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Showing papers on "Time-of-flight diffraction ultrasonics published in 2013"


Journal ArticleDOI
TL;DR: Higher order wavelets are used for analyzing the de-noising performance for TOFD signals obtained from Austenitic Stainless Steel welds and it is observed that higher orderWavelet Transform based thresholding techniques have been applied largely for de- noising of ultrasonic signals.

47 citations


Journal ArticleDOI
TL;DR: In this article, the authors used the phased array technique to inspect a full-scale model of a pressure vessel section, which contains artificial test reflectors located in the weld and in the cladding region as well.
Abstract: Defect sizing is required for a quantitative assessment of the quality and reliability of safety relevant components and materials using ultrasonic non-destructive testing. The SAFT (Synthetic Aperture Focussing Technique) and the TOFD technique (Time Of Flight Diffraction) are such promising sizing candidates, extracting more information from the raw ultrasound echo data and the corresponding crack tip response. In this work the phased array technique is used to inspect a clad mock-up model of a pressure vessel section. The full scale model contains artificial test reflectors which are located in the weld and in the cladding region as well. The defects—representing typical flaws at a very early stage—are analysed with different frequencies, beam angles and directions of incidence. For the reconstruction of reflector indications a SAFT algorithm is applied to the phased array measurement results. Additionally the reflectors are analysed by means of the TOFD technique, using different beam angles at the same time. Both analysis methods are performed using different directions of incidence considering the complex cladding structure underneath the inner surface of the mock-up model. A direct comparison of the SAFT and TOFD techniques shows that, besides the clarity of the results, the detection and sizing capabilities of SAFT are far better.

26 citations


Journal ArticleDOI
TL;DR: In this article, a three-fold reflected longitudinal wave whose propagation path in the testing piece looks like the letter "W" was used to locate SBD, and mathematical models were developed to locate the SBD tip with the buried depth of 1 mm.
Abstract: Ultrasonic time of flight diffraction (TOFD) suf- fers from the shortcoming of lack of near surface resolution, primarily owning to the superposition of the lateral wave and the shallow buried defect (SBD) wave, and the insen- sitive region beneath the inspection surface because of the restricted beam width of the probes. This paper presents a method for the detection of SBD based on conventional TOFD. The method is named as TOFDW because it employs a three-fold reflected longitudinal wave whose propagation path in the testing piece looks like the letter "W". Based on Pythagoras's theory, mathematical models are developed to locate SBD. In TOFDW mode, the time difference between the lateral wave and the SBD wave can be enlarged greatly so that they would never be superposed. In addition, through reflecting the incident longitudinal wave by bottom surface, the near surface region of the testing piece is covered with an intense acoustic field, making TOFDW free of the restriction of the probes' beam width. These contribute to the improve- ment of the near surface resolution. The experiments show that with the proposed TOFDW and mathematical models, the artificial defect tip with the buried depth of 1 mm can be detected, and the tips can be measured within an error of 0.3 mm; the weld defect with the buried depth of 2 mm can be identified effectively, and the location can be measured within an error of 0.5 mm.

14 citations


Patent
10 Oct 2013
TL;DR: In this paper, a method of detecting and determining the size of fatigue cracks in steel components was proposed, consisting of analyzing the component using a Time of Flight Diffraction (TOFD) ultrasonic technique to locate the crack tip and calculating the distance between the tip and the crack corner trap.
Abstract: A method of detecting and determining the size of fatigue cracks in steel components comprising: analyzing the component using a Time of Flight Diffraction (TOFD) ultrasonic technique to locate the crack tip; analyzing the component using a Phased Array Sectorial (PAS) ultrasonic technique to locate the crack corner trap; and calculating the distance between the crack tip and the crack corner trap to determine the size of the crack.

11 citations


Patent
07 Aug 2013
TL;DR: In this article, an ultrasonic TOFD (Time of Flight Diffraction) detection method for weld defects based on a linear frequency modulation technology, relating to the ultrasonic detection of weld defects, is presented.
Abstract: The invention discloses an ultrasonic TOFD (Time of Flight Diffraction) detection method for weld defects based on a linear frequency modulation technology, relating to an ultrasonic detection method for weld defects. The method solves the problem that in the existing ultrasonic detection for large-thickness welding structures, the signal propagation distance and the resolution ratio are mutually contradicted. The method comprises the following steps that: a digital signal generator produces a wideband (Linear Frequency Modulation) LFM pulse signal, and the wideband LFM pulse signal is amplified through a linear power amplifier so as to have corresponding energy for exciting an ultrasound transmitting probe; the ultrasound transmitting probe after being excited produces forced vibration and radiates ultrasonic waves to a test piece; when a control computer executes an acquisition command, a receiving probe receives a detection signal at a corresponding position, and the receiving of the detection signal is completed by a wideband signal acquisition card; and the computer carries out matched filtering processing on the received signal, so that a pulse compression signal is obtained, and according to the time that each wave reaches, the buried depth of a defect can be calculated according to a formula. The method disclosed by the invention is used for detecting weld defects.

