In-line Inspection Tools Research Articles

Verification of the Theoretical Model for Analyzing Dynamic Behavior of the PIG from Actual Pigging

This paper deals with verification of the theoretical model for dynamic behavior of Pipeline Inspection Gauge (PIG) traveling through high pressure natural gas pipeline. The dynamic behavior of the PIG depends on the differential pressure across its body. This differential pressure is generated by injected gas flow behind the tail of the PIG and expelled gas flow in front of its nose. To analyze the dynamic behavior characteristics such as gas flow in pipeline, and the PIG position and velocity, not only the mathematical models are derived, but also the theoretical models must be certified by actual pigging experiment. But there is not any found results of research on the experimental certification for dynamic behavior of the PIG. The reason is why the fabrication of the PIG as well as, a field application are very difficult. In this research, the effectiveness of the introduced solution using the method of characteristics (MOC) was certified through field application. In-line inspection tool, 30” geometry PIG, was fabricated and actual pigging was carried out at the pipeline segment in Korea Gas Corporation (KOGAS) high pressure system, Incheon LT(LNG Terminal) -Namdong GS(Governor Station) line. Pigging is fulfilled successfully. Comparison of simulation results with experimental results show that the derived mathematical models and the proposed computational schemes are effective for predicting the position and velocity of the PIG with a given operational conditions of pipeline.

Design and implementation of 30„ geometry PIG

This paper introduces the developed geometry PIG (Pipeline Inspection Gauge), one of several ILI (In-Line Inspection) tools, which provide a full picture of the pipeline from only single pass, and has compact size of the electronic device with not only low power consumption but also rapid response of sensors such as calipers, IMU and odometer. This tool is equipped with the several sensor systems. Caliper sensors measure the pipeline internal diameter, ovality and dent size and shape with high accuracy. The IMU (Inertial Measurement Unit) measures the precise trajectory of the PIG during its traverse of the pipeline. The IMU also provide three-dimensional coordination in space from measurement of inertial acceleration and angular rate. Three odometers mounted on the PIG body provide the distance moved along the line and instantaneous velocity during the PIG run. The datum measured by the sensor systems are stored in on-board solid state memory and magnetic tape devices. There is an electromagnetic transmitter at the back end of the tool, the transmitter enables the inspection operators to keep tracking the tool while it travels through the pipeline. An experiment was fulfilled in pull-rig facility and was adopted from Incheon LT (LNG Terminal) to Namdong GS (Governor Station) line, 13 km length.

Machining of simulated defects in pipeline steels: A neutron diffraction study of local stress effects

The most commonly used in-line pipeline inspection tools utilize the magnetic flux leakage (MFL) technique, which is sensitive to the stress state of the pipe wall. Calibration of these MFL tools is often carried out using unstressed pipeline sections containing simulated defects, usually produced by mechanical drilling. There is also strong interest in creating simulated defects in stressed pipe walls, thus simulating corrosion in the field. In this study, neutron diffraction is used to map the local stresses surrounding mechanically and electrochemically drilled holes in a steel plate sample. Holes were drilled in unstressed samples, as well as samples held at a constant 80 MPa uniaxial stress. Mechanical drilling into a stressed sample was found to induce considerable residual stresses around the hole. Conversely, electrochemical drilling did not create a residual stress field in the vicinity of the hole.

Development of small diameter in-line MFL inspection tools: a technical challenge: Laursen, P.; Atherton, D.L.; Proceedings of the 4th (1994) International Offshore and Polar Engineering Conference, Osaka (Japan), 10–15 Apr. 1994. Vol. IV, pp. 425–430. Edited by Y. Ueda, J.F. Dos Santos, I. Langen, Y. Tomita and K. Waagaard. ISOPE (1994) ISBN 1-880653-14-1

Development of small diameter in-line MFL inspection tools: a technical challenge: Laursen, P.; Atherton, D.L.; Proceedings of the 4th (1994) International Offshore and Polar Engineering Conference, Osaka (Japan), 10–15 Apr. 1994. Vol. IV, pp. 425–430. Edited by Y. Ueda, J.F. Dos Santos, I. Langen, Y. Tomita and K. Waagaard. ISOPE (1994) ISBN 1-880653-14-1

Line stresses affect MFL defect indications

Pipeline-defect measurements by high-resolution magnetic flux leakage (MFL) in-line inspection tools are influenced by bending and line-pressure stresses. Tests conducted on a single 36-in. sample with a machined defect indicate that much further research into this phenomenon is needed to reveal methods for correcting for stress effects. The limited, preliminary tests reported in this article were conducted at Queen's University, Kingston, Ontario, and were supported by the Canadian Natural Sciences & Engineering Research Council and by Pipetronix, Toronto.