Development of ultrasonic tomographic instrumentation system monitoring flaws on pipeline

Online inspection and in situ monitoring for natural gas transmission and distribution pipeline is significant to prevent any fatal incident and to maintain pipe integrity. Most inspection technique conducted in industry is for the localized flaws detection. It is important to have an inspection system that is capable of producing an overall image of pipe profile (circumferentially) which can show the actual location of the flaws. Therefore, an ultrasonic tomographic instrumentation system was designed and fabricated for this study to monitor the existence of flaws circumferentially on pipeline. It consists of an ultrasonic sensing system, a data acquisition system and an image reconstruction system (software development). There were twenty-eight ultrasonic sensors arranged on a sensing ring that surrounded a carbon steel pipe NPS 8 (219 mm external diameter). The sensors were contactless to the pipe at a distance of 50 mm. Several testings were conducted to identify the ultrasonic beam pattern, the uniformity of ultrasonic beam intensity and the image grid covered by each sensor. A calibration test on distance measurement was conducted based on 40 mm to 60 mm range of distance, and the result showed ± 0.3 mm maximum error with the average accuracy of 99.82%. Three experiments on flaws detection around the pipe were carried out, which were the external flaws, internal flaws and a combination of external and internal flaws. The depth of flaws was ranging from 0.4 mm to 3.3 mm. From the output data, a tomogram image of the circumference pipe profile with flaws existence was reconstructed using linear back projection algorithm and direct method. The computer programming on image reconstruction was performed using MATLAB software. In brief, the developed ultrasonic tomography system was capable in detecting the flaws on pipeline, and visualizing the actual location of the flaws

Hardware development of reflection mode ultrasonic tomography system for monitoring flaws on pipeline

The pipeline inspection is a key requirement to maintain structural health and pipeline integrity for oil and gas transportation over countries. Pipe failure is a critical problem that needs to be endured within the operational work. The defects or flaws existence on pipeline surface is one of the most leading factors to pipe failures. A new approach of non-destructive technique is implemented to monitor flaws on pipeline by using reflection-mode ultrasonic tomography system. This paper details on the hardware development of ultrasonic tomography system based on reflection mode detection. The system consists of ultrasonic transceiver sensors mounted circularly and contactless to the pipe surface. The modeling work described the ultrasonic ring configuration, ultrasonic signal behavior, sensors arrangement and image grid estimation. The developed instrumentation system is used to detect external and internal flaws on pipe surface. The results show that the reflection-mode ultrasonic tomography is capable to differentiate flaws detected based on the calculated depth verified from the distance measured and through the reconstructed image

Design and fabrication of ultrasonic tomographic instrumentation system for inspecting flaw on pipeline

Pipeline inspection is a key factor in the pipeline maintenance process to optimize the pipe condition. It is important to detect and to locate the flaw or defect before it grows into a critical size that may fail the pipeline's operation, which could lead to severe damage such as explosion and fatal incident. An accurate and reliable data on flaws or defects are compulsory to assess the pipe condition. Hence, a non-intrusive tool can be used for the pipe inspection, which is an ultrasonic tomography instrumentation system. Modelling and designing the instrumentation has been done thoroughly prior to the fabrication the system. There are 28 of ultrasonic transceiver sensors mounted on the ultrasonic sensing ring, with 50 mm distance to the pipe surface. The image area of ultrasonic signal produced by each sensor is 20 mm. The average accuracy of distance calibration is about 99.82% for a sensing range of 40 to 60 mm from the sensor to the pipe surface. An image of the pipe with flaws existence is reconstructed based on the data obtained from the experimental work

Development of reverse ultrasonic tomographic instrumentation system for monitoring irregularities on above ground gas pipeline

This paper presents the development of reverse ultrasonic tomographic instrumentation system to monitor irregularities on gas pipeline surface for aboveground pipe inspection in oil and gas industry. It is very crucial to detect irregularities such as crack or corrosion that may lead to pipeline ruptures which will cause fires and explosion. The developed system is based on the reverse tomographic technique as the object to be imaged is located at the outside layer of pipe, with ultrasonic sensors mounted at specific distance from the object. This researchstarted with the modelling of reverse ultrasonic sensing system that consists of ultrasonic ring design configuration, arrangement of sensors and determination of image area of ultrasonic signal for fabrication purposes. Twenty-eight ultrasonic transceiver sensors are plugged in the ultrasonic ring, where the ultrasonic ring is positioned outside the external pipe surface with a fix distance of 50 mm as modelled. The inspection is based on the detection of ultrasonic signal reflected from the surface or objects to the sensors. Based on the output signal obtained in voltage values, the distance of ultrasonic reflected to the sensor is computed. Several experiments have been carried out to evaluate thecapability of the instrumentation system in detecting irregularities on the pipe. There are seven irregularities simulated around the pipe surface. The irregularities are detected based on the output signal and are analysed based on its depth, which is ranging from 0.4 to 3.3 mm. An image of pipe profile with the irregularities existence is then reconstructed. The results indicate that the developed instrumentation system is capable to detect any irregularities a