声发射技术在锅炉泄漏检测中的应用

针对锅炉所存在的泄漏缺陷,提出了一种声发射逐点监测方法,然后结合声发射信号幅度历程和波形频谱分析法,通过现场检测实例验证了该方法用于锅炉泄漏缺陷声发射检测的可行性与准确性。     

压力容器无损检测--声发射检测技术

声发射技术是20世纪60年代开始,目前逐步成熟的一种无损检测方法,已被广泛应用在压力容器检测和结构的完整性评价方面。文中简要介绍了国内外压力容器声发射检测的发展史和现状。给出了压力容器用钢的声发射特性和压力容器声发射检测方法,综合分析了国内外压力容器声发射检测的标准、仪器和应用进展。最后指出了压力容器声发射检测的发展方向,即在线监测、声发射信号的模式识别和人工神经网络模式识别分析。     

基于声发射技术的压力容器应力腐蚀检测研究

用声发射对某液体推进剂贮罐出现的焊缝应力腐蚀进行了研究.结果表明,声发射技术可以用来对压力容器的应力腐蚀过程进行监控;根据声发射信号强度及其变化可以准确判断设备的运行状况,定量确定压力容器的服役年限.     

现场压力容器检验的声发射源

自1963年Dunegan首次进行压力容器的声发射检验以来.到目前声发射技术在压力容器检验中的应用已超过了30多a(年)。在这30a中.声发射仪从全模拟式到全数字式已经更新了五代以上.声发射技术在北美、欧洲、中国、日本、澳大利亚等许多国家的压力容器检验中得到广泛应用.并制订了许多声发射检验标准.据文献报道.全世界采用声发射技术检验的大型压力容器有数千台.有关压力容器声发射检验的文章也很多。然而.许多文章只报道了在试验室内进行一台压力容器的试验结果.另一些文章报道了进行许多压力容器声发射检验的统计结果.没有给出现场压力容器检验遇到大量声发射源的特性。本文根据笔者对500多台压力容器现场在役和在线检验的数据,给出了现场压力容器检验可能遇到的多种声发射源。这些声发射源包括裂纹、夹渣、未熔合、未焊透等焊接缺陷的开裂和增长、残余应力释放、氧化皮的剥落、结构摩擦、泄漏、风吹、雨滴撞击和电子噪声等。文中时这些声发射源的定位、分布和关联待性分别进行了分析.并列举了大量的实例。1 定位特性1.1 裂纹1.1.1 焊接表面裂纹和体内深埋裂纹的定位控制焊接工艺.在几何尺寸为内径1800mm、筒体长8000mm、壁厚14mm、材质为16MnR的     

声发射缺陷检测技术的应用与发展

本文详细阐述了声发射这一新兴检测技术的原理和发展过程,论述了其在锅炉压力容器方面的应用。指出了声发射技术的发展方向。     

压力容器密封失效泄漏声发射检测

主要通过介绍两台压力容器密封失效泄漏的声发射检测案例,分析了压力容器密封失效泄漏时声发射信号特性。检测结果显示当泄漏介质为液体时,密封失效泄漏信号为幅度较低的连续型信号,中心频率约为10～50 kHz;当泄漏介质为气体时,泄漏信号为幅度较高突发型信号占优的混合型信号,中心频率约为100～400 kHz,此类信号能通过时差定位方法实现定位。检测结果为类似压力容器泄漏声发射检测提供了参考。     

压力容器模拟缺陷的声发射定位

针对核反应堆环境下压力容器的缺陷检测,为避免检测人员长时间接触辐射剂量,采用声发射检测技术,开展了压力容器模拟缺陷定位试验。根据声发射源性质的不同,分别采用时差定位法和衰减定位法,通过试验标定了两种定位方法的重要参数,实现了模拟声发射源的定位,并且通过试验验证了定位结果的准确性。试验结果表明,时差定位法和衰减定位法均适用于定位突发型声发射源,而连续型声发射源可采用衰减定位法进行定位,定位最大误差均不超过传感器间距的10%,定位效果良好。     

压力容器声发射信号人工神经网络模式识别方法的研究

采用人工神经网络模式识别技术对现场压力容器各种声发射源信号特征参数进行了模式识别分析,提出了采用人工神经网络分类方法对压力容器声发射源信号进行定量分析的概念,从而找到了评价声发射源严重程度的方法,设计和培训的人工神经网络可以给出一个多种因素产生的复合声发射源中裂纹扩展、氧化夹渣断裂、残余应力释放和机械摩擦信号所占的百分比,这一结果使声发射技术对压力容器安全状态的无损评价成为可能。     

CO2/MAG焊接技术在锅炉压力容器生产中的应用

讲述了CO2/MAG焊接方法在锅炉压力窗口生产中的应用，推荐的典型焊接工艺，可提高焊接接头冲击韧性；并列举了MAG焊、药芯焊丝CO2气保焊在受压元件中的焊接应用。     

锅炉压力容器焊接质量控制

对影响锅炉压力容器焊接质量的6个环节,即焊接工艺评定与焊接工艺,焊接材料,施焊过程,焊工培训,焊接检验,焊缝返修从理论和实践上进行充分论述,提出了保证焊接质量应采取的工艺措施,对提高锅炉压力容器焊接质量具有指导作用。     

Application of acoustic emission to seeded gear fault detection

Acoustic emission (AE) is gaining ground as a non-destructive technique for health diagnosis on rotating machinery. There are vast opportunities for development of the AE technique on various forms of rotating machinery, including gearboxes. This paper reviews some recent developments in application of AE to gear defect diagnosis. Furthermore, an experimental investigation that examines the effectiveness of AE for gear defect identification is presented. It is concluded that application of the AE technique to seeded gear defect detection is fraught with difficulties. In addition, the viability of the AE technique for gear defect detection from non-rotating components of a machine is called into question.     

