Current state of safety testing of main pipelines

The paper briefly describes the history of quality testing of buried main pipelines. The pioneering research into the development of magnetic techniques for detection of flaws caused by corrosion in pipelines has been conducted at the Institute of Metal Physics of the Ural Division of Russian Academy of Sciences. The fairly high accuracy of measured parameters of detected flaws is confirmed. The topical problems concerning pipeline testing are formulated. Deceased.     

海底石油管道超声检测双向伞式变径技术

我国三种海底石油管道内径分别为Φ195mm、Φ247mm、Φ297mm,超声检测是管道壁厚变薄等缺陷的主要检测方法.为使超声检测装置能够适应三种管道的检测以节省成本,详细分析了适用于三种石油管道的超声探头排布方案;提出并论述了采用双向伞式机构实现超声探头保持架变径的原理,最后介绍了双向伞式变径装置结构设计的关键部分-铰链的结构设计.     

False echo signals during ultrasonic testing of a steam generator

One important special case, namely, the ultrasonic testing of the welded joint of a steam generator was considered. The signal from a flaw is distinguished against a background of signals from technical reflectors.     

Monitoring stressed state of pipelines by magnetic parameters of metal

A method is described for assessing the residual life of pipelines and articles made of structural steels. Dependences between applied stresses and parameters of registered magnetic noises are shown. Criteria are suggested for assessing the in-service destruction of pipeline metal by its magnetic parameters.     

Ultrasonic testing of the stressed state of pipelines with consideration of the temperature factor

The effect of temperature changes on the estimation of biaxial stresses in pipelines by the acoustic method is considered. A method of using the acoustoelastic effect for the estimation of the uniaxial and biaxial stressed states using the changes in the propagation times of longitudinal and shear elastic waves along the normal to the surface of a pipe before and after changes in stress is described. Uniaxial stresses or the difference between biaxial stresses may be estimated by measuring mutually perpendicularly polarized shear wave delays, whose relative difference proportional to the stress value is temperature-independent. The algorithms for estimating the biaxial stresses incorporate parameters that are sensitive to the difference between the temperature dependences of the velocities of longitudinal and shear waves. Some experimental data on the estimation of the error of the method that were obtained at variable temperatures and the results of taking the temperature factor into account in the algorithms for estimating the stresses by the ultrasonic method are given.     

On the possibility of evaluating the stressed state of pipelines using a magnetic method

It is shown that the monitoring of the stressed state of pipelines with the use of a method based on the evaluation of magnetic properties of a pipe metal allows one to solve completely the problems of improving the reliability of a pipeline system of compressor shops, namely, evaluate the stressed state of pipelines, to detect stress concentration zones, monitor the change of stresses in a construction just during the repair of a pipeline and adjustment of pipeline supports, and optimize the character of the reduction in the stress level.     

The role of a stressed state in the formation of stress-corrosion flaws in pipelines

In recent years, as a result of performance of intensive in-tube flaw detection, the integrity and reliable operation of trunk pipelines have been achieved. However, because of an unpredictable development of such tube flaws as stress corrosion, the probability of occurrence of emergencies in pipelines substantially increases. An analysis of the stressed state in pipelines exposed to their main load—the operating pressure—and various types of additional forces is presented. As a result, it is shown that the obtained direction, value, and location of the effective maximum stresses in the tube wall fully correspond to the pattern of statistical formation of stress-corrosion flaws in pipelines. It can be concluded from the data of this study that the standardized tube-strength margin is insufficient; during tube operation, this circumstance may lead to the formation of stresses at the level of the metal yield stress and initiation and growth of stress-corrosion cracks.     

An acoustic method for diagnostics of the state of underground pipelines: New possibilities

The problem of the prevention of emergency situations on pipelines that are caused by leaks of a transferred product, unauthorized insertions, and installation of subversive munitions is considered. The approach to the detection of these threats with the use of an active method for acoustic diagnostics of the state of an underground pipeline is proposed.     

Diagnostics of corrosive state of main gas pipelines with module probe technology

A new method of measuring the corrosion rate of pipelines based on integration of the principle of polarization resistance into the module probe technology is developed for diagnostics of the corrosive state of pipelines. The experimental setup and the method for measuring the corrosion rate of metal objects in soil are developed. The efficiency of the setup and the possibility of recording the corrosion rate under the condition of long preliminary polarization are demonstrated. The results are of interest for development of new variants of diagnostics of the corrosive state of underground metal objects, technical diagnostics, and studies of physicomechanical characteristics of materials.     

