№ 4(66) - Deceber 2014

Main Feature: UT Defect Sizing

UT Defect Sizing

G. Nardoni, P. Nardoni, D. Nardoni, M. Feroldi
Zebra and Rainbow Example of Image Quality Standard in TOFD and Phased Array Technique

Image quality is a fundamental parameter to evaluate the correct setup of the equipment referred to the calibration test. In TOFD technique the grey level, as contrast between positive and negative phase, is the main parameter for detection and sizing of defects. Three quality classes have been proposed to graduate the grey level. In addition tips resolution is also expressed as a quality parameter. The first class has zebra as an example of grey contrast. In Phased Array technique, image quality of the reference indication is characterized by a spectrum of colours. This image represents an echo dynamic curve of the reference reflector through which the size of findings is estimated. The first class has rainbow as an example of image standard. The paper presents with different examples the need to establish a standard quality of an image, in particular in the evaluation of the procedure demonstration. This will avoid the rejection of TOFD and Phased Array maps at the final stage of the constructions as it has happened also recently, causing delay and heavy economic consequences.

V. V. Mosyagin, A. A. Markov
Evaluation of the defect real size in products with bilateral access

Evaluation of real defects sizes in tested objects is necessary in order to plan the repair work and to count residual resource. For products with bilateral access a new technique of real defect size evaluation has been developed. The technique is based on an amplitude shadow method of testing. Several independent pairs of transducers are used to avoid ambiguity of measurements; the pairs of transducers provide entrance of ultrasonic waves at different angles. A three-dimensional image of a defect can be achieved with layer-by-layer scanning of a defective section. Modelling of an acoustic tract (approximations of beam geometry) with the use of a specially developed program has been carried out for different models of railhead defects. Modelling of different situations together with experimental researches has made it possible to optimize main parameters influencing on defect sizing accuracy. Selected sizes of transmitting and receiving transducers, optimal operating threshold, and specially developed technique for setting the testing sensitivity were realized in a mockup of a pulsed ultrasonic flaw detector. For practical realization of this approach the new way of acoustic contact providing has been offered and implemented on real objects with poor surfaces for entry/receipt of ultrasound waves. Experimental researches carried out on real defects and models of defects (more than 50 defective sections of railhead) with the mockup have shown satisfactory accuracy and repetition of measurements. The considered approach has restrictions; nevertheless the operation experience shows its practical suitability and satisfactory accuracy in many practical situations. The approach for real defect size evaluation offered in the article can be applied to any objects with bilateral access.

D. S. Lozhkova, M. A. Dalin
Reliability Evaluation of Titanium Alloys Automated Ultrasonic Inspection Using Mathematical Modeling

Problems of titanium alloys disks automated ultrasonic testing reliability evaluation were observed. Foreign approaches are described:
– collecting of statistic information about defect detection during serial inspection and metallographic analysis of disks’ zones containing echoes which exceeded the rejection level;
– manufacturing of special billet containing lots of synthetic hard alpha inclusions. This billet is tested using all available types of ultrasonic technique with different sensitivities for detection of echoes which exceeded the recording level. Further zones with these echoes are examined with metallographic analysis.
Alternative approach using mathematical modelling data of ultrasonic testing processes is designed at FSUE “VIAM”. First it is necessary to manufacture titanium alloy specimens containing synthetic hard alpha inclusions of known size and orientation. Further these specimens are inspected using ultrasonic testing according to estimated manual. Then obtained ultrasonic testing data are supplemented by modelling data. This addition is important to consider defects of different forms and orientations.
To estimate correctness of collecting data, the comparison of real echoes and modelling echoes is brought in this paper. Real echoes were obtained by testing of titanium alloy specimens set using longitudinal and shear waves and by testing of aluminium alloy specimens set using longitudinal waves. Also comparison with CIVA software is shown. The curves “Defect detection probability versus defect’s size” were plotted with the use of the developed mathematical model. The possibilities of alternative using of the developed mathematical model are shown in conclusion.