10 citations


Patent
03 Apr 2013
TL;DR: In this paper, a contact type ultrasonic non-destructive testing straight-line automatic scanning device was used for automatically detecting a straight line welding line defect and welding residual stress, where a magnetic type base can be used for conveniently adsorbing a detection device on a welding line region to be detected, and detected position information is recorded and fed back by a photoelectric encoder.
Abstract: The invention relates to a contact type ultrasonic non-destructive testing straight-line automatic scanning device. The device is mainly used for automatically detecting a straight-line welding line defect and welding residual stress. A magnetic type base can be used for conveniently adsorbing a detection device on a welding line region to be detected; a transverse beam of the detection device is formed by a motor and a straight-line guide rail; the motor drives a slide block for mounting a detection sensor to move along the straight-line guide rail; the sensor can be a residual stress detection sensor, a TOFD (Time Of Flight Diffraction) detection sensor and a surface defect detection sensor; and detected position information is recorded and fed back by a photoelectric encoder. The device can be applicable to automatic detection on the welding line region of a plate type welding component, can realize the automatic detection on a welding line of a curve-surface welding component including a pipeline and the like, and improves the detection efficiency.

10 citations


Proceedings ArticleDOI
24 Jan 2013
TL;DR: In this article, a combination of phased arrays and equivalent flaw sizing methods are proposed as the foundation for a new generation of sizing methods that go beyond TOFD sizing, which is one of the most common sizing methods in practical use by industry today.
Abstract: The time-of-flight diffraction (TOFD) technique is one of the most common sizing methods in practical use by industry today. This method was developed over 40 years ago and is based on the technology and state of knowledge present at that time. A combination of phased arrays and equivalent flaw sizing methods are proposed as the foundation for a new generation of sizing methods that go beyond TOFD sizing.

7 citations


Proceedings ArticleDOI
24 Jan 2013
TL;DR: In this article, the authors used ultrasonic phased array transducers to extend traditional time-of-flight diffraction (TOFD) crack sizing, resulting in more quantitative information about the crack being obtained.
Abstract: Ultrasonic phased array transducers can be used to extend traditional time-of-flight diffraction (TOFD) crack sizing, resulting in more quantitative information about the crack being obtained. Traditional TOFD yields a single length parameter, while the equivalent flaw time-of-flight diffraction crack sizing method (EFTOFD) described here uses data from multiple look-angles to fit an equivalent degenerate ellipsoid to the crack. The size and orientation of the equivalent flaw can be used to estimate the actual crack size.

7 citations


Patent
06 Feb 2013
TL;DR: In this article, a method for detecting ultrasonic TOFD (time of flight diffraction) imaging of a shaft pressing position is proposed, which is simple and easy to operate and applicable to detection of solid shaft workpieces.
Abstract: A method for detecting ultrasonic TOFD (time of flight diffraction) imaging of a shaft pressing position includes the following steps of firstly, mounting two probes and an encoder, disposing the two probes on two sides of the shaft pressing position respectively, utilizing one of the probes as a transmitting probe and the other as a receiving probe, attaching the transmitting probe and the receiving probe on the shaft surface and connecting the transmitting probe, the receiving probe and the encoder with corresponding ports of an ultrasonic TOFD imaging detector; and then starting the ultrasonic TOFD imaging detector to detect the shaft pressing position. During detecting, positions of the transmitting probe and the receiving probe are kept constant, a shaft rotates freely, the ultrasonic TOFD imaging detector records echo signals and position information thereof, and the echo signals are displayed in an image manner. The method for detecting ultrasonic TOFD imaging of the shaft pressing position can quickly, effectively and completely detect the shaft pressing position and is simple and easy to operate and applicable to detection of solid shaft workpieces, labor intensity is reduced and detecting efficiency is improved.

6 citations


Journal ArticleDOI
TL;DR: The results show that the proposed method could effectively enhance SNR of TOFD images and improve the ability to identify weld defects of materials.
Abstract: Influenced by random noises from inhomogeneous material scattering and fluctuation of detected electric signals, the signal-to-noise ratio (SNR) of ultrasonic time-of-flight-diffraction (TOFD) image decreases significantly. For the noise reduction of TOFD images, several D-scanned TOFD images with different distribution of noise characteristics are obtained through repeating detection and slightly and randomly changing the probe’s initial position each time. The registered images then are processed by shift-and-add (SAA) technique to reduce the noise level of the TOFD images. Besides, correlation image registration algorithm based on optimization method was established to avoid the shift of TOFD images due to slight change of probe’s initial position. Noises in the registered images show stochastic behavior at the same position. In order to verify reliability of the algorithm, an experimental TOFD detection system for weld defects has been designed to acquire and experiment with TOFD images. The experiment results have been evaluated in terms of cross correlation coefficient, SNR and standard variance of images. The results show that the proposed method could effectively enhance SNR of TOFD images and improve the ability to identify weld defects of materials.

6 citations


Journal ArticleDOI
TL;DR: In this paper, a linear elastic fracture mechanics (LEFM) based approach has been used to predict crack propagation in a widely used pressure vessel steel, where all the controlling parameters have been replaced by statistical distributions obtained from experiment, namely, crack growth tests, hardness tests, tensile tests and Charpy tests.


Patent
30 Jan 2013
TL;DR: In this paper, an inclined TOFD (time of flight diffraction) chip, a common pulse reflection ultrasonic chip, and a Common Pulse Reflection Ultrasonic Chip (CPRU) are sequentially inlaid on the organic glass wedge from the right end to the left end of the organicglass wedge, and power line and a power line port are used for being connected with a piezoelectric chip.
Abstract: The utility model discloses a compound probe for detecting defects of weld joints of workpieces. The compound probe comprises a long cylindrical shell. An organic glass wedge is arranged in the middle of the shell, a damping block is arranged on the periphery of the organic glass wedge and is positioned in the shell, an inclined TOFD (time of flight diffraction) chip, a common pulse reflection ultrasonic chip a and a common pulse reflection ultrasonic chip b are sequentially inlaid on the organic glass wedge from the right end to the left end of the organic glass wedge, and a power line and a power line port which are used for being connected with a piezoelectric chip are arranged at the left end of the shell. The TOFD chip and the common pulse reflection ultrasonic chips are combined to form the TOFD and common pulse reflection ultrasonic compound probe, the interlayer defects of the weld joints are accurately positioned by the TOFD chip, regions of upper and lower surfaces of the weld joints are detected by a common pulse reflection ultrasonic probe, and the problem of surface 'dead zones' in the TOFD detection technology can be solved.

Patent
09 Jan 2013
TL;DR: In this paper, a pressure container weld transverse cracking TOFD (time of flight diffraction) detection scanner is used for detecting a workpiece to be detected, and the beam transmitted by the probe forms a certain included angle with the transversal cracking inside the workpiece.
Abstract: The utility model relates to a pressure container weld transverse cracking TOFD (time of flight diffraction) detection scanner. The scanner comprises a main frame, wherein magnetic wheel mechanisms are respectively arranged on four corners of the main frame, and each magnetic wheel mechanism comprises a magnetic wheel and a magnetic wheel bracket which is used for arranging the magnetic wheel on a corresponding position of the main frame; the main frame is provided with one or more probe loading arms, and part or all of the probe loading arms is provided with a probe; and the beam transmission direction of the probe and the horizontal direction form an included angle of between 30 and 60 degrees, and the probe comprises a TOFD probe. When the pressure container weld transverse cracking TOFD detection scanner is used for detecting a workpiece to be detected, the beam transmitted by the probe forms a certain included angle with the transverse cracking inside the workpiece to be detected; and after the beam transmitted by the probe is beat to the transverse cracking, the probe can receive more beam energy, and the transverse cracking inside the workpiece to be detected can be detected effectively.

Book ChapterDOI
01 Jan 2013
TL;DR: The task of this work is to minimize the volume of data to process replacing ultrasonic images type TOFD by sparse matrix, as there is no reason to store and operate on a huge number of zeros, especially when large structures are inspected.
Abstract: In recent years, research concerning the automatic interpretation of data from non destructive testing (NDT) is being focused with an aim of assessing embedded flaws, quickly and accurately in a cost effective fashion. This is because data yielded by NDT techniques or procedures are usually in the form of signals or images which often do not present direct information of the structure’s condition. Signal processing has provided powerful techniques to extract the desired information on material characterization and defect detection from ultrasonic signals. The imagery available can add additional and significant dimension in NDT information. The task of this work is to minimize the volume of data to process replacing ultrasonic images type TOFD by sparse matrix, as there is no reason to store and operate on a huge number of zeros, especially when large structures are inspected. A combination of two types of neural networks, a perceptron and a Self Organizing Map (SOM) of Kohonen is used to distinguish between a noise signal from a defect signal in one hand, and to select the sparse matrix elements which correspond to the locations of the defects in the other hand. This new approach to data storage will provide an advantage for the implementations on embedded systems as it allows the normalization of the sparse matrix by fixing its dimension.

Proceedings ArticleDOI
21 Feb 2013
TL;DR: The proposed NDT method is a interface predictive coding & is one of the most powerful image coding techniques that can control the redundancy and blur and can identify microscopic casting defects and cracks automatically, which may be even internal fault in nature and measure them by intelligent object detection and feature extraction tools.
Abstract: Quality assurance is the systematic monitoring and evaluation of the various aspects of a product to maximize the probability that minimum standards of quality are being attained by the production process. Deviations from the normal quality that impair the operating characteristics of a metal or product and lead to a reduction in grade or to rejection of products should be considered as defects. To achieve zero defects (“Zero ppm”) output cost-effectively, manufacturers are making the commitment to move to online, automated Non Destructive Testing (NDT) methods. One of the major difficulties with real-time image acquisition is redundancy due to continuous scanning of scenes. The proposed NDT method is a interface predictive coding & is one of the most powerful image coding techniques that can control the redundancy and blur and can identify microscopic casting defects and cracks automatically, which may be even internal fault in nature and measure them by intelligent object detection and feature extraction tools. The paper introduces the Four Step Search matching based automated visual quality inspection and NDT employed using intelligent object detection which have many advantages over existing methods and feature extraction in ultrasonic ToFD scan images as a tool in the automated visual inspection and NDT.

Proceedings ArticleDOI
24 Jan 2013
TL;DR: In this paper, boundary reflections in the path from transmitter to receiver are used for the inspection of welds to determine the type, position, and size of defects, and these images can be combined into a single figure providing a section view of the weld.
Abstract: Ultrasonic imaging can be applied for the inspection of welds to determine the type, position, and size of defects. By including boundary reflections in the path from transmitter to receiver, defects in the weld can be imaged from different directions using both reflection and diffraction signals. These images can be combined into a single figure providing a section view of the weld. The geometrical configuration must be taken into account for proper alignment of the sub-images. These sub-images can be linked to conventional ultrasonic inspection techniques, such as the phased array tandem technique and time of flight diffraction.

Patent
16 May 2013
TL;DR: In this article, the authors proposed a TOFD-based flaw detection method for a weld zone using a transmission-side probe 12 and a reception-sensor probe 11 arranged across the weld zone 60.
Abstract: PROBLEM TO BE SOLVED: To provide a flaw detection device for a nozzle and its method that can easily calculate a position of a flaw of a nozzle connected by welding in a TOFD method.SOLUTION: A flaw detection device for a weld zone using a TOFD method includes a transmission-side probe 12 and a reception-side probe 11 arranged across a weld zone 60. The transmission-side probe 12 transmits an ultrasonic beam to the weld zone 60 at 60° and the reception-side probe 11 receives a diffracted wave of the ultrasonic beam from a flaw 70 of the weld zone 60. The device further includes: elliptic track calculation means for calculating an elliptic track such that the ultrasonic wave from the transmission-side probe 12 to the reception-side probe 11 is equal in propagation path length; echo height calculation means for calculating echo heights of a plurality of diffracted waves on the calculated elliptic track by changing a plurality of reception angles of the reception probe; and flaw position calculation means for calculating a position of a flaw of the weld zone on the basis of the elliptic track calculated by the elliptic track calculation means and the echo heights calculated by the echo height calculation means.

Journal ArticleDOI
TL;DR: Ultrasonic TOFD signals obtained from Austenitic Stainless Steel weldments are analyzed using Fourier Transforms, widely used in the analysis and de-noising of signals of different kind.
Abstract: Non Destructive testing of structural materials is an important activity in many industries. Ultrasonic NDT is one such method widely used in this field. Pulse Echo and Through Transmission are conventional testing techniques which use reflected and transmitted sound energy respectively. But these techniques are highly dependent on defect orientation. Time of Flight Diffraction (TOFD) is a recent method which uses diffracted sound energy to detect the defects and is independent of orientation of the defects in the material. TOFD signals are dominated by noise arriving from various sources namely instrumental noise, material (structural) noise, thermal noise etc. Signal processing is an important step in the evaluation of the signals for detecting, positioning and characterizing the defects. Fourier Transform is widely used in the analysis and de-noising of signals of different kind. In this paper Ultrasonic TOFD signals obtained from Austenitic Stainless Steel weldments are analyzed using Fourier Transforms.

Patent
20 Mar 2013
TL;DR: In this paper, a time of flight diffraction (TOFD) scanning checking frame with magnetic wheels is presented, which adopts the magnetic wheels as the idler wheels, ensuring stability of a scanning checking device, ensuring quality of scanning checking images and achieves the aim of movable scanning checking by means of the elastic coupling characteristics.
Abstract: The utility model discloses a time of flight diffraction (TOFD) scanning checking frame which comprises a scanning checking main beam Two parallel 'herringbone' supports are installed under the scanning checking main beam, the axis of the scanning checking main beam is perpendicular to a plane of the 'herringbone' supports, two idler wheels are installed under each 'herringbone' support, the axis of the idler wheels is parallel to the axis of the scanning checking main beam, a coder and a probe are installed on the main beam, and the idler wheels are magnetic wheels The TOFD scanning checking frame adopts the magnetic wheels as the idler wheels, ensures stability of a scanning checking device, ensures quality of scanning checking images and achieves the aim of movable scanning checking by means of the elastic coupling characteristics

01 Jan 2013
TL;DR: In this paper, a sparse deconvolution was proposed to enhance significantly the resolution of the original time trace, making it possible to determine the amplitudes and the arrival times of the wave packets contained in the original temporal sequence.
Abstract: In ultrasonic nondestructive testing, the reflection sequence always overlapped or immersed in noisy. A sparse deconvolution was proposed to enhance significantly the resolution of the original time trace, making it possible to determine the amplitudes and the arrival times of the wave packets contained in the original time sequence. With the purpose of ensuring sparsity, Compressed sensing (CS) and Orthogonal matching pursuit (OMP) were used for pulse-echo signal reconstruction to obtain sparser distortion function for sparse deconvolution. Simulated results and experimental verification which performed on time of flight diffraction (TOFD) specimens demonstrated the proposed method.

Patent
24 Apr 2013
TL;DR: In this article, the authors proposed a non-destructive TOFD (time-of-flight diffraction) detection scanning rack, which consists of a main scanning rack body, a probe component, a roller component, an encoder component, and a circular ring embedded on the main scan rack body.
Abstract: The utility model belongs to a nondestructive TOFD (time-of-flight diffraction) detection device and particularly relates to a TOFD (time-of-flight diffraction) ultrasonic detection scanning rack. The scanning rack comprises a main scanning rack body, a probe component, a roller component, an encoder component, a circular ring embedded on the main scanning rack body, and a straight rod arranged on the circular ring. One end surface of the circular ring is provided with a T-shaped groove I and angle scales. Connecting rods and the straight rod forming the main scanning rack body are respectively provided with two T-shaped grooves II of which openings are back to each other; and each T-shaped groove II is internally provided with a slider II which is provided with a threaded hole. The straight rod is provided with connecting holes in the direction perpendicular to the T-shaped grooves II; the center distance of the two connecting holes is equal to the central diameter of the T-shaped groove I in the circular ring; and the straight rod is connected with a slider I through a screw. The probe component, the roller component and the encoder component are connected with the sliders II through screws. The scanning rack is simple and reasonable in structure design and can be used for not only singly but also simultaneously carrying out parallel scanning and oblique scanning. Due to the adoption of a modularized structure in the scanning rack, spare parts can be conveniently disassembled and replaced.