超声车削弯曲振动系统的试验研究

设计并制造了三振型弯曲刀杆,计算出其固有频率为20．440kHz。空载下,用自行研制的超声车削弯曲振动装置进行了试验研究。得出刀具在切削速度方向的振幅符合其位移Catx=asinwt,呈正弦曲线,刀尖的振幅最大可达到18．1751μm,最小为10．3996μm,均能满足超声振动车削要求。     

Non-destructive ultrasonic velocimetry for central region velocity fields in turbulent Rayleigh-Bénard convection of mercury

A non-destructive method of measuring flow field of opaque fluids is presented for turbulent convection of liquid metal mercury. Two important properties of the turbulent state, namely 2D velocity profiles and energy spectrum, are successfully measured for Rayleigh-Bénard convection of mercury by using ultrasonic Doppler velocimetry. A few key techniques for the method are also explained.     

Estimating the technical state and safe operational life of pipelines from the results of in-tube nondestructive testing

The testing technique for examining the state and safe operational life of pipelines containing corrosion and stress-corrosion flaws is considered. This technique is currently used to examine the state of pipelines of OAO Gazprom. This technique is based on the processing and analysis of the database on the in-tube inspection of gas pipelines. The results of analysis provide estimation of safe operational lifetimes.     

高温再热蒸汽管道水压堵阀阀体裂纹的补焊

分析了高温再热管道水压堵阀阀体表面裂纹原因,制定了裂纹消除和焊接工艺措施。根据缺陷深度,采用镍基材料低温冷补焊和同质热补焊的两种补焊工艺方法,收到良好效果。     

Modal disturbance investigation of rod-shaped ultrasonic motor using bending vibrations

Modal disturbance of a rod-shaped ultrasonic motor using bending vibrations can cause problems such as low motor efficiency, instability, and poor control. In this paper, a dynamic analysis model of a stator is created on the basis of the finite element method (FEM) and Hamilton principle. The modal frequency sensitivities of the stator to the structure parameters are investigated by modal analysis. Accordingly, the structure parameters of the stator are modified to separate working modes from disturbance modes. A rod-shaped ultrasonic motor stator is fabricated, and the experimental results of its amplitude frequency response characteristics show that the purpose of modal separation is achieved. The frequency separation between working modes and disturbance modes is more than 2 kHz. The validity of the method is verified. __________ Translated from Piezoelectrics & Acoustooptics, 2008, 30(6) [译自: 压电与声光]     

Effect of operation on the stressed state of process pipelines in a pressure blower’s piping

The possibility of assessing parameters of a stressed state from changes in magnetic properties is considered. Such an option would allow determining the sign and magnitude of the effective stresses. Generalized indicators of the stress state of a pipe’s cross section may include data on maximum, minimum, and average “pointlike” stress in the investigated cross section, the amplitudes of extreme values, and the average stresses in the segments of the investigated cross section. It is shown that application of such generalized characteristics of a pipeline’s stress state allows one to sequentially change the scale (selection) of the evaluated segment and compare technological-equipment units through the use of the advantages of the local testing of stresses in combination with averaged parameters of a pipeline’s segment that has a respective scale.     

Experimental investigation on sliding and fretting wear of steam generator tube materials

In nuclear power steam generators, high flow rates can induce vibration of the tubes resulting in fretting wear damage due to contacts between the tubes and their supports. In this paper, the sliding and fretting wear tests were performed using Inconel 600HTMA and 690TT against STS 304, which are the steam generator tube materials. The sliding wear tests with a pin-on-disk type tribometer were carried out under various applied loads and sliding speeds at air environment. The fretting wear tests were carried out under various vibrating amplitudes and applied normal loads.

The result of sliding and fretting wear tests show that the heat-treated Inconel 690TT has better wear resistance than Inconel 600HTMA in air. The fretting wear regimes were plotted using the test results and the wear coefficient was calculated also. From the results, it was observed that the wear and tear by stick-slip has very strong effect on the fretting wear behavior.     

新型超声变幅杆结构设计

针对旋转超声加工回转精度和超声能量传递两方面的要求 ,对变幅杆的联接结构进行研究 ,首次提出并实现了两面定位的联接结构 ,实践证明切实可行     

基于状态反馈与PID相结合的主汽温控制方法研究

针对火电厂主汽温系统的大滞后，大惯性以及动态特性随工况变化的不确定性等特性，本文运用了基于状态反馈与串级PID控制相结合的控制方案．并采用“ITAE性能准则”来进行状态反馈极点配置，同时文中给出了不同阶次惯性环节对应的最佳反馈系数，仿真结果表明，主汽温的动态特性得到明显改善。     

结构参数对超声波流量计水流特性影响的研究

超声波流量计应用于小管径时,在基表内部加装反射装置,延长声程,提高测量精度。反射装置对超声波流量计基表内水流特性影响较大,为了优化表内水流特性,本文针对U型反射的特点提出两种改进措施:反射柱上部削平部分和在此基础上加装导流片。利用SST K-ω模型,对3种基表内水流特性进行数值模拟,分析3种基表内流场分布、声道流速稳定性和压力损失。结果表明,反射柱上部削平部分没有改善流场分布,而在此基础上加装导流片流场明显得到改善,同时两者均增加了声道流速稳定性和减小了压力损失,但后者效果更为显著。