A. E. Bazulin, H. Benites, V. V. Pronin, D. S. Tikhonov, O. O. Shnel
Continuous Ultrasonic Thickness Measurement of Main Metal and Welded Joints

The problems of sampling ultrasonic thickness measurement are considered in this article. The application of methodologies and technologies using phased arrays are considered. The principles of application of continuous thickness measurement of pipeline main metal and also measurement of pipeline welded joints bottom surface profile using antenna arrays technology and TOFD (time-of-flight diffraction) scheme are described. The simulations of the inspection scheme basic parameters of the technologies are carried out by the method of ray tubes with application the verified software CIVA. Examples of application and technologies measurement results on test blocks are given in the article. The development perspectives of methods using digital antenna focusing for visualization and measurement of bottom surface profile are described.

Abstracts

T. Yu. Sharapova
Internet News

M. V. Rozina, A. S. Suzhaeva
Abstracts of the Articles Published in Other Sources

NDT World Events

Е. М. Vishemirski
OAO “GASPROM” Organizes Adaptation of Modern Instruments for Main-Gas Pipeline Welded Joints Testing

V. А. Syasko
11th European Conference on Non-Destructive Testing

M. Ya. Grudsky
Дефектоскопия–2014

D. A. Terentev
IV International Research and Practice Conference “Acoustic Emission. Possibilities of the Method under Conditions of Modern Risk-Based Approach to Safety Assurance of Industrial and Socially Significant Facilities”. IV School-Seminar “Assessment and Management of Industrial Risks in Industrial Safety”

V. G. Shipsha, A. N. Reger.
Products of Composite and Inhomogeneous Materials. Methods and Instruments for Nondestructive Quality Testing

2nd Annual Photo Contest. “Non-Destructive Testing 2014: Day by Day”

Interview

A. Kh. Vopilkin
“ECHO+” – Looking Through the Years

Acoustic Inspection

N. Amir
Non-Invasive Inspection of Heat Exchanger Tubes

Two well-known methods for inspection of tubes and pipes are Acoustic Pulse Reflectometry (APR) and Guided Waves (GW). Both are based on probing the tubes/pipes using long range acoustic waves, either through the air in the tubes (APR) or the tube walls (GW). Both methods share the advantage of being non-traversing, enabling very short inspection times, on the order of 10 seconds per tube. In addition, each method has complementary advantages and disadvantages. APR for example can detect blockages and very small pinholes but is insensitive to Outer Diameter (OD) defects. GW, on the other hand, can detect OD faults but cannot easily distinguish pitting from through-holes. As opposed to APR, which has been applied to tube inspection for several years, GW has been used mainly for screening applications in large diameter pipes. In this paper we first present several recent developments in GW, giving an implementation that can fit into tubes as small as 3/4" and capable of detecting, classification and sizing of defects. We term this implementation Ultrasonic Pulse Reflectometry (UPR). We then show how a combined system containing both APR and UPR in a single probe provides a comprehensive solution to tube inspection, enabling very rapid inspection and capable of detecting all typical tube defects.

O. V. Murav’eva, V. A. Strizhak, D. V. Zlobin, S. A. Murashov, A. V. Pryakhin
Technology of Acoustic Waveguide Inspection of Pumping and Compression Pipes

The technology of acoustic testing of pumping and compression pipes with use of torsional waves is described; the technology is based on waveguide effects of a multiple reflection method. Formulas for an acoustic tract when employing the multiple reflection method are offered. The main informative parameters of the method are presented, they are: ratios of reflection from a defect for the 1st and nth reflections; attenuation ratio; torsional wave velocity. Statistical data of rejected pipes distribution based on informative parameters aggregation are given; the data have been obtained during industrial usage of acoustic flaw detector ADNKT at pipes maintenance. Possibilities are shown for defects location of various types in pumping and compression pipes both new and used.

Acoustic Emissionя

T. B. Petersen
AE Analysis of Characteristic Ultrasonic Harmonics in Thick-Walled Metal Objects at Impacts

The phenomenon of stress waves radiation excited at solids collision is used in various applications connected with non-destructive testing. When using the AE technique for registration of acoustic sources, in particular impacts, location and identification of the impact source are usually determined and additionally duration, speed, and risk of the impact are estimated. The article demonstrates advanced capabilities of AE method to retrieve from the digitized signals not only information about the actual impacts, but also parameters and properties of the test object, directly during operation. The calculation method is based on the harmonic analysis of AE signals registered at impacts of solid objects on the surface of the thick-walled object. A diagram explaining the formation of basic frequencies for normal and oblique impacts as well as corresponding harmonics contained in the spectra of the signals is presented. Numerical evaluation of test object material mechanical and acoustic properties obtained by the proposed AE data processing method is given.

