing for Nondestructive Evaluation of Thermal Fatigue Crack in Pipelines

Yi, Won; Lee, Min Rae; Lee, Joon Hyun; Choi, Sang Woo; Lee, Bo Young

doi:10.4028/www.scientific.net/kem.321-323.747

Cited by 4 publications

(3 citation statements)

References 6 publications

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“…The stable and reliable signal is always desired for ultrasonic inspection to evaluate the defect of weld. Since TOFD is a very sensitive technique [16][17][18], apart from the inherent factors like frequency, resolution, beam spread and the presence of material noise, the coupling state between the wedge and the surface work piece has a great effect on the signal acquisition [19]. For this reason, a surface adaptive probe holder with 3 DOFs for the weld inspection robot was designed.…”

Section: Ultrasonic Inspection System With Tofd Methodsmentioning

confidence: 99%

Non-contacted Permanent Magnetic Absorbed Wall-climbing Robot for Ultrasonic Weld Inspection of Spherical Tank

2019

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A novel wall-climbing robot for the onsite weld inspecting of spherical tank with Time of Flight Diffraction (TOFD) method has been developed, in order to liberate operators from dangerous and heavy working environment. Patented non-contacted permanent magnetic absorbed technology was adopted to realize reliable and flexible all-position moving along the weld seam on the surface of spherical tank. To ensure stable coupling for TOFD test, a surface adaptive probe holder which can provide constant contact force, have been particularly designed. Equipped with a visual sensing based weld seam tracking unit and industrial PC station, the robot could perform automatic flaw detection remotely even in the darkness environment. Onsite ultrasonic weld inspections have been carried out on a 4000m3 spherical tank with 28mm in thickness. It is verified that the robot could accomplish tasks in any position and the acquired TOFD images satisfy the requirements of engineering evaluation.

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Section: Ultrasonic Inspection System With Tofd Methodsmentioning

confidence: 99%

Non-contacted Permanent Magnetic Absorbed Wall-climbing Robot for Ultrasonic Weld Inspection of Spherical Tank

2019

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“…In recent years, studies have been conducted to apply various testing methods for a more accurate evaluation of thermal fatigue cracks. These include studies on the time-offlight diffraction (TOFD) technique, which evaluates flaws using the diffraction signals of ultrasounds [12,13], and the evaluation of the flaw depth using eddy current inspection (ECT) [14,15]. Testing methods using TOFD or ECT have difficulties in analyzing signals according to the geometry of the welds and quantitatively evaluating the flaw height.…”

Section: Introductionmentioning

confidence: 99%

Reliability Analysis of PAUT Based on the Round-Robin Test for Pipe Welds with Thermal Fatigue Cracks

Kang,

Choi,

Lee

et al. 2023

Materials

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Thermal fatigue cracks occurring in pipes in nuclear power plants pose a high degree of risk. Thermal fatigue cracks are generated when the thermal fatigue load caused by local temperature gradients is repeatedly applied. The flaws are mainly found in welds, owing to the effects of stress concentration caused by the material properties and geometric shapes of welds. Thermal fatigue pipes are classified as targets of risk-informed in-service inspection, for which ultrasonic testing, a volumetric non-destructive testing method, is applied. With the advancement of ultrasonic testing techniques, various studies have been conducted recently to apply the phased array ultrasonic testing (PAUT) method to the inspection of thermal fatigue cracks occurring on pipes. A quantitative reliability analysis of the PAUT method must be performed to apply the PAUT method to on-site thermal fatigue crack inspection. In this study, to evaluate the quantitative reliability of the PAUT method for thermal fatigue cracks, we fabricated crack specimens with the thermal fatigue mechanism applied to the pipe welds. We performed a round-robin test to collect PAUT data and determine the validity of the detection performance (probability of detection; POD) and the error in the sizing accuracy (root-mean-square error; RMSE) evaluation. The analysis results of the POD and sizing performance of the length and depth of thermal fatigue cracks were comparatively evaluated with the acceptance criteria of the American Society of Mechanical Engineers Code to confirm the effectiveness of applying the PAUT method.

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“…Traditionally, it has often been performed using manual bulk wave ultrasonic NDE methods such as time-of-flight diffraction (TOFD) from the exterior of the pipe. 4 However, this method is time-consuming as the inspected volume for a single test is small and the transducers must be repositioned for every test. It can also be difficult to achieve full coverage in more complex geometries.…”

Section: Introductionmentioning

confidence: 99%

The use of circumferential guided waves to monitor axial cracks in pipes

Rodgers

Mariani

Cawley

2022

Structural Health Monitoring

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Guided wave testing is in routine use to detect corrosion, particularly in the oil and gas sector, but the detection of axial cracking is difficult using the axially propagating waves commonly used for corrosion detection. This paper presents a novel guided wave monitoring technique for the detection of axial cracking in piping. Circumferential SH0 waves, travelling around the circumference were used in a monitoring configuration to detect axial defects in a 6 inch schedule 80 steel pipe. Finite Element (FE) analysis showed that both the defect reflection and the decline in the transmitted SH0 wave can be used for defect detection. Baseline subtraction was utilised to produce residual signals that can be better analysed for small defect reflections. The Root-Mean-Square (RMS) of the residual signal after baseline subtraction was found to be the most satisfactory means of monitoring defect progression. An amplification effect was identified where the residual signal is compounded by continued interaction with the defect on each revolution of the incident wave. The FE predictions were validated by an experiment in which an Electrical Discharge Machining (EDM) notch was grown in four stages. Temperature compensation using Location Specific Temperature Compensation (LSTC) was applied to the experimental data, allowing residuals to be compared for a ∼10 °C temperature swing over a monitoring period of over 2 months. It was determined that a 10 mm long (∼23% of wavelength), 5 mm deep (∼45% of the wall thickness) defect at an axial offset from the line of the transducers of 1.5 wavelengths (65 mm) would be readily detectable with a very high Probability of Detection (POD) and virtually no chance of a false call. Therefore, this novel guided wave monitoring system for axial crack detection is likely to be attractive for applications in a range of industries for its sensitivity to axial cracking combined with large coverage from a single transducer location.

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A Study on Ultrasonic Testing for Nondestructive Evaluation of Thermal Fatigue Crack in Pipelines

Cited by 4 publications

References 6 publications

Non-contacted Permanent Magnetic Absorbed Wall-climbing Robot for Ultrasonic Weld Inspection of Spherical Tank

Non-contacted Permanent Magnetic Absorbed Wall-climbing Robot for Ultrasonic Weld Inspection of Spherical Tank

Reliability Analysis of PAUT Based on the Round-Robin Test for Pipe Welds with Thermal Fatigue Cracks

The use of circumferential guided waves to monitor axial cracks in pipes

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