共查询到19条相似文献,搜索用时 171 毫秒
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用于水冷壁管腐蚀缺陷的低频涡流检测是如今电站锅炉在线监测工作的重点,为了能够对管道内表面缺陷进行有效、快速的检测,有必要对该过程做进一步的研究。本文利用ANSYS软件对其进行仿真计算,分析了激励频率和裂纹缺陷两个因素对检测效果的影响。这些结论为锅炉水冷壁管低频涡流检测传感器缺陷的检测提供了理论指导和方法。 相似文献
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在换热管污垢检测中,多物理场耦合作用下的实验还不具备开展条件,因此,建立准确的超声波传播模型,进行回波频率优选数值模拟具有重要意义。以有限元为基础,基于COMSOL Multiphysics建立了不同换热管特征下3D有限元模型,讨论了其传播特性与换热管特征和回波激励之间变化关系,求解出多层管道特征频率与回波振型。结果表明:不同换热管特征(管材和壁厚)与压力载荷之间具有相似交互关系,采用超声时域反射法检测管道污垢厚度,至少选取5 MHz回波激励,才可抑制伪吉布斯带来的振荡问题,最优检测频率为10 MHz,且壁厚在3 mm~5 mm时,检测效果达到最佳。数值模拟与实验结果一致,对管道沉积污垢的检测误差能控制在±5%以内,为不同管材特征频率选择提供了定量检测依据。 相似文献
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分析了用超声波脉冲回波声速法测量冷轧乳化液质量分数时,声速与温度、质量分数和压力之间的关系,建立了声速模型。按此模型计算出乳化液质量分数为0~11%、温度在20~65℃变化时的超声波传播速度v.还分析了当乳化液中含有铁屑杂质时对质量分数测量结果的影响,并提出如何避免杂质带来的干扰的方法。仿真结果对研制声速法在线检测乳化液浓度具有极其重要的指导意义。 相似文献
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张军 《机械工人(热加工)》2009,(14):65-66
在超声波探伤中,对于管径≤57mm,壁厚〈6mm的管子,由于管径小,曲率大,管壁薄,用检测中厚壁管的超声波探伤方法进行检测是很困难的。因为一般斜探头的前沿距离长(在15mm左右)。用一次波探伤时,主声扫查不到焊缝的根部,用二次波探伤时,因探头发射的声束宽、声束扩散及小径管内弧面的折射和散射影响,造成屏幕上回波游动范围大,反射回波和声程信息杂乱,判定缺陷困难。 相似文献
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管道壁缺陷超声波在役检测的量化分析研究 总被引:4,自引:2,他引:4
介绍了管道壁缺陷超声波在役检测原理和技术性能,指出超声波在役检测技术具有直接测量和量化的特点,特别适用于管道壁腐蚀减薄缺陷和其它减薄缺陷的在役检测,对管道壁厚度的检测精度高。介绍了管道壁缺陷的超声波在役检测方法,给出了四种典型的管道壁缺陷型式,指出建立并完善管道壁缺陷超声波在役检测的量化分析模型,对于提高检测精度具有十分重要的意义。在对四种典型管道壁缺陷型分析的基础上,通过对四次反射回波时间和相对幅值的分析识别,建立了管道壁缺陷超声波在役检测的量化分析模型,并给出了计算框图。最后,对四种典型管道壁缺陷型式进行了模拟试验分析。 相似文献
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锅炉受热面管氧化皮检测历来都是预防锅炉爆管的重要手段,主要介绍了超声波检测技术在某电厂锅炉末级过热器管内壁氧化皮检测中的实际应用,通过将超声波检测结果与内窥镜检查以及显微镜下的测量结果进行比较,进一步验证了该技术的准确性和可靠性。同时,将该技术与传统的射线拍片技术、不锈钢氧化皮堆积测量技术和割管取样测量等方法做了比较,指出超声波检测技术的优势及应用前景,对指导锅炉检修及保障锅炉安全经济运行具有一定的指导作用。 相似文献
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设计超声检测系统,对薄壁铜管的壁厚均匀性进行检测,用分析处理后的检测结果,作为壁厚控制的调整参数.结果表明,采用该系统获得的调整参数,精度达到0.lmm,保证了薄壁铜管壁厚控制的精确性. 相似文献
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Based on electromagnetic flux leakage (EMFL), a nondestructive testing (NDT) technique for the detection of gas pipe wall thickness is presented, and its principle and feasibility is evaluated by means of equivalent magnetic circuit analysis and finite element analysis. An online NDT device adopting this technique is developed, and its structure and working principle are introduced in detail. This device is composed of a detector array with 32 pipe wall thickness sensors that employ a Hall element as the element for sensing the magnetic flux density, and it can be adapted to pipe diameters from Ø400mm to Ø650 mm. On the basis of the experimental investigation for this device, the influences of some factors on thickness measurement, namely the excitation current, excitation coil turns, gap distance, concentrator of the magnetic field, magnetization time, and number of sensors in the detector array, are revealed and the optimal excitation voltage for the sensors of the detector array