Conceptual design of ultrasonic tomographic instrumentation system for monitoring flaw in pipeline coating

Abstract

This study describes the conceptual design of ultrasonic tomographic instrumentation system for monitoring flaw in pipeline coating. In oil and gas industry, an ultrasonic inspection is the common method used to inspect pipeline integrity due to flaw existence such as corrosion, pitting, holiday, pinhole and others. The ultrasonic tomography system is used in this project to monitor flaws circumferentially on pipeline coating with contactless measurement of distance from sensors which is based on thickness changing in coating. The design of the ultrasonic tomography system consists of ultrasonic sensing system, data acquisition and image reconstruction system. Experimental test for lab scale is performed by using 2 inch pipe. The transceiver sensors of 40 kHz are mounted around the pipe with a distance of 2 cm from sensors to the pipe surface. Reflection mode is used as the ultrasonic sensing mode for the ultrasonic signal as it propagated through air medium to the pipe coating. The data collected are based on ultrasonic signal amplitude and time of flight measured by ultrasonic transceiver sensor. Based on the time travelled by the ultrasonic signal from the sensor to the pipe coating, the distance can be determined using Time of Flight (ToF) method. The thickness changing in pipe coating indicates the existence of flaws (internal or external). From the acquired output data, a tomographic image of pipe coating thickness is reconstructed. In the image reconstruction system, the image coating will be reconstructed using MATLAB software based on suitable algorithm.