利用电容变化率实现管道保温层缺陷的自动检测

Automatic Detecting of Pipe Insulating Layer Defects by Capacitance Sensing Technique

对于具有泡沫塑料保温层的钢质管道生产厂家来说,保温层质量的自动检测是一个急待解决的难题。作者提出了一种利用电容变化率实现保温层缺陷自动无损检测的有效方法。本文介绍了该方法的原理和其独特的优点,以及据此方法构成的保温层缺陷检测仪。文中还叙述了作者根据被测管道特点所设计的环状、多探头电容传感器的结构,深入讨论了传感器极板尺寸的设计原则和对测量数据的滤波处理方案等。作者研制成功的样机,在保温输油管道制造现场进行了多次检测,均获得满意的结果。

The pipes with insulating layer are used widely both in oilconveying pipeline and in city heating system.The defects existed in thelayer,such as holes with different depth,incomplement foaming and so on,will result in the decrease of the thermo-insulating efficiency dramatically.Moreover,the conveying pipeline can not be operated normally.Therefore,itis necessary to develop a new instrument for detecting the defects in pipeinsulating layers.The authors presented a novel scheme of detecting the defects by identifyingthe changing rate of capacitance.The remarkable feature of this method is toimmune the influence caused by the variation of environmental humidty andtemperature,which always get the usual capacitance sensing device into trouble.An intelligent instrument based on this principle has been developed bythe authors.Experiments carried out in an insulating oil conveying pipe ma-nufacturing plant have shown that this novel device worked perfectly.In this paper,the construction of ringlike measurement device and the arr-angement of 12 transducers in it are given.The principle of designing thedimension of moving plate and the method of date processing are described indetail as well.