Acoustic Emission Testing Of Pipeline Corrosion

Pipe corrosion includes the environmental corrosion of the outer wall as a result of protection layer destruction, corrosion of internal wall because of conveying high temperature, high pressure and high corrosive medium. Pipeline in the manufacturing, processing, welding installation processes will produce internal injury, and in the effect of alternating stress, corrosive media, temperature and other factors these internal injury will produce the crack initiation and continue to expand, which eventually leads to an explosion or even perforation leaks, and results in the huge economic losses and serious casualties accident, therefore the detection of pipeline corrosion damage is particularly important.Commonly used non-destructive testing methods of the pipeline wall include ultrasound, magnetic flux leakage, and eddy current, etc. which in a certain extent achieve the goal of detecting damages of the pipeline body. However, the above methods demand highly for the workpiece to be detected, and require a point-by-point scanning, so heavy workload and high cost of detection are needed, but low efficiency is gained, Therefore they can not be effectively applied to tens of thousands of kilometers of pipeline inspection. There are some characteristics of acoustic emission technology, such as high sensitivity, real-time forecasting, simple, low-cost testing and the overall long-distance monitoring and so on.Therefore this paper aims to study the feasibility about the acoustic emission detection of pipeline corrosion; the main research work includes the following sections:(1) Acoustic emission testing of corrosion immersion for Q235 steel: study characteristics of the acoustic emission signal during the process of metal corrosion, and prove that acoustic emission technology can monitor the occurrence and development of the dynamic process of change.(2) Acoustic emission research of the emergence and the breakdown of single bubble: the process of corrosion often occur as a result of hydrogen evolution reaction, which causes the phenomenon of acoustic emission indirectly reflecting the occurrence of corrosion, and these belong to the phenomenon of secondary corrosion, By monitoring the emergence and the breakdown of a single bubble this paper studied the bubble-type acoustic emission characteristic of corrosion.(3) Acoustic emission testing of industrial pipeline: get the audio feature as well as the characteristics of flow noise siganal of different diametral pipes; receive signal attenuation characteristics of different frequency sensors in the pipeline inspection process; research the impact on the signal position at the department adjustable pipe. (4) Acoustic emission monitoring of pipeline corrosion: simulate the pipeline corrosion test and get acoustic emission signals in the corrosion process; take use of modal acoustic emission technology to analyze propagation characteristics of acoustic emission signals of thin-walled tube and identify the different modal characteristics of the process of pitting corrosion.