The Microwave Nondestructive Testing Techniques Of Pressure Pipeline

Pipeline transportation as one of the five transport industry plays an increasingly important role in the national economy and the modern industrial. However, in case of the pipeline accidents, it will not only cause material damage, but also bring a large number of personal injury. Therefore, maintaining the safe operation of pipelines and preventing the occurrence of pipeline accidents in production are very important to the pipeline industrial production and safety management department. There are many limitations in the pipeline inspection of traditional detection methods. Therefore, reseaching the advanced technology of pipeline non-destructive testing is of great significance to ensure the safety and stable operation of pipeline transportation.Microwave nondestructive testing of pressure piping technology received extensive attention in long-distance rapid detection and non-contact detection because of its unique advantages such as non-direct contact detection, high detection efficiency, fast scanning and imaging.In this paper, a theoretical and experimental research in microwave technology applied to the nondestructive testing of industrial pipe defects was carried out. First, the analysis of the domestic and international non-destructive testing technology of pressure pipeline and microwave detection technology was made. Second, the details of the nature and transmission characteristics of microwave and the action principle of microwave components ware introduced and basic principles of pressure pipe microwave nondestructive testing technology was analyzed. Third, the program of microwave nondestructive testing of pressure piping surface is designed. Further, the testing device was established and the test steps ware setted. Finally, the experiment of microwave nondestructive testing of pressure piping was carried out. The determination method of defects was grasped and the basis data of size assessment was obtained. The theoretical and experimental results show that:1. Microwave nondestructive testing technology could realize non-contact detection of the pipe outer surface. Therefore, this technology can achieve pressure pipeline nondestructive testing in the case of covering the insulation layer. In addition, microwave nondestructive testing technology can achieve fast positioning and determination of the pipe inner surface defects. Therefore, this technology greatly improves the detection efficiency of pipe surface defects.2. The characteristic parameter (Logarithmic amplitude) shows waveform changes under different thickness when detecting the outer surface defects of pipelines under the cover of the non-metallic layer. Therefore, making a contrast detection by selecting a certain frequency band waveguide probe according to the thickness of non-metallic layer outside the pipe could realize non-contact detection of the pipeline outer surface without removal of the non-metallic layer outside the pipe.3. Microwave nondestructive testing could realize pipe inner surface defect detection. Through imposing the microwave signal at corresponding frequency band from the end of the pipeline, the position of defects in the pipeline inner surface can be obtained by the position of reflection coefficient mutation and the value of electrical length has corresponding relationship with pipe scale. On the basis of the defect location, the size of the reflection coefficient will reflect the size of the defect size. More importantly, microwave nondestructive testing technology is able to achieve simultaneous localization and detection of a variety of defects in the inner surface of pipeline. Therefore, the efficiency of detection of surface defects in pipeline is greatly improved.Through the theoretical and experimental research of microwave nondestructive testing new technology, the non-contact detection of pressure pipe outer surface defects and fast positioning and determination of pressure pipe inner surface defects are successfully realized. Microwave nondestructive testing new technology is an efficient, reliable detection technology and has extremely broad application prospects.