Oil Pipeline Defect Research Articles

Structural Optimization and Simulation of a Magnetic Leak Detection Device for Streak-like Defects in Oil Pipes

Striped defects are a common type of defects in oil pipelines, divided into horizontal and longitudinal stripes, and it is difficult to accurately quantify the results of conventional pipeline leakage magnetic detection to correspond to the type of defects and their extent. In this paper, a new type of oil pipe non-destructive testing equipment is proposed and designed based on the principle of magnetic leakage detection using three-dimensional finite element simulation, and the magnetic field distribution inside the equipment is simulated using ANSYS finite element analysis software to provide original data reference for the development of the new equipment.

Three-dimensional finite element analysis and research of leakage magnetic field of flake, pit, through-hole defect in petroleum pipelines

Abstract Flake, pit and through-hole defects are the three common types of defects in oil pipelines. In practical testing applications, it is necessary to clarify the magnetic leakage characteristics of different defects and set reasonable detection points to distinguish different types of defects accurately and quantify the degree of each defect precisely. In this paper, the leakage magnetic field of flaky, pitted and through-hole tube wall defect is analyzed. Using three-dimensional finite element simulation, the spatial stereo model of leakage magnetic field is inverted by extracting the data of characteristic nodes. The distribution of the leakage magnetic field in space, for the radial and circumferential components is obtained. On this basis, the effect on the main components of magnetic leakage field at different locations in space is determined, and the best of placing a potential sensor for detecting three kinds of defects in space are derived. This provides a basis for determining sensor locations in magnetic leakage detection devices, inverting defect models from multi-sensor data and accurately quantifying the degree of defects.

Monitoring Corrosion Defects in Oil Pipelines

Monitoring Corrosion Defects in Oil Pipelines

Fast neutron and γ-ray backscatter radiography for the characterization of corrosion-born defects in oil pipelines

In this research, a combined fast-neutron/γ-raybackscatter imaging technique is described. The aim of this work is to understand corrosion defects in pipelines by measuring differences in the scattered radiation flux, generated when different steel thicknesses are irradiated by a neutron and γ-ray focused beam. A californium-252 radiation source is used to produce fast neutron and γ rays, exploiting its spontaneousfission. This mixed radiation field is collimated and directed towards the steel samples. Backscattered neutrons and γ rays aremeasured as a function of the steel thickness using 4 liquid organic scintillation detectors linked to a real-time, pulse-shape discrimination system, which separates and retains the neutron and γ-ray event data. In this paper, we describe how, using asingle radiation source and detection system, it is possible to perform and combine two complementary imaging modalities. This research is validated by an MCNP6 computer simulation study. The backscatter imaging system developed for this research and the experimental results of the measurements carried out using the National Physical Laboratory neutron low-scatter facility are also presented in this paper.

Corrosion Depth Inversion Method Based on the Lift-Off Effect of the Capacitive Imaging (CI) Technique

As a new Non-destructive Evaluation (NDE) technique, capacitive imaging (CI) has been used to detect defects in oil pipelines, composite sucker rods and storage tanks in recent years. When a CI sensor is used to detect corrosion defect on a conducting surface with or without an insulation layer, the depth information of corrosion defect is difficult to acquire due to the non-linearity of the probing field. This paper proposed a corrosion depth inversion method based on the lift-off effect of the CI technique. The proposed depth inversion method, which includes three steps, namely establishing the lift-off curve, obtaining the scan curve and fitting inversion, are introduced and evaluated. In the FE simulations, the error rates of the inversion depths are less than 1.20%. CI experiments were carried out to acquire the depth information of a step shape specimen using the CI experimental system and the proposed corrosion depth inversion method. The results show that the depth inversion method can meet the need of obtaining the actual depth information with the error rates of the inversion depths being less than 10.00%. A CI experiment on a machined and corroded specimen was carried out to further demonstrate the feasibility of the proposed inversion method for corrosion defects with different depths. Both results from FE models and experiments indicate that the proposed method is promising to achieve the quantitative NDE of the Corrosion Under Insulation (CUI).

Evaluation of corrosion defects in oil pipelines based on the approaches of fracture mechanics

We study the development of corrosion defects in an industrial oil pipeline. Defects appearing in the pipeline after 5 and 10 yr of operation are measured by the ultrasonic method. It is shown that, after 10 yr of operation, the pipe wall becomes thinner by 22% (as compared with its initial thickness). To evaluate the defectiveness of state of the pipeline, we use the concepts of J -integral and crack-opening displacement δ. The experimental data on corrosion defects are used to find the values of J-integral.