• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3169-3171
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• 2000

Most metal structures such as gas pipelines. oil pipelines, hot water pipelines and power cables etc. are buried in underground. Normally. metal structures corrode in underground by the electrochemical reaction. Then, metal structures need to be protected against corrosion. Cathodic protection is one of useful methods to protect metal structures against corrosion. In this paper we do the design of anode shape using Boundary Element Method. So we analysis the current density of anode surface and the potential distribution in the electrolyte. Therefore we seek to maximize the anode life and the safety of metal structures.

• Proceedings of the KIEE Conference
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• 2000.07a
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• pp.458-460
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• 2000

In this paper, we analyze the inductive coupling between overhead power transmission lines and neighbouring gas pipelines or other conductors, when they parallel to a line section in a phase-to-earth fault is assumed on the transmission line. A numerical procedure employing the finite-element method(FEM) is used in conjunction with Faraday's law, in order to predict the current in a faulted transmission line as well as the induced voltages across points on a pipeline running parallel to the faulted line and remote earth. The results lead to conclusion that may be useful to power system engineers.

• Journal of Magnetics
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• v.16 no.1
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• pp.36-41
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• 2011

If gas is leaking out of gas pipelines, it could cause a huge explosion. Accordingly, it is important to ensure the integrity of gas pipelines. Traditionally, over the years, gas-operating companies have used the ILI system, which is based on axial magnetic flux leakage (MFL), to inspect the gas pipelines. Relatively, there is a low probability of detection (POD) for the axial defects with the axial MFL-based ILI. To prevent the buried pipeline from corrosion, it requires a protective coating. In addition to the potential damage to the coating by environmental factors and external forces, there could be defects on the damaged coating area. Thus, it is essential that nondestructive evaluation methods for detecting axial defects (axial cracks, axial groove) and damaged coating be developed. In this study, an electromagnetic acoustic transducer (EMAT) sensor was designed and fabricated for detecting axial defects and coating disbondment. In order to validate the performances of the developed EMAT sensor, experiments were performed with specimens from axial cracks, axial grooves, and coating disbondment. The experimental results showed that the developed EMAT sensor could detect not only the axial cracks (minimum 5% depth of wall thickness) and axial grooves (minimum 10% depth of wall thickness), but also the coating disbondment.

• Earthquakes and Structures
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• v.12 no.3
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• pp.321-332
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• 2017

The reverse fault is a dangerous geological hazard faced by buried steel pipelines. Permanent ground deformation along the fault trace will induce large compressive strain leading to buckling failure of the pipe. A hybrid pipe-shell element based numerical model programed by INP code supported by ABAQUS solver was proposed in this study to explore the strain performance of buried X80 steel pipeline under reverse fault displacement. Accuracy of the numerical model was validated by previous full scale experimental results. Based on this model, parametric analysis was conducted to study the effects of four main kinds of parameters, e.g., pipe parameters, fault parameters, load parameter and soil property parameters, on the strain demand. Based on 2340 peak strain results of various combinations of design parameters, a semi-empirical model for strain demand prediction of X80 pipeline at reverse fault crossings was proposed. In general, reverse faults encountered by pipelines are involved in 3D oblique reverse faults, which can be considered as a combination of reverse fault and strike-slip fