Showing papers on "Time-of-flight diffraction ultrasonics published in 2014"

The Pulsed Ultrasonic Backscatter Polar Scan and its Applications for NDT and Material Characterization

Abstract: In a conventional ultrasonic polar scan (UPS) experiment, the amplitude or time-of-flight-diffraction (TOFD) values of the transmitted and/or reflected acoustic pulse are recorded for a wide range of incidence angles, in view of gaining knowledge about the elastic properties at the insonified material spot. Here we apply the pulsed UPS technique and investigate the backscattered signal, resulting in the ultrasonic backscatter polar scan (UBPS). It is shown that a UPBS contains a blueprint of geometrically related features of the insonified material spot which can be of particular interest for various industrial applications. We applied the UBPS for (i) the determination of the stacking sequence of a cross-ply composite laminate, (ii) the semi-quantification of a multidirectional microscopic surface corrugation, (iii) the detection of corrosion in an early stage as well as (iv) the detection and the localization of a closed surface breaking crack.

Time of flight diffraction (TOFD) detection method capable of confirming defect size and location parameters

Abstract: The invention discloses a time of flight diffraction (TOFD) detection method capable of confirming the defect size and the location of a welding seam. The method comprises the steps of firstly arranging a transmitting probe at one side of a welding seam and two receiving probes at the other side of the welding seam, wherein one of the two receiving probes is close to the welding seam; and after that, establishing an elliptical mathematical model, programming by matlab software, and solving by calculation. One receiving probe is additionally arranged, the diffraction echo of the defect end can be received by the two receiving probes while one transmitting probe is used for transmitting, related data information can be calculated and processed, and the accurate position in which diffracted waves are generated can be obtained. For a continuous defect, after the positions of the two ends of the defect are obtained, the defect size and location parameters can be confirmed; after the method is used, the defect size and location parameters can be accurately measured, the data accuracy requirement of security evaluation on some important parts with defects can be met, and surface blind areas can be reduced.

Ultrasonic flaw detection method and ultrasonic flaw detection device

Abstract: PROBLEM TO BE SOLVED: To provide an ultrasonic flaw detection method and an ultrasonic flaw detection device which allow end part echo to be distinctly discriminated by using a phased array TOFD (Time Of Flight Diffraction) method.SOLUTION: An ultrasonic wave is transmitted from a transmission phased array probe 2 so that the ultrasonic wave converges on a desired focus position X, and a diffraction wave of the transmission phased array probe 2 is received by a reception phased array probe 3, and at least one of the transmission phased array probe 2 and the reception phased array probe 3 is moved along a detection object part T with the focus position X fixed, to receive diffraction waves due to a plurality of different refraction angles (α, β) by the reception phased array probe 3, and a flaw detection image based on reception signals due to the different refraction angles (α, β) is displayed.

Non-destructive Testing of Split Sleeve Welds by the Ultrasonic TOFD Method

Abstract: This article deals with the non-destructive ultrasonic testing of split sleeve butt joints by ultrasonic methods. Split sleeve is used to repair gas pipelines with gas leakage. The new ultrasonic methods TOFD and Phased Arrays are compared considering to the selected butt weld configuration. To compare testing methods, ES Beam Tool software was used to prediction of ultrasonic beam spread through weld joint. TOFD technology was selected to butt weld section testing according to the beam spread simulation results. The results of ultrasonic testing by TOFD method were compared with results of macrostructural analysis of weld joint. Controlling the suitability of testing method to planar defect identification, the artificial defects were prepared and tested. The appropriate setting of measuring technique can be predicted from experimental results.

Ultrasonic Testing of Girth Welded Joint with TOFD and Phased Array

Abstract: The article describes the fundamental physical principles of the ultrasonic defectoscopy TOFD (Time of Flight Diffraction) and Phased Array. There is a report from the ultrasonic testing of girth welded joint with ultrasonic flaw detector OmniScan MX2 16:64 PA from the company Olympus NDT. In welded joint were artificaly made three defetcts. Two lack of sidewall fusion (on the left and right side of welded joint) and one crack in axis of welded joint. Both ultrasonic testing were designed in software ESBeamTool 5 from the company Eclipse Scientific, which simulates the geometrical ultrasonic beams spread. At the end, data from both ultrasonic testing were evaluated. The same procedure will be used for the design of ultrasonic inspection TOFD and Phased Array at girth welded joints of gas pipelines.

Multifunctional double-channel welding line ultrasonic testing scanner

Abstract: The invention provides a multifunctional double-channel welding line ultrasonic testing scanner The multifunctional double-channel welding line ultrasonic testing scanner comprises a whole sliding main supporting rod, a filter, a junction box, a handle, a digital encoder, a magnetic wheel set, two corresponding TOFD (Time Of Flight Diffraction) probe systems and two corresponding creeping wave probe supporting systems The scanner has the advantages that firstly, the distance between transverse magnetic wheels is small to be applicable to adjusting a large-range curvature so that the scanner can be used for detecting an elbow welding line with a small diameter; secondly, after the upper-lower displacement of a probe bracket is increased, the scanner can be applicable to scanning butt welding lines of an elbow and large and small heads; thirdly, a probe wedge block is reduced so as to be more applicable to detecting an elbow welding opening; fourthly, a slope climbing probe is mounted so as to carry out once scanning on the dead zone of a scanning surface and improve the working efficiency

Method for reducing near surface blind region in TOFD (Time of Flight Diffraction) detection based on spectral analysis principle

Abstract: The invention discloses a method for reducing a near surface blind region in TOFD (Time of Flight Diffraction) detection based on a spectral analysis principle, belonging to the technical field of ultrasonic non-destructive test. The method is completed by virtue of one set of ultrasonic testing system comprising a TOFD ultrasonic detector, a computer integrating TOFD operating software, a TOFD probe, a scanning device, a calibration test block and a digital oscilloscope. A near surface region in the TOFD detection is scanned, an acquired aliasing time-domain signal including defect information is subjected to spectral analysis, a resonant frequency in an amplitude spectrum is read, a sonic path difference between a direct-through wave and a tip diffracted wave on a defect is figured out in combination with a material longitudinal wave velocity, and the defect burial depth in the near surface blind region is further determined. Compared with other methods for reducing the depth of the near surface blind region, the method has no extra requirements on a hardware system, is not limited by thickness of a to-be-tested workpiece, and has good engineering application value.

TOFD (time of fight diffraction) detection method and TOFD detection system for docking ring welding seams of cylinder

Abstract: The invention discloses a TOFD (time of fight diffraction) detection method and a TOFD detection system for docking ring welding seams of a cylinder. The detection method comprises the following steps: dividing the cylinder into a first to-be-detected area, a second to-be-detected area and a third to-be-detected area in the thickness direction of each welding seam according to the characteristics of the welding seams; arranging a first probe pair to detect the first to-be-detected area, arranging a second probe pair to detect the second to-be-detected area, and arranging a third probe pair to detect the third to-be-detected area; performing D scanning on each to-be-detected area in a circle of the circumferential direction of each welding seam by using the first probe pair, the second probe pair and the third probe pair, and recording the movement distance and D scanning flaw distribution of each probe; continuously and stably moving each probe pair along the axis of each welding seam, repeatedly executing the previous step, performing D scanning on each to-be-detected area in the circle of the circumferential direction of each welding seam on the cylinder step by step, and recording the movement distance and D scanning flaw distribution of each probe. In the way, the flaws of the docking ring welding seams of the cylinder can be accurately detected.

Qualification of a combined ultrasonic inspection tool for detection and sizing of circumferential weld cracks in offshore pipelines

Abstract: The target of inline crack inspection is normally related to the detection of axial cracks (weld cracks, SCC etc.) as axial cracks are usually expected under typical loading conditions in pressurized pipe. Ultrasonic crack inspection tools for this type of cracks have been available for over 20 years and have become a standard application in the ILI business. However, under certain conditions circumferential cracking may occur and the inspection technique needs to be modified accordingly. Especially under offshore conditions with limited pipeline accessibility not only the early detection of crack-like defects is required but also a precise depth sizing is important in order to minimize the risk of crack-related pipeline failure. In order to ensure a high probability of detection together with state-of-the-art depth sizing, a 10″ inline inspection tool was developed for the detection of circumferentially orientated weld cracks. The tool combines the advantages of the pulse-echo technique on the detection side with the excellent capabilities of the TOFD (time-of-flight-diffraction) technique for accurate sizing. Both techniques are implemented into a tethered tool where the pulse-echo unit serves for fast screening while the relatively slow TOFD-unit is used for sizing of any detected crack-like features.In order to qualify the new tool for a special offshore application (inspection of circumferential cracking at welded anode pads) extensive testing was performed using a 10″ test pipeline prepared by Statoil. The test line contained 64 artificial weld defects for reference purposes as well as an unknown number of fatigue cracks in the weld area which were generated by fatigue testing of the corresponding pipes. The tests were full blind tests with no advance knowledge on locations and sizes of the cracks. The sizes of the fatigue cracks (length, depth) were determined by destructive examinations carried out after inline testing. The subsequent comparison of the destructive results with the non-destructive results showed that the specification of the tool with regard to detection and sizing was fully met. In the paper, the inspection concept and the setup of the new tool are described, and the results of the qualification tests are presented.Copyright © 2014 by ASME

T-shaped welded joint TOFD (Time of Flight Diffraction) detection comparison test block

Abstract: A T-shaped welded joint TOFD (Time of Flight Diffraction) detection comparison test block is suitable for the check of an instrument during T-shaped welding seam TOFD detection The comparison test block is formed by cutting a steel board according to the practical welding angle dimension line of a checked welding seam, the thickness of the steel board is greater than the width of a TOFD probe wedge, three through holes being Phi 2 mm in diameter are located in a simulated T-shaped joint region of the comparison test block from top to bottom, which are used for identifying the covering of a TOFD detection acoustic beam, and meanwhile used for regulating the detection sensitivity The comparison test block is easy to process, convenient to carry, and can fully satisfy the T-shaped welding seam TOFD detection demand

A Novel Method for Ultrasonic Evaluation of Horizontal Defects Using Time-of-Flight Diffraction

Abstract: Time-of-flight diffraction method (ToFD) is an amplitude-independent sizing method which is based on the measurement of time-of-flight of defect tip diffracted waves. Although ToFD can measure through-wall length of defect accurately, this method is not capable of measuring horizontal defect size. In this paper, a new ToFD method for evaluating horizontal planar defects is presented. The finite element method (FEM), using the ABAQUS software package, is employed to simulate the ultrasonic wave behavior in the test blocks and its interaction with the embedded planar defects. The phased array technology is also used to model the ultrasonic inspection system parameters. FEM simulation of the new ToFD method for different crack sizes shows that, compared to the conventional ToFD method, the accuracy of results is within acceptable range to use the novel technique for measuring the horizontal planar defects.

TOFD (Time of Flight Diffraction) detection method for butt weld defects of steel structures and middle-thick-walled tubes of power station

Abstract: The invention discloses a TOFD (Time of Flight Diffraction) detection method for butt weld defects of steel structures and middle-thick-walled tubes of a power station. The detection method comprises the steps of: adopting a group of defect reference blocks, and producing defects, which common occur in actual but welded joints, such as cracks, incomplete fusion, incomplete penetration, slag inclusion and pore defect samples, on the defect reference blocks; detecting the defect blocks by using a TOFD detection method, and thereby obtaining TOFD detection maps of the defect blocks; detecting the actual welded joint by using the TOFD detection method, comparing the TOFD detection map in the actual welded joint with the TOFD detection maps of the defect blocks respectively to determine whether the actual welded joint is qualified; through scanning the manual defect blocks, and analyzing and comparing the maps, deficiencies and the TOFD standard blocks are compensated, and reliability and accuracy in nature and quantity determination of defects in the TOFD detection method are further increased.

Ultrasonic TOFD in the Application of Thick Wall Tube Welding Seam Detection Pre-Research

Abstract: This article firstly introduces the ultrasonic TOFD (Time-of-flight - Diffraction) detection technology of detection principle, advantages and disadvantages, and then summarizes the ultrasonic TOFD technique related testing standard, finally combining the reality of tube mill, analyses the pipe material testing near the surface of the blind area and radian impact problems, discusses the ultrasonic TOFD in application prospect in the field of thick wall tube welding seam detection.

Mechanized ultrasonic testing method for curved pipe welding zone

Abstract: The present invention, as an inspection method capable of replacing RT used for inspecting an inner side of a welding zone of a curved pipe, relates to an ultrasonic inspection method for a welding zone of a curved pipe embodying a new concept which can quickly and quantitatively evaluate on defects incapable of being detected under conditions (thickness and irradiating direction) of an object to be tested, which is a weak point demonstrated in the RT, using a phased array ultrasonic testing (PAUT) and a time of flight diffraction (TOFD) at the same time.

Walking equipment used for TOFD testing and application method thereof

Abstract: The invention discloses walking equipment used for TOFD testing, and belongs to the technical field of nondestructive testing The walking equipment comprises a scanning mechanism, a support angle adjusting block, a main machine frame, a walking mechanism, an encoder, an antenna and a main control box The scanning mechanism is fixed onto the support angle adjusting block, the support angle adjusting block is fixedly connected with the walking mechanism, the main machine frame is fixedly connected with the walking mechanism, the main control box is fixedly connected with the walking mechanism and the main machine frame and the antenna is installed on the main control box The invention further provides an application method of the walking equipment According to the walking equipment used for TOFD testing and the application method of the walking equipment, a trailing head of the scanning mechanism is used for automatically controlling the advancing direction of the walking equipment, the advancing track of the walking equipment can be corrected more accurately and timely, and the accuracy of TOFD testing data is effectively improved Through a Zigbee wireless communication protocol, the purpose of remotely controlling the walking equipment is realized, the operation range of the walking equipment used for TOFD testing is greatly widened, and the detecting efficiency is effectively improved

Special scanning frame for monitoring extending of interrupted interlayer of steel plate with TOFD (time of flight diffraction)

Abstract: The utility model discloses a special scanning frame for monitoring extending of an interrupted interlayer of a steel plate with TOFD (time of flight diffraction) The special scanning frame comprises a main beam, scanning brackets and an encoder bracket, wherein the scanning brackets and the encoder bracket are in bolt connection through organic glass blocks and sliding blocks inlaid in the main beam; and the scanning brackets are arranged on the inner side and the outer side of each wing plate with an interrupted interlayer defect The special scanning frame has the advantages that complete synchronization of TOFD probes on the inner sides and the outer sides of the wing plates is guaranteed when TOFD monitors the interrupted interlayer defects of the wing plates, the one-time scanning distance can be the maximum, that is, only half of each wing plate can be scanned once due to blocking of a web; and the special scanning frame is simple in structure and capable of conveniently monitoring extending of the interrupted interlayer of the steel plate

Investigation of Sound Field with Water Immersion TOFD Method Basing on Electron Beam Welding

Abstract: The time and flight diffraction (TOFD) technique has be more and more applied as a well-developed ultrasonic non-destructive testing (NDT) technique in a increasing number of industrial areas such as aeronautics and mechanical industries, therefore, the TOFD technique can be also used to investigate the sound field characteristic curve of artificial defects in welding. The investigations are performed in 2-layered medium (water-steel) with using the finite difference numerical simulation software Wave2000. The receiver group is consisted of several receivers which are immersed in water and have the same frequency, the receivers are placed at the opposite positions by changing regular angle.The results show that amplitude of diffraction wave change along different receiving orientation greatly, if the normal to the vertical direction is set to 0 degree, then the direction of 20° can receive the largest amplitude of diffraction wave. At last, the characteristic curve of diffraction wave is given in this paper.

Design of TOFD receiving filter on DSP builder

Abstract: TOFD (Time of Flight Diffraction), one of the most advanced technologies in the field of NDT (Nondestructive Testing), is widely used in science and industry to evaluate the properties of material, component or system without causing damage. Experiments on TOFD show that signal is greatly disturbed by the noise received by the receiving probe. Based on the performance analysis of four different kinds of IIR filters with the aid of the DSP Builder, modeling and simulation are conducted to test the hardware with real TOFD signals. The design of TOFD receiving filter is finally achieved to suit the signal band and sampling frequency of TOFD.

Modelling of waves propagation on irregular surfaces using ray tracing and GTD approaches: Application to head waves simulation in TOFD inspections for NDT

Abstract: The Time of Flight Diffraction (TOFD) technique is a classical ultrasonic method used in ultrasonic non-destructive evaluation, which allows a precise positioning and a quantitative size evaluation of cracks in the inspected material. Among the typical phenomena arising in the current TOFD inspection, the so-called "head wave" is the first contribution reaching the receiver. The head wave propagation on a planar interface is well known and identified as a critical refraction taking place on the material surface. On irregular surfaces, it has been shown that the head wave results from the melting of surface and bulk waves mechanisms and that surface irregularities are responsible for numerous diffractions of the incident head wave. To simulate such behaviour, a model has been developed using a ray tracing technique based on time of flight minimization (generalized Fermat's principle). It enables the calculation of the ray path and the corresponding time of flight of all waves propagating in the material, including the head wave. To obtain a complete propagation model for these waves (both trajectory and amplitude), the integration of Geometrical Theory of Diffraction (GTD) models is currently performed by coupling them with the ray-based approach discussed above.

Ultrasonic pulse TOFD (time of flight diffraction) collection device

Abstract: The utility model discloses an ultrasonic pulse TOFD (time of flight diffraction) collection device which comprises a device body arranged near a radial artery of a human wrist, a display is arranged on the device body, a power supply circuit, a functional circuit, a storage unit and a microprocessor are arranged in the device body, the microprocessor is connected with an ultrasonic TOFD probe, a micro-pressure sensor and a linear micro-motor through the functional circuit, and the micro-pressure sensor, the linear micro-motor and the ultrasonic TOFD probe are connected The ultrasonic TOFD probe is used for simulating a traditional Chinese medical method and collecting pulse, and all devices are integrated in a smart watch Compared with the prior art, the ultrasonic pulse TOFD collection device is simpler, small, more suitable for portable measurement and lower in cost

Portable time of flight diffraction weld ultrasonic-detection scanner

Abstract: The utility model discloses a portable TOFD (time of flight diffraction) weld ultrasonic-detection scanner, which comprises an integral sliding main support rod, a filter, a junction box, handles, digital encoders, magnetic wheel sets and two sets of corresponding TOFD probe systems. The scanner is characterized in that the sliding main support rod is a long rod with a sliding chute in the middle. According to the scanner, transverse magnetic wheel gaps of the scanner are reduced, and a split design is replaced by an integral design, so that the scanner is suitable for the detection of small-pipe diameter welds; circumferential traveling deviation is avoided; the upward-downward displacement distances of probe brackets are prolonged; the length directions of the bottoms of wedge blocks are shortened, so that good contact surfaces of inner and outer arcs of bends of probes are ensured; the portable TOFD weld ultrasonic-detection scanner can be used for stably detecting welds of bent pipes and welds of straight pipes with diameters of greater than 215mm without swinging.

Supersonic flaw detection method of weld joint

Abstract: A supersonic flaw detection method of a weld joint is characterized in that another two detection channels are arranged on a TOFD detector, creep wave probe scanning of the upper portion of the weld joint and transverse wave probe scanning of the lower portion of the weld joint are carried out while TOFD scanning in order to simultaneously carry out three detections. The respective advantages of UT detection and the TOFD detection are fully utilized, and the whole weld joint can be all-directionally detected through one time scanning. The method has the advantages of high detection efficiency and high accuracy.

