Research On Digital Ultrasonic Testing System Of High Temperature Tube

As vital equipment or component in petrochemical industry, high temperature tube has been widely used as reforming furnace tube, cracking furnace tube, pipeline tube and aggregation pipe. Suffering from critical service environment, like high temperature (800oC), high pressure (above IMPa), stress, aggressive medium and so on, creep cracks can easily generate nearby the inner wall and grow toward the outer wall, which will finally leads to the fail of tube. It is of vital importance to testing the creep cracks in tube wall. Ultrasonic nondestructive testing (UNDT) has been used in industrial practical production frequently. Nevertheless, UNDT is restricted to paper records at present, which means results can’t reveal more information of materials tested.The design of digital ultrasonic testing system of high temperature tube is proceed in this paper. The improved aspects of hardware:1、 The transmission and reception of ultrasonic signal are achieved by ultrasonic launch and acquisition card, which abandons the flaw detector and recorder, meanwhile fulfill the digitization of ultrasonic testing results.2、 A probe frame is designed for tubes with outer diameter D between110mm≤D≤152mm. The probe frame is designed for ultrasonic pitch and catch technique. The designed probe frame is used to detect creep cracks with length more than2.5mm, and successfully solves the shortage of testing area.3、 The optical rangefinder is introduced into the testing system to record the position signal. The designed aspects of software:the ultrasonic testing program and upper computer operation interface is wrote based on VC6.0to realizes the digitization of ultrasonic testing.Double channel ultrasonic experimental research is taken on HP ethylene cracking tube to verify the feasibility of the system. Experimental results show that the transmitting signals can be successfully received by the receiving probe and waveforms are clear and complete;"amplitude-distance" recording curves are stable and reliable. The digitization of ultrasonic testing is preliminarily accomplished. Due to time reasons, experimental research on creep cracks and creep expansion are left for future study.