Proceedings ArticleDOI
25 Jul 2013
TL;DR: Analysis of the restored image indicate that the Symlets family with the suitable thresholding has Higher Peak Signal to Noise Ratio(PSNR) value than the Coiflets wavelet family.
Abstract: Time-of-Flight Diffraction (TOFD) is an advanced ultrasonic inspection technique best suited for inspection especially inservice wherein the focus is on detection of cracks and linear indications which can propagate during service. The technique is widely used in process industries and also in strategic sector like nuclear. In the case of ISI in nuclear industry, the main difficulties likely to arise during such inspection are the high temperature (during shut down) and the background radiation. With the advent of high temperature probes, this limitation can be overcome. However, a fundamental factor which still is a cause for concern is the degradation of the signal to noise ratio due to thermal noise. Experiments conducted by the authors reveal that the contrast of acquired TOFD Images reduces progressively with increasing temperatures. As the temperature increases beyond 373K, the noise makes interpretation of images difficult and thus possibility of linear defects getting missed out arise. It is well known that the wavelets can be effectively employed for denoising. Wavelets have also been applied in general for denoising UT signals. However, its application for UT signals from stainless steel and which is at high temperature has not been attempted so far. In this paper, we explore the innovative application of wavelet thresholding for denoising applications due to its greater flexibility. Analysis of the restored image indicate that the Symlets family with the suitable thresholding has Higher Peak Signal to Noise Ratio(PSNR) value than the Coiflets wavelet family.

Proceedings ArticleDOI
14 Jul 2013
TL;DR: In this paper, the authors present the development of more advanced testing methods, with examples of applications on pressure vessel and piping components, and show that these technologies are now available in the market with affordable prices, to test more reliably and faster the health of mechanical components.
Abstract: The non-destructive testing techniques (NDT) are now undergoing significant changes associated with the development of new sensors and digital techniques for storing and processing information.Thus, new ultrasonic methods now provide a view of the entire component in the form of a traceable image. These new methods include ultrasonic TOFD methods (to inspect metal products), and the Phased Array method (metallic and composite products), which can image the inside of components. The simulation of ultrasonic testing brings a strong contribution in ultrasonic inspection preparation.Another major trend of the development of NDT methods is the rise of active thermal infrared methods, enabling high resolution imaging of surface and near surface defects of components.A remarkable application of new radiographic technology consists also in Computed Tomography, which now allows 3D imaging within the mechanical components.These technologies are now available in the market with affordable prices, to test more reliably and faster the health of mechanical components. Thus, it helps to increase the quality of components, especially in the Pressure Vessel and piping industry, and to improve the safety of industrial pressure equipment.Developments in the more advanced testing methods are presented, with examples of applications on pressure vessel and piping components.Copyright © 2013 by ASME

Patent
21 Nov 2013
TL;DR: In this article, the authors proposed a TOFD-based method to increase the SN ratio of diffracted waves from foreign matter (for example cracks) by reducing noise generated inside a test body or on a surface layer thereof.
Abstract: PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detection method and device by a TOFD method, capable of remarkably increasing an SN ratio of diffracted waves from foreign matter (for example cracks) by remarkably reducing noise generated inside a test body or on a surface layer thereof.SOLUTION: (1) By a sector scanning of a phased array probe 15b, the direction of an incident ultrasonic wave beam (incident wave S1) is changed, intersecting axes point depth D from the surface of a test body 3 at intersecting axes point X where central axes of ultrasonic wave beams of a transmission-side probe 12 and a reception-side probe 14 are intersected with each other is sequentially changed, and a plurality of diffracted waves S2 corresponding to a plurality of intersecting axes point depths D are received by the reception-side probe 14. (2) A combined waveform S3 of the diffracted waves S2 are created by overlapping a plurality of diffracted waves with one another.

Journal ArticleDOI
TL;DR: In this article, three propylene spherical tanks which have both the same manufacturing parameters and conditions have been assessed based on risk assessment and non-destructive testing technology, and the results of inspection verifies the reliability of risk assessment, which can also provide significant guidance for future complete equipment inspection.
Abstract: Three propylene spherical tanks which have both the same manufacturing parameters and conditions have been assessed based on risk assessment and non-destructive testing technology. One of the spherical tanks is stopped for comprehensive inspection, and the result of inspection verifies the reliability of risk assessment, which is applied to other two unopened propylene spherical tanks. Meanwhile, in order to make overall inspection level meet the requirements of the risk assessment and so reduce spherical tanks assessing risk, ultrasonic diffraction detection (TOFD) with high detection rate and fluorescent magnetic surface detection technology are adopted to ensure comprehensive test meeting the risk assessment requirements, which can also provide significant guidance for future complete equipment inspection.