Bottom crack measurement by using AATT with ultrasonic phased array

Abstract: This paper proposes an effective method of using ultrasonic phased array to measure bottom cracks from single-sided-unilateral The heights of artificial cracks in different thickness blocks are measured by the Absolute Arrival Time Technique(AATT) with ultrasonic phased array in testing simulation and experiment The height of natural crack in a weld is also measured by AATT A comparative analysis of the experimental results and the conventional TOFD measurement results is conducted, and the analysis results show that the height of bottom crack can be measured quantitatively by AATT from one side and this measurement technique can achieve the same accuracy as TOFD measurement

Special flexible track for TOFD (time of flight diffraction) ultrasonic testing

Abstract: The utility model provides a special flexible track for TOFD (time of flight diffraction) ultrasonic testing The special flexible track is connected with a scanning mechanism by a connecting mechanism in a rigid mode, and comprises a drive mechanism, a lock mechanism, a tensioning mechanism, a crawling trolley, a movable chain and a connecting mechanism, wherein the crawling trolley is fixed on a pipeline; a vertical rod and the crawling trolley are fixed perpendicularly; the tensioning mechanism, the lock mechanism and the drive mechanism are fixed on the vertical rod; the tensioning mechanism comprises an adjusting screw, a compression spring and an adjusting nut; the lock mechanism comprises a gear engagement mechanism and an engaged gear; the drive mechanism comprises a rocking handle, a chain gear, a turbine screw and a turbine gear The scanning with high peripheral walking precision, stable running, balanced pressure and favorable probe coupling for the TOFD scanning mechanism is realized; moreover, the mechanism is applicable to TOFD scanning requirements for pipelines with different diameters by increasing and reducing chain buckles; the special flexible track is portable in installation, is high in detection speed, and guarantees the continuity, stability, clearness and reliability of TOFD scanned images

Method for monitoring intermittent interlayer expansion of steel plate through TOFD

Abstract: The invention discloses a method for monitoring the intermittent interlayer expansion of a steel plate through TOFD. The method comprises the following steps: determining that the mechanical properties of a steel plate used for making a column satisfy requirements; welding the internal and external surfaces of a wing plate having intermittent interlayer defects to supporting legs of guide rails, setting the quantity of the guide rails according to the size of the area of the intermittent interlayer defects, permanently numbering small grids as grid 1, grid 2..., and adjusting apparatus parameters; examining the steel plate in each of the small grids, and measuring the highest amplitude and the length dimension of the intermittent interlayer defect of each of the small grids; and monitoring the steel plate in each of the small grids after furnace power-off, and comparing the examination result of the intermittent interlayer defect in each of the small grids with a previous examination result. The method monitors the expansion of the intermittent interlayer defects in the steel plate by utilizing a TOFD technology, and accurately compares the highest amplitude and the length dimension of a same defect in each time examination by means of the special guide rails, so the expansion of like defects can be effectively monitored.

FEM Model-Based Investigation of Ultrasonic TOFD for Notch Inspection

Abstract: A two-dimensional numerical model based on the finite element method was built to simulate the wave propagation phenomena that occur during the ultrasonic time of flight diffraction (TOFD) process. First, longitudinal-wave TOFD was simulated, and the numerical results agreed well with the theoretical results. Shear-wave TOFD was also investigated because shear waves have higher intensity and resolution. The shear wave propagation was studied using three models with different boundary conditions, and the tip-diffracted shear-tolongitudinal wave was extracted from the A-scan signal difference between the cracked and non-cracked specimens. This signal showed very good agreement between the geometrical and numerical arrival times. The results of this study not only provide better understanding of the diffraction phenomena in TOFD, but also prove the potential of shear-wave TOFD for practical application.

Defect detection of TOFD D scanning image based on parabola fitting

Abstract: A new method was introduced to accurately detect the defects of time of flight diffraction(TOFD) D scanning image.First,the clutter suppression algorithm based on energy distribution was used to remove direct wave and reflected bottom wave.The background clutter could be removed through algorithms of binarization processing,edge detection,corrosion,clustering and removal of small clusters.Then,a parabola was fitted through the least square method,and ordinate vectors of feature points and fitted points were on the correlation processing.With the matching degree of defects and parabola,the defects could be detected.The results demonstrate that the proposed method was effective and accurate.