先进的超声导波无损检测技外文文献翻译、中英文翻译、外文翻译

先进的超声导波无损检测技术

炼油石化工业和其它工业所用的管道在长时间服役后，腐蚀是一个经常被人们关心的问题，尤其是管外（即使是加装了防腐层后管外壁）的腐蚀问题，一旦失效，将给生产和人身带来严重的损害。因此，管道安全运行，首先要适时检测其管壁强度，被腐蚀或有裂纹﹑渗漏等要有预警。

管外防腐层的剥除费用高，不但费时、费工，而且当遇有公路交叉时，管道只有进行大规模挖掘才能进行腐蚀检测。这就引出了具有世界先进水平的较理想的“超声导波技术”，现已由国内开发研究成功。对管壁的这种超声导波检测为上述问题提供了一个非常好的解决方法。在一处安装后，可以沿管道传播若干米，反射的回波便可显示管道的腐蚀或其它特征。

超声导波检测技术利用低频扭曲波或纵波可对管路、管道进行长距离检测，包括对于地下埋管不开挖状态下的长距离检测。超声导波（也称为制导波）的产生机理与薄板中的兰姆波激励机理相类似，也是由于在空间有限的介质内多次往复反射并进一步产生复杂的叠加干涉以及几何弥散形成的。但是对于管道检测，在一般管壁厚度下要产生适当的波型，则需要使用比通常超声波探伤低得多的频率，导波通常使用的频率f＜100KHz，因此导波对单个缺陷的检出灵敏度与通常使用频率在MHz级别的超声检测相比是比较低的，但是导波检测的优点是能传播20~30米长距离而衰减很小，因此可在一个位置固定脉冲回波阵列就可做大范围的检测，特别适合于检测在役管道的内外壁腐蚀以及焊缝的危险性缺陷。低频导波长距离超声检测法用于管道在役状态的快速检测，内外壁腐蚀可一次探测到，也能检出管子断面的平面状缺陷。

超声导波应用的主要波型包括-扭曲波（也简称为扭波）和纵波。扭曲波的特点是能够一边沿管子周向振动，一边沿管子轴向传播，声能受管道内部液体影响较小（在导波检测时，液体在管道中流动是允许的），回波信号能包含管轴方向的缺陷信息，通常能得到清晰的回波信号，信号识别较容易，在应用中需要换能器数量少，重量轻、费用省、因管内液体介质而产生的扩散效应较小，波型转换较少，检测距离较长，对轴向缺陷灵敏度高。

超声导波检测的工作原理：探头阵列发出一束超声能量脉冲，此脉冲充斥整个圆周方向和整个管壁厚度，向远处传播，导波传输过程中遇到缺陷时,缺陷在径向截面上有一定的面积,导波会在缺陷处返回一定比例的反射波,因此可由同一探头阵列检出返回信号-反射波来发现和判断缺陷的大小。管壁厚度中的任何变化，无论内壁或外壁，都会产生反射信号，被探头阵列接收到，因此可以检出管子内外壁由腐蚀或侵蚀引起的金属缺损（缺陷），根据缺陷产生的附加波型转换信号，可以把金属缺损与管子外形特征（如焊缝轮廓等）识别开来。导波的检测灵敏度用管道环状截面上的金属缺损面积的百分比评价（测得的量值为管子断面积的百分比），导波设备和计算机结合生成的图像可供专业人员分析和判断超声导波检测得到的回波信号基本上是脉冲回波型，有轴对称和非轴对称信号两种，检测中以法兰、焊缝回波做基准，根据回波幅度、距离、识别是法兰或管壁横截面缺损率的缺陷评价门限等以及轴对称和非轴对称信号幅度之比可以评价管壁减薄程度，能提供有关反射体位置和近似尺寸的信息，确定管道腐蚀的周向和轴向位置，目前超声导波检测灵敏度可达到截面缺损率3%以上，即一般能检出占管壁截面3~9%以上的缺陷区以及内外壁缺陷。缺陷的检出和定位借助计算机软件程序显示和记录，减少操作判断的依赖性（避免了操作者技能对检测结果的影响），能提供重复性高、可靠的检测结果。应当注意超声导波检测不提供壁厚的直接量值，但对任何管壁深度和环向宽度范围内的金属缺损都较敏感，在一定程度上能测知缺陷的轴向长度，这是因为沿管壁传播的圆周导波会在每一点与环状截面相互作用，对截面的减小比较灵敏。