锅炉压力容器焊接自动化技术和应用

锅炉、压力容器是我国的重要基础工业之一,是体现我国工业水平的一个重要标志。为了适应我国能源工业的飞快发展,一些锅炉主导企业与国内焊接设备制造专业厂家在解决高容量、高参数锅炉中出现的耐热、高强材料的焊接质量和生产能力的过程中,采取各种方式的合作,走引进消化吸收再创新道路,提升了自身研发能力,逐渐进入了自主创新阶段,并形成了自己的特色。开发制造出一批自动化水平高、质量优异的锅炉、压力容器专用成套设备产品,提供给锅炉、压力容器厂家并实现出口,提升了我国锅炉及压力容器行业的自动化焊接水平,为我国能源高速发展及走向国际市场作出了贡献。     

Application of acoustic emission sensing to slip detection in robot grippers

This paper discusses the application of acoustic emission signal analysis as a sensing tool for the detection of contact and slip related motion between a workpiece and an end effector. Some results from past work in this area are first reviewed. Different modes of slip motion (rotational and translational) are then discussed. The ability to distinguish between these slip modes is important since it enables the robot to assess the gripping stability and recover positional control of the workpiece. Experimental results are presented to demonstrate the sensitivity of the detected acoustic emission signal to these different modes of slip motion. The effects of the gripping force on the detected acoustic emission is also discussed.     

Application of acoustic emission technique for in situ study of plasma anodising

We studied the formation of ceramic layers on the magnesium alloy AM60 by plasma anodising in an alkaline electrolyte of KOH, KF, NaAlO₂ and Na₂HPO₄·12 H₂O in DC galvanostatic mode. During this process, the acoustic emission technique was used to follow the different stages. Analysis of the acoustic emission parameters and of the waveform characteristics during each stage allowed the different physical phenomena occuring to be distinguished. The film formed was rough and contained numerous pores and cracks. It was mainly composed of Mg, O and Al, but also contained all the elements present in the electrolyte bath. These elements were also found in the plasma.     

Use of acoustic emission technique for the early detection of aluminum alloys exfoliation corrosion

Exfoliation corrosion of aluminum alloys is a form of localized corrosion which affects many industries, specially aeronautics. The study of this corrosion mode using only electrochemical techniques is not fully efficient for the detection and control on line of this phenomenon. Therefore, we developed a non-destructive testing technique based on the acoustic emission recordings in order to follow-up this form of corrosion on aluminum alloys. Indeed, recent works have shown the interest of the acoustic emission for the detection, the monitoring and the localization of pitting corrosion on aluminum alloys. This pitting corrosion phenomenon is currently well understood and the experimental methodology acquired during that study is transposed to the study of exfoliation corrosion of aluminum alloys.The present study is conducted on two aluminum alloys: (Al 2024 T3, and Al 7449 T6 and T7). Samples are immersed 4 days in the modified ASTM STP 1134 saline solution. Observations of the structures after tests show that the exfoliation corrosion sensitivity of alloy 7449 T6 is more important than for alloy 7449 T7 which exhibits only the presence of small and non-occluded pits. Very severe exfoliation corrosion was also observed on Al 2024 T3, but after a longer immersion time or in a more acid solution.The recording of the acoustic emission activity shows evident links between this activity and the exfoliation corrosion rate. The analysis of the signal's characteristics reveals a population corresponding to the release of hydrogen bubbles. A few more energetic signals have also been observed. Their source can be either, the cracking resulting from the separation of sheets of metal, or the development and evolution of hydrogen bubbles formed inside blisters during exfoliation corrosion.     

声发射技术在含缺陷汽包管座检测中的应用

声发射技术能够提供缺陷在应力作用下的动态信息,适于评价缺陷对结构的实际有害程度.因此采用声发射技术对某电厂汽包中的超标缺陷进行检测,能够更准确地评价缺陷的活动性及对汽包的危害性,为缺陷的处理提供进一步的依据,确保电站机组安全稳定运行.     

气保焊在压力容器上的应用

针对气保焊(GSAW)在加压气化中Ⅲ类压力容器壳体主焊缝上的应用，进行了多组焊接工艺评定试验；确定了合理的焊接工艺参数；对比分析了气保焊、埋弧焊和气保焊加埋弧焊3种方法不同匹配的焊接接头的力学性能，证明了气保焊完全能满足压力容器的各种性能要求，并在产品上得到推广应用。     

锅炉及压力容器焊接工艺及管理专家系统

针对目前锅炉及压力容器焊接工艺专家系统（WPDMES）中存在的问题，基于锅炉及压力容器行业标准，重新进行了锅炉及压力容器焊接工艺专家系统的设计，并顺应现代管理的要求，增加了成本核算功能。根据系统要求建立了数据库，以获取专家经验及领域知识为目的建立了知识库，依据推理过程的需要建立了推理规则库。该专家系统突破了现有专家系统单一焊接方法的限制，增设了组合焊接方法的工艺设计。与一般的专家系统相比可维护性强，用户在更新知识库时，只需通过专用模块修改知识库，同时提供了方便的在线帮助系统，具有很强的实用性及推广价值。