The Study On The Method Of Data Acquisition And Processing For Ultrasonic Testing Of Seabed Pipeline Flaw

Along with the development of our country ocean petroleum natural gas, the seabed piping built increases continuously. In order to guarantee the safety of in-service pipeline, it is necessary to carry on examination periodically so that the problem can be discovered in time and proper measures can be adopted. It elaborates the present developing condition of local and international piping examination technique, besides, it also introduces UT and its examine principle.Aiming at the technical difficulty of data acquisition and processing in the course of piping examination, a new type data acquisition and processing system for twenty-four channel digitalized ultrasonic testing based on ALTERA's advanced FPGA is developed through theoretic calculation of data collecting speed and saving capacity of piping examination. The system adopts high-speed A/D conversion chip. It realizes on-line compression of sampled data while collecting ultrasonic echo signal. Besides, it carries out the buffer of high-speed data saving under the control of FPGA. The project designs stage machine to carry out the control of data collection, applying VHDL language to carry on a description to the hardware electric circuit. Under QuartusⅡ6.0 software environments, the function of the stage machine designed is imitated really. The system physical volume of designing is small, the achievement consume is low, the function is strong, the integration degree is high, laying solid foundation for the off-line analysis of flaw signal data.Moreover, the paper has done much analytical research work for pre-processing of ultrasonic wave signal, mainly including signal de-noising and data compression. According to the characteristics of ultrasonic flaw echo-wave, an algorithm of extremum filtering is constructed to suppress pulse noise on-line,other noise is eliminated off-line using wavelet transform, these noise is considered to be unstable white noise. At last, the data compressing handle method is introduced and the concrete hardware circuit is presented. Experiment verifys that applying the method can reserve characteristic points of echo-signal efficiently, satisfying the practical demand.