Research On Theory And Technology For Non-Destructive Testing Of Submarine Pipeline Based On Pulsed Eddy Current

At present,a lot of submarine pipelines in our country have entered the middle and late stage of service.Because of the early industrial level and material technology,many of the submarine pipelines already in service have appeared more serious corrosion problems,so how to accurately detect the corrosion status of submarine pipeline has become the focus of attention of the major oil companies.Traditional ultrasonic testing and magnetic flux leakage testing need to be attached to the pipeline,not only affect the production and it is easy to appear the situation that the pipe is blocked by pipeline pig.Compared with traditional detection methods,pulsed eddy current testing technology can be used for non-contact measurement outside the pipeline and has a very broad market prospect.The research of this field is earlier in foreign countries,but the domestic research is still in the initial stage,so it is necessary to study the submarine pipeline pulse eddy current testing.In this paper,we first reviewed the relevant literature at home and abroad,and the theoretical development and research results of pulsed eddy current testing at home and abroad are summarized,at the same time introduces the pulsed eddy current testing products can be used for ferromagnetic materials at home and abroad,introduces the hardware structure and the system index of the relevant products,and gives the test cases of the related products.Secondly introduces the basic principle of pulsed eddy current testing and theoretical basis,according to the Maxwell equations,the skin depth ? in the pulsed eddy current testing is derived,analyzes the characteristics and the difficulties of the research on the voltage signal of ferromagnetic pulse eddy current testing,organize the characteristic extracting method in the pulsed eddy current testing,and the characteristics of single logarithm processing,double logarithm processing and differential signal processing are analyzed and compared.Again using ANSYS finite element software established the submarine pipeline numerical simulation entity model of pulsed eddy current testing,and the detected voltage signal is processed according to the previous research,by comparing the effect after processing,to determine the research methods of this article,and on this basis,the submarine pipeline structure of bare pipe,double pipe structure of submarine pipelines and reinforced concrete counterweight submarine pipeline is simulated,mainly study the lift-off height,pipe diameter,reinforced concrete weight coating and defect size for the influence law of voltage signal.Finally on the basis of the above theoretical derivation and numerical simulation research,developed a set of pulsed eddy current testing system for submarine pipeline,during the development of the prototype,the key technologies such as high current excitation and weak signal processing and data acquisition in the pulsed eddy current testing system are overcome,in the end of this paper,the principle of the prototype is used to detect the pipeline with different wall thickness.Through the above research,it has played a certain role in promoting the development of pulsed eddy current testing technology.