Research On Ultrasonic Array Inner Detection Technology Of Small Caliber Steel Pipe

As an important part of the ship's piping system,small caliber steel pipes continuously transport fuel,lubricating oil,cooling water and other media to ensure the normal operation of the ship.However,due to the fact that most of the transported media is corrosive and the working environment is harsh,small diameter steel pipes are prone to corrosion defects on the inner and outer walls,resulting in ship accidents.Therefore,Therefore,it is of great significance to inspect the small diameter steel pipes in the ship piping system and find the corrosion defects in the small diameter steel pipes in time.Due to the narrow installation space of small caliber steel pipes in ships,it is not possible to detect external pipe defect effectively,and only internal detection can be chosen.The existing pipeline inspection equipment is mainly aimed at medium and large diameter pipelines.Due to the restriction of the pipe diameter,it cannot meet the detection requirements of small diameter steel pipes.Therefore,in view of the above problems,the paper conduct the research on the internal detection technology of the detect small caliber steel pipes by ultrasonic array.Processed and tested the ultrasonic sensor array with spherical structure after it has been designed,which can have good passing ability in straight pipe and bent pipe environments;The transmitting circuit and receiving circuit of the ultrasonic sensor array are designed to achieve sensor array excitation and echo signal reception and processing;Design a small caliber steel pipe ultrasonic testing software system,which can real-time image of steel pipe defects based on the data obtained by the sensor array.The main research work of the thesis is as follows:(1)On the basis of explaining the background and purpose of the subject,analyze the internal inspection methods and technical status of pipeline defects at home and abroad.According to the working environment and pipeline defect characteristics of small and medium-sized steel pipes in ships,propose the way of the overall scheme of ultrasonic array inspection and imaging system for object defects.(2)According to the requirements of detecting defects,design the geometric structure and working parameters of the ultrasonic sensor;According to the requirements that through the steel pipe at one time when pipeline defect detection,design the structure and layout scheme of the sensor array and analyze the sound field.Under the condition of meeting the defect test requirements,the ultrasonic sensor uses a center operating frequency of 5MHz,the number of sensors is 16,and is placed on a spherical bracket in two columns.By exciting 8 sensors at the same time twice,the solution is realized.When the test ball passes through the steel pipe at one time,it can effectively detect the cross section of the steel pipe.(3)Designed an ultrasonic array transmission circuit capable of generating positive and negative square wave pulses,combined with the characteristics of ultrasonic echo signals and detection accuracy requirements.Then designed a limiter circuit,echo signal amplifier circuit,filter circuit,interface circuit and envelope extraction circuit.And the trial production and test of the circuit are carried out,verify the circuit performance meets the requirements.(4)Designed a small caliber steel pipe ultrasonic internal inspection software system,which mainly includes data acquisition and transmission interface program,feature parameter extraction program,defect visualization program,and interface program of parameter and information,which achieve the function of small caliber ultrasound in the internal inspection,the detection parameter setting,waveform real-time display,data storage,defect quantification and defect visualization.(5)Assembled and debugged the ultrasonic internal testing platform for small caliber steel pipes,and tested small caliber steel pipe samples with standard defects in the laboratory.The test results show that the designed small-diameter steel pipe ultrasonic array internal detection system can accurately detect corrosion defects with 5-10% change in steel pipe wall thickness,and can accurately display the axial position of the defects in the pipeline.