• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.404-408
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• 2009

Gas pipelines in bridges, roads and subway construction sections can undergo abrupt stress and vibration changes. To protect human life from any gas leakage accidents induced by the abrupt stress and vibration, the gas pipeline system needs to be continuously monitored. The estimation method of pipeline stress using MEMS wireless tilt sensor has been developed and its validity has been evaluated using a lab test bench.

• Corrosion Science and Technology
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• v.4 no.1
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• pp.1-7
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• 2005

An alternating current (AC) corrosion on buried pipeline has been studied using coupon and ER probe. Coupons and ER probes were applied to the sites from high value of AC voltage to low value based on the survey of AC voltages on buried gas transmission pipeline over the country. Parameters such as AC current density of coupon, AC voltage, cathodic protection potential, soil resistivity and frequency were monitored continually. Corrosion induced by AC was observed even under cathodically protected condition that met cathodic protection criterion (; below -850 mV vs. CSE). Corrosion rate was affected mainly not by AC voltage but by both of frequency and AC current density. An experimental corrosion rate relation could be obtained according to effective AC current density, in which AC corrosion rate increased linearly with effective AC current density, and its slope was 0.619 in coupon method and 0.885 in ER probes.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.470-473
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• 2000

Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Moreover, normal steady state and fault currents become higher as electric networks increase in size and power. Therefore, there has been and still is a growing concern (safety of people marking contact with pipeline, risk of damage to the pipeline coating, the metal and equipment connected to pipeline. especially cathodic protection system) about possible hazards resulting from the influence of high voltage power system on metallic structures(gas pipeline, oil pipeline and water pipeline etc.). Therefore, we analyze the interference problems when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about interference mechanism, AC corrosion, limitation of safety voltage and analysis of indiction voltage.

• Transactions of the Korean hydrogen and new energy society
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• v.27 no.6
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• pp.764-772
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• 2016

This paper presents on the evaluation of numerical analysis model of a ball valve used for a gas pipeline. The ball valve has important role to control the gas flow of the pipeline as well as safety operation to prevent gas explosion at the emergency. For the validation of numerical simulation, the computational domains are introduced three different types: a hexahedron chamber connected to a pipeline outlet without considering the geometry of pressure tubes, a pipeline only considered the geometry of pressure tubes, and a pipeline connected both of the a hexahedron chamber and pressure tubes. The commercial code, SC/Tetra, is introduced to solve the three-dimensional steady-state Reynolds-averaged Navier-Stokes analysis in the present study. The valve flow coefficient and valve loss coefficient with respect to the valve opening rate of 30%, 50%, and 70% are compared with experimental results. Throughout the numerical analysis for the three analysis domains, pressure computed along the pipeline is affected by computational domains. It is noted pressure obtained by the computational model considering both of the a hexahedron chamber and pressure tubes has a relatively good agreement to the experimental data.

• Journal of the Earthquake Engineering Society of Korea
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• v.11 no.6
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• pp.41-52
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• 2007

Earthquake time-history analyses have been carried out for a buried gas pipeline of X65 which is of popular use in Korea. Parameters included are shape of a buried gas pipeline, soil characteristics, single and multiple earthquake input ground motions and burial depths. Predicted response of strain and relative displacement are then compared with allowable strain and displacement capacity calculated by Guidelines for the Seismic Design of Buried Gas Pipelines, KOGAS. Comparative studies show that strains are in general affected by the burial depths together with change of soil conditions. Regarding the relative displacement, while axial relative displacement is not influenced by the burial depths, transverse relative displacement is affected by both burial depths as well as soil conditions. In all, the current study is encouraged to give a useful information for healthy earthquake evaluation of a buried pipeline.

• Journal of the Korean Institute of Gas
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• v.4 no.3 s.11
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• pp.26-32
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• 2000

Because of the continuous growth of energy consumption, and also the tendency to site power lines and pipelines along the same routes, the close proximity of high voltage structures and metallic pipelines has become more and more frequent. Moreover, normal steady state and fault currents become higher as electric networks increase in size and power Therefore, there has been and still is a growing concern(safety of people marking contact with pipeline, risk of damage to the pipeline coating, the metal and equipment connected to pipeline, especially cathodic protection system) about possible hazards resulting from the influence of high voltage power system on metallic structures(gas pipeline, oil pipeline and water pipeline etc.). Therefore, we analyze the interference problems when the gas pipeline is buried with power cable in the same submarine tunnel. This paper present the results of the study about interference mechanism, AC corrosion limitation of safety voltage and analysis of induction voltage.

• Journal of the Korean Institute of Gas
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• v.18 no.2
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• pp.62-68
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• 2014

Composite repair methods besides welding methods such as surfacing and sleeve welding have been used as repair of damaged gas pipelines in foreign countries. Importance of safety management of city gas pipelines have been emphasized recently and our own repair manuals and codes for repair of city gas pipelines are required. It is right time to conduct research on the composite repair methods since the composite repair was introduced rather recently compared to the welding repair methods which have been investigated for long time. In this study, as a starting point of safety assessment of gas pipeline repaird by composite materials, structural analysis of gas pipeline repaired by carbon fiber composite materials was conducted using finite element analysis(FEA) method and the results was discussed.

• Journal of the Korean Institute of Gas
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• v.11 no.1 s.34
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• pp.18-22
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• 2007

The fault current through the earth originated from a power line ground fault might cause arcing through the soil to an adjacent pipeline, which might bring about not only a catastrophic accident such as gas explosion and oil leakage but also a hazard to the safety of workers responsible for the maintenance and repair of the pipeline. In this paper we investigated the arcing phenomena through soil between a power line tower and a pipeline and outlined the standards for the separation distance of a buried pipeline adjacent to the power line tower.

• Journal of the Korean Institute of Gas
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• v.6 no.1 s.17
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• pp.10-16
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• 2002

This paper introduces developed prototype intelligent pig which detects corrosion on pipeline by using Magnetic Flux Leakage technology. The 8 inch developed MFL(Magnetic Flux Leakage) pig is composed of 5 yokes which magnetize pipeline wall and 45 Hall sensors which detect MFL signal. The designed MFL modules are analyzed by using magnetic circuit method in order to confirm whether pipeline wall is fully saturated. A variety of artificial defects are manufactured on 8 inch diameter steel pipeline in order to acquire MFL signals. So leakage flux of the axial, radial and circumferential component was acquired as defects. The results of this paper show that design technique for 8 inch MFL pig can be applied to large diameter MFL pig and 0.5mm defect depth can be detected.

• Journal of Korean Society for Quality Management
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• v.45 no.4
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• pp.649-664
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• 2017

Purpose: This paper introduces the technology of prognostics for Industry 4.0 and presents its application procedure for fitness-for-service assessment of natural gas pipelines according to ISO 13374 framework. Methods: Combining data-driven approach with pipe failure models, we present a hybrid scheme for the gas pipeline prognostics. The probability of pipe failure is obtained by using the PCORRC burst pressure model and First Order Second Moment (FOSM) method. A fuzzy inference system is also employed to accommodate uncertainty due to corrosion growth and defect occurrence. Results: With a modified field dataset, the probability of failure on the pipeline is calculated. Then, its residual useful life (RUL) is predicted according to ISO 16708 standard. As a result, the fitness-for-service of the test pipeline is well-confirmed. Conclusion: The framework described in ISO 13374 is applicable to the RUL prediction and the fitness-for-service assessment for gas pipelines. Therefore, the technology of prognostics is helpful for safe and efficient management of gas pipelines in Industry 4.0.