超声导波与传统超声波检测的最大区别是，前者可在一个测试点对一个大的长距离管道的材质进行100%的检测，而传统的超声波在一个测试点只能对该点进行检测。超声导波的频率范围为5～60kHz，传播速度为3260米／秒，检测时不需要液体进行耦合。它采用机械或气体施加到探头的背面以确保探头与管道表面接触，达到超声波良好的耦合。为了使声波以管道轴芯对称地进行传播，管道环向的超声波探头均匀地间隔排列，如此环向声波沿着管道传播，能使整个管道被振动的声波而“激励”，使其作为波导的媒体而处于“工作”状态中。

超声导波与传统超声波检测的第二个区别是，后者若对壁厚进行测量，只能检测到传感器下管壁的厚度，所以，在检测大范围管线时的速度很慢，而且常常要找

出几个有代表性的特征点进行检测。一旦遇到埋地或绝缘的管道，则束手无策。而使用特制安装在管道上的传感器环进行检测，操作人员利用WAVEMAKER（WPSS）检测系统就可完成单项测试，而且能够对传感器环两侧数十米内的管道进行有效的检测。传感器两侧的有效检测距离是受到多种因素制约的，条件好的情况下，可达几十米，条件不好或有某种覆盖层情况时，只能检测几米。

总之，作为无损检测领域内刚刚兴起的超声导波技术，利用其检测距离长，操作简单和灵敏度高等优势，通过与其相配的检测装置，不但适宜于在役管道的腐蚀检测、新建管道基线检测，而且，对埋地、穿越、架空等管道进行腐蚀情况检测也更具优势。这项技术可用于炼油、化工、石油、天然气输送、电力建设以及战场、密闭系统所涉及的各种工业管道、压力管道，是确保生产安全运行的好帮手。

Advanced NDT ultrasonic guided wave

Oil refining and petrochemical industry and other industrial pipes used after long service, corrosion is a problem often people concerned, especially the outer tube (even after the installation of a coating tube wall) corrosion problems, once spent, will production and cause serious bodily harm. Therefore, the safe operation of pipelines, the first to timely detect the wall strength, corrosion or cracks and other leaks have ﹑ warning.

Tube coating stripping costs high, not only time-consuming, laborious, and when crossing the road in case when the pipeline only large-scale mining in order to detect corrosion. This leads to the world's advanced level than ideal "ultrasonic guided wave technology", has been successfully developed by a domestic research. This Guided Wave wall provides a very good solution to the above problems. After an installation, can spread several meters along the pipeline, the reflected echo can display or other features of pipeline corrosion.

Guided Wave technology uses low-frequency wave or longitudinal wave may be distorted on the line, long-distance pipeline inspection, including the long-range detection of underground pipe without excavation state. The mechanism of ultrasonic guided waves (also known as guided waves) and the thin Lamb waves excited in a similar mechanism, but also due to multiple reflection back and forth in the limited space of the media and further generate complex geometric superposition of interference and dispersion formation. But for pipeline inspection, under normal wall thickness to produce a suitable wave, you need to use much lower than usual ultrasonic flaw detection, the frequency f <100KHz waveguide commonly used, and therefore a single guided wave detection of defects normal sensitivity level of frequency in MHz ultrasound is relatively low in

comparison, but the advantage is capable of detecting guided waves propagation distances of 20 to 30 m and small attenuation, and therefore may be fixed in a pulse-echo array location can be expand the range of detection, particularly suitable for detecting the inner and outer walls of pipeline in service and weld corrosion dangerous defects. The low-frequency wavelengths from the guide pipe ultrasonic inspection method for rapid detection of in-service state, the inner and outer wall corrosion can once detected, can be detected in the pipe cross-section of the planar defects.

