Design and Validation of an Articulated Sensor Carrier to Improve the Automatic Pipeline Inspection

Abstract

Pipeline inspection gauges (PIGs) carry out automatic pipeline inspection with nondestructive testing (NDT) technologies like ultrasound, magnetic flux leakage, and eddy current. The ultrasonic straight beam allows technicians to determine the wall thickness of the pipeline through the time of flight diffraction (TOFD), providing the pipeline reconstruction and allowing the detection of several defects like dents or corrosion. If the pipeline is of a long distance, then the inspection process is automatic, and the fluid pressure pushes the PIG through the pipeline system. In this case, the PIG velocity and its axial alignment with the pipeline cannot be controlled. The PIG geometry, the pipeline deformations, and the girth welds cause a continuous chattering when the PIG is running, removing the transducers perpendicularity with the inspection points, which means that some echoes cannot be received. To reduce this problem, we propose a novel method to design a sensor carrier that takes into account the angularity and distance effects to acquire the straight beam echoes. The main advantage of our sensor carrier is that it can be used in concave and convex pipeline sections through geometric adjustments, which ensure that it is in contact with the inner pipe wall. Our improvement of the method is the characterization of the misalignment between the internal wall of the pipeline and the transducer. Later, we analyzed the conditions of the automatic pipeline inspection, the existing recommendations in state-of-the-art technology, and the different mechanical scenarios that may occur. For the mechanical design, we developed all the equations and rules. At the signal processing level, we set a fixed gain in the filtering step to obtain the echoes in a defined distance range without saturating the acquisition channels. For the validation, we compared through the mean squared error (MSE) our sensor carrier in a straight pipe section and a pipe elbow of steel versus other sensor carrier configurations. Finally, we present the design parameters for the development of the sensor carrier for different pipeline diameters.

Research Status and Development Trend of Oil and Gas Pipeline Robot

“…In order to improve the flexibility of PIG robot through bending pipes, Ramirez Martinez et al [19], developed a geometrically adjusted PIG robot, which can improve the detection accuracy by carrying ultrasonic sensors through concave and convex pipes. The system reduces the risk of PIG robot being stuck in the pipeline, and has a joint drive system, which can reduce the energy consumption of the system.…”

Implementation and evaluation of an autonomous airborne ultrasound inspection system

“…It may be readily found from practical experience that probe alignment error causes signal attenuation when the transducer face is not parallel to the target surface. As described in [28], such misalignments produce uncertainties in the measurement process, resulting in measurement errors. This experiment is thus designed to measure the alignment constraints of the transducer and quantify their impact on inspection accuracy in the larger context of the UAV deployment.…”

Wireless flow-powered miniature robot capable of traversing tubular structures

“…Another type of device known as pipeline inspection gauges (PIGs) has been used in industry. Distinguished from in-pipe inspection robots with active motion controllability, PIGs are typically pushed passively by flow pressure inside liquid-or gas-filled pipelines (53)(54)(55)(56)(57)(58). Consequently, they are deficient in active motion control to undertake complex inspection tasks, notably those demanding bidirectional navigation; have limited compatibility with straight or quasi-straight pipelines; and present the risk of scraping damage against pipe walls during motion.…”