Engineering Development Of Nondestructive Testing Of Submarine Pipeline Based On Pulsed Eddy Current

Pulse eddy current detection technology(PECT)is a kind of detection technology that can effectively carry out corrosion detection and evaluation of inner and outer side of steel submarine pipeline.Because of the pulse signal penetrating ability,for the submarine pipeline with insulation layer and/or concrete weight layer,the purpose of corrosion testing can be achieved without peeling off the coating.The prototype of the pulsed eddy current detection model developed in this paper is mainly used for the corrosion detection of submarine pipeline.After the completion of development,the performance of the prototype is verified and the sea test is carried out.In this paper,firsly,the current situation of corrosion damage and detection technology of marine pipe are introduced,and the principle of PECT is introduced.The formation process of eddy current signal is analyzed,and the relationship between voltage and time is obtained.On this basis,the range of useful signal segments is obtained.Secondly,for PECT,the excitation pulse source is an important part of the system.The magnitude of the excitation current and the falling edge of the square wave are directly related to the size of the eddy current.In order to obtain the high power excitation current source,the PA02 power amplifier chip equipped with excitation drive module is used,in order to achieve the required current magnitude and falling edge time for pulse eddy current detection.On the other hand,since the useful feature of the PECT signal is mainly distributed in the later stage,in the order of mV,the signal is weak and the signal-to-noise ratio is very low.Therefore,the detected voltage signal is filtered,denoised and amplified.Then,the method of single logarithmic coordinate system is used to analyze the useful signal segment and extract the useful feature quantity.Next,because the principle prototype is designed for submarine pipeline testing,sealing and compression resistance of the prototype is of vital consideration.After repeated design and verification,the steel model,wall thickness and size of each working module of the prototype is derermined.Finally,it is necessary to carry out performance testing of the pulsed eddy current detection principle prototype designed,including temperature and pressure testing,andtesting of the steel plates and steel pipes in laboratory to verify its feasibility.After the performance test of the prototype,it is also necessary to carry out the sea test,which is wall thickness and defect measurement undersea.The results of the data obtained underwater are compared with those obtained on land,and the developed prototype of pulse eddy current detection is evaluated comprehensively.This paper provides an important basis for the actual detection of submarine pipeline in future projects.