is selected. The measuring calibration is given to establish the relationship between the pipe wall thickness and the output voltage of the sensors. The results show that the proposed EMFL for measuring the wall thickness of ferromagnetic pipe is feasible, the technical parameters of the sensor are important for improvement of measurement precision and resolution, and the developed device has precision, resolution, and a linear output curve. Carried by the developed gas pipeline inspection robot through a universal joint, this NDT device can move inside the gas pipeline and monitor the state of the pipe wall. 相似文献
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为了实现特种管道在高温、高压、辐射等特殊环境下管壁厚度的非均匀性检测,提出一种基于微分算法的管道壁厚激光超声测量及特征信号处理方法。采用脉冲激光激励和激光干涉探测的激光超声方法,实验测得管道试件的宽频带激光超声信号。采用数字平均算法对宽带激光超声信号进行去噪处理,提高原始激光超声信号的信噪比。采用微分算法对激光超声信号进行特征提取处理,得到表征管壁厚度的激光超声特征信号。根据管道材料声速和激光超声传播时间反演计算得到管道试件的壁厚值,管壁厚度测量值与实际值的误差小于5%。研究表明,基于微分算法的管道壁厚激光超声测量及特征信号处理方法具有良好的信噪比、准确的信号特征量和较高的测量精度,可用于管道壁厚的在线实时检测以及因腐蚀、应力引起的管道壁厚不均匀性检测。 相似文献
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The in-line inspection of pipelines via the use of intelligent PIGs (pipeline inspection gages) that concerns the detection
and sizing of metal loss (e.g., caused by corrosion) is a well-established technology for liquid pipelines as well as gas
pipelines. Magnetic flux leakage and ultrasonic techniques are used for inspection. The application of conventional ultrasonic
techniques is normally restricted to liquid lines because a liquid coupling medium is required. For reliable crack detection,
only the ultrasonic technique has proven suitable. The cracking in pipelines is induced by fatigue crack growth and stress
corrosion cracking in addition to manufacturing-related phenomena. The state of the art of in-line crack inspection is discussed,
especially as regards typical examples of weld inspection. Special emphasis is placed on data evaluation and interpretation.
The text was submitted by the authors in English. 相似文献
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An automatic system for the nondestructive quality control of seamless pipes in mass line production
V. V. Mul’chin R. N. Farshutnyi R. A. Yasaev V. G. Koz’ev O. V. Orlov A. V. Grushko 《Russian Journal of Nondestructive Testing》2010,46(11):854-859
The structural scheme of an automatic system for nondestructive testing of seamless pipes in the technological line of their
production is considered. The integrated use of ultrasonic and eddycurrent inspection methods reduced the number of missed
flaws and overrejected pipes to a minimum. The refined calculation of the scanning step and turn angle of roll-table wheels
is presented. The minimum reliably detectable area of the discrepancy between the wall thickness of a pipe and specified tolerances
is calculated. The obtained calculation formulas make it possible to optimize the scanning step and increase the efficiency
of inspection by 15.0%. 相似文献