Patent
14 Aug 2013
TL;DR: In this article, the utility model discloses a time of flight diffraction (TOFD) scanning rack and a TOFD detection device, which consists of a first scanning rod and a second scanning rod which is rotationally connected with the first scanning rods through a connecting piece, so that the TOFD scanning rack can change the angle according to the needs.
Abstract: The embodiment of the utility model discloses a time of flight diffraction (TOFD) scanning rack and a TOFD detection device The TOFD scanning rack comprises a first scanning rod, and a second scanning rod which is rotationally connected with the first scanning rod through a connecting piece By adoption of the technical means that the TOFD scanning rack consists of the first scanning rod and the second scanning rod which is rotationally connected with the first scanning rod through the connecting piece, so that the TOFD scanning rack can change the angle according to the needs, a special workpiece can be detected, the detection range of a TOFD is greatly widened, and the production output is improved

Book ChapterDOI
01 Jan 2013
TL;DR: In this paper, the authors presented techniques developed for enhancing the accuracy of sizing and positioning of off-axis weld defects in ultrasonic time-of-flight diffraction (TOFD) D-scan data.
Abstract: Despite the recent popularity of ultrasonic time-of-flight diffraction (TOFD) as a reliable non-destructive testing technique for the inspection of weld defects in steel structures, the critical stages of data processing and interpretation are still performed manually. This depends heavily on the skill, experience, alertness and consistency of a trained operator, and is subject to inevitable human errors due to reduced alertness arising from operator fatigue and visual strain when processing large volumes of data. This paper presents techniques developed for enhancing the accuracy of sizing and positioning of off-axis weld flaws in TOFD D-scan data as an essential stage in a comprehensive TOFD inspection and interpretation system to aid the operator by automating some aspects of the processing and interpretation. Data manipulation and post-processing techniques have been specifically developed for the sizing of off-axis weld defects in TOFD data, significantly reducing the sizing and positioning errors. The mode-converted waves are utilised to enhance positional accuracy of flaws. The results achieved so far have been promising in terms of accuracy, consistency and reliability.

Journal Article
TL;DR: In this article, a multidisciplinary structural health monitoring (SHM) system composed of acoustic emission, strain measurements, and vibration measurement has been applied to a test steel bridge deck under a fatigue loading in a lab environment.
Abstract: Fatigue cracks in orthotropic bridge decks are an important cause for the necessary renovation of existing bridges. Parallel utilization of various technologies based on different physical sensing principles can potentially maximize the efficiency of structural health monitoring (SHM) systems for these complex structures. A multidisciplinary SHM system composed of acoustic emission, strain measurements, and vibration measurement has been applied to a test steel bridge deck under a fatigue loading in a lab environment. Having the main focus on acoustic emission and strain measurement, the present paper provides an evaluation of the performance of the SHM system in terms of detection of the crack initiation, localization, and growth. During the destructive test, the strain measurement was employed as a local monitoring method, and acoustic emission was utilized as a local/global monitoring scheme. The monitoring performance was validated using visual inspection and time of flight diffraction (TOFD) measurements. Some of the main observations in this study are: (i) good agreement between the estimated crack size based on the strain measurement and TOFD measurement, (ii) the earlier detection of the crack activity by acoustic emission compared to the 10% deviation of the strain measured at a few millimeters away from the crack initiation location, and (iii) localization of multiple active cracks by acoustic emission.

Patent
14 Aug 2013
TL;DR: The embodiment of the utility model discloses a time of flight diffraction (TOFD) probe structure and a TOFD detection device as discussed by the authors, which comprises an angle wedge block and a probe protection block fixedly arranged on the angle wedge blocks.
Abstract: The embodiment of the utility model discloses a time of flight diffraction (TOFD) probe structure and a TOFD detection device. The TOFD probe structure comprises an angle wedge block and a probe protection block fixedly arranged on the angle wedge block, wherein a TOFD probe is arranged in the probe protection block. According to the embodiment of the utility model, due to a technical measure that the angle wedge block is added on the probe protection block, change of a relative angle of a probe sound bundle caused by structural pieces can be prevented by the angle wedge block, so that detection of lack of the structural pieces and the accuracy of parameters are guaranteed; an absorption ultrasonic material can effectively reduce noise waves, so that lack judgment is facilitated; and the quality of the structural pieces is effectively controlled.