R. V. Zhukov, V. M. Davydov, S. D. Riazanov, P. I. Melnikov
Acoustic and Emission Examination at Industrial Safety Expertise in Chemical Industry

The results of acoustic and emission (AE) testing of pressure-operated containers and ball tanks used at ammonia producing in chemical industry are given. AE testing was carried out within the scope of industrial safety expertise. The particular cases are considered, when unallowable defects were detected and then repaired. The containers and tanks were loaded by internal pressure increasing up to a test value. The coordinates of detected AE sources were indicated at the apparatus location scheme and then compared with the results of other testing methods. High performance and effectiveness of the AE method are shown. Industrial safety expertise of ball tanks for ammonia with the use of AE testing had been performed several times during 8 years, so it was possible to observe acoustic activity changing with time. During the following ultrasonic testing a great number of extensive unallowable defects were detected, mainly at locations of AE signals. AE-sources were detected in the ammonia overcooler housing at the pressure, which was much less than the working pressure indicated in the technical passport by the producer; they were confirmed after carrying out visual, dimensional and ultrasound testing. Actual gentle operational conditions promoted trouble-free operation of the overcooler. Substantial increase of AE-sources parameters was observed in desulfurization reactor with increase of the loading pressure; AE-sources were concentrated in the welded joints of the housing. At the locations of critical active III-class AE-sources cracks and metal graphitization were detected by ultrasound and metallographic examinations. The article shows high actuality of the AE method for reliable operation of ammonia synthesis containers under the conditions of ageing equipment fleet and increasing time between repairs.

Magnetic Inspection

M. M. Blaow, B. A. Shaw
Magnetic Barkhausen Noise for Reliable Detection of the Heat Affected Zone in Welded Ship Steel Plate

The applicability of the Barkhausen noise technique to non-destructively determine the heat affected zone (HAZ) in welded steel plates was investigated. Magnetic Barkhausen noise (MBN) measurements were conducted on welded hot-rolled low carbon ship steel plates to determine the MBN behaviour following the exposure to elevated heat in a localized region by welding. The exciting field was applied parallel to the weld bead. The results showed a variation in MBN level along a line that crosses the weld bead. The MBN intensity was higher in the near weld material compared with a lower intensity when the measurement setup was moved away from the weld bead in both sides of the weld. The increased MBN level was attributed to the induced residual tensile stresses as a result of the shrinkage of the hot zone. The variation of MBN along the measurement line was eliminated after the welded plate was shot peened. The decrease in MBN intensity after shot peening was attributed to the induced compressive stresses. The results were explained in terms of different mechanisms of interaction of domain walls with residual tensile and compressive stresses.

Thermal Inspection

V. N. Slavkov, A. P. Davidenko
Determination of the Thermal Radiation Coefficient Using Digital Camera at an Active Thermal Inspection of Metal

Methods and algorithms for processing images obtained by a digital camera were developed. Thermal radiation images of the metallic plates (stainless steel) at high temperatures have established the spatial distribution of the thermal radiation coefficient. MathCAD software and LabVIEW were used to develop the algorithms. An experimental setup has been developed which included the combined method of object temperature measuring: pin, using thermoelectric converters, and remote, with the use of a digital camera. Before setting up the experiment, a measuring part of the apparatus was calibrated, and the functional dependence of the brightness temperature on the red component value of digital camera images was pre-set, using a standard black body. According to the results of digital image processing two-dimensional and one-dimensional graphical representation of the thermal radiation coefficient were built. It is noted that the developed method is universal and allows establishing the spatial distribution of the thermal radiation coefficient for different kinds of metals at different temperatures and wavelengths. As a result, at the procedure of thermal inspection it is possible to significantly improve the accuracy of the results through a proper accounting of the thermal radiation coefficient. In addition, this method has sufficiently high resolution.

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ACS, ASK-ROENTGEN, Constanta, Locus, Newcom-NDT(DURR-NDT), Panatest (Rohmann), Fispribor, Защита от коррозии–2015, Территория NDT, NDT Russia