The main wave ultrasonic guided wave applications include - distorted wave (also referred to as torsional wave) and longitudinal waves. Distorted wave can be characterized by a circumferential vibration edge tube, a tube axial edge propagation of sound energy that is smaller inner tubing liquid influence (when guided wave detection, the liquid flowing in the pipe is allowed), echo signals can defect information includes the tube axis, typically yield a clear echo signal, signal recognition easier, in applications requiring a small number of transducers, light weight, save cost, the diffusion effect due to the smaller tube and the liquid medium is generated, mode conversion fewer long distance detection, high sensitivity axial defects.

Works Guided Wave: The probe array emits a pulse of ultrasound energy, the pulse flooded the circumferential direction and the entire wall thickness, to the distant spread, when the guided wave transmission encountered defects, defects in radial section there is a certain area, guided wave will return a certain percentage of the reflected wave defects, so by the same array of probes detected return signal - reflected waves to detect and determine the size of the defect. Wall thickness of any change, no matter the inner wall or the outer wall, the reflected signal will have been received by the array probe, it can be detected by the tube

outer wall corrosion or erosion caused by metal defects (defects), additional wave type according to the defects switching signal can be a metal tube defects and shape features (such as weld contour, etc.) to identify open. Guided wave detection sensitivity percentage evaluation defect area metal pipe of annular cross-section (measured as a percentage of the value of the pipe cross-sectional area), waveguide devices and computer-generated images for combining professional analysis and judgment ultrasound guide echo signal wave detection was basically pulse-echo type with axial symmetry and non-axial symmetry signal two types of detection to the flange weld echo as benchmark, according to the echo amplitude, distance, recognition is flange or symmetry axis and the ratio of signal amplitude and non-axisymmetric cross-section of the wall defect rate of defect evaluation threshold, etc. can evaluate the degree of wall thinning, can provide information about the reflector location and approximate size of the information to determine the pipeline corrosion and circumferential the axial position of the current ultrasonic guided wave detection sensitivity can be achieved sectional defect rate of 3% or more, which generally can be detected more than sectional accounts wall 3 to 9% of the defective area and the outer wall defect. The detection and localization of defects by means of a computer software program displays and records, reducing operator dependence is determined (avoids operator skills on the test results), can provide high repeatability and reliable test results. It should be noted Guided Wave does not provide a direct measure of the thickness, but any wall depth and ring are more sensitive to defects within the width of the metal, to a certain extent, sensing the axial length of the defect, it is because circumferential guided waves propagating along the wall in every point of interaction between the annular cross-section of reduced cross-section is more sensitive.

The biggest difference with the traditional ultrasonic guided wave ultrasonic testing is that the former can be a test point on a big long distance pipe material 100% testing, and in a conventional ultrasonic test point can be detected this point. Guided wave ultrasonic frequency range is 5 ~ 60kHz, the propagation velocity of 3260 m / s, without coupling liquid is detected. It uses a mechanical or gas is applied to the back of the probe to ensure that the probe is in contact with the surface of the pipe, the ultrasonic achieve good coupling. To make the sound waves to the pipe axis core symmetrically spread, pipe hoop ultrasonic probe evenly spaced, so ring to acoustic wave propagation along the pipeline, enabling the entire pipeline is vibrating sound waves "incentive" to act as a waveguide the media in the "work" state.

The second difference with the traditional ultrasonic guided wave ultrasonic testing, the latter if the wall thickness is measured only detect the thickness of the sensor under the wall, so the speed in detecting a wide range of pipeline is very slow, and often find a few representative feature point detection. Once encountered buried or insulated pipe, helpless. The use of special sensors installed in the pipe loop is detected, the operator use WAVEMAKER (WPSS) detection system can be completed in a single test, but also to the sensor ring on both sides of the pipeline within tens of meters for effective testing. When both sides of the effective detection distance sensor is subject to many factors, the conditions under good circumstances, up to tens of meters, are poor or have some sort of overlay situation, can only detect a few meters.

In short, as in the field of nondestructive testing nascent ultrasonic guided wave technology, using its long distance detection, simple operation and high sensitivity advantages, through its matching detection means, not only suitable for the corrosion detection of pipeline in

service, the new pipeline baseline testing, Moreover, buried, crossing, overhead and other pipeline corrosion detection is also an advantage. This technology can be used in oil refining, chemical, petroleum, natural gas, electric power construction and industrial piping battlefield, involved in a closed system, pressure pipe is to ensure the safe operation of the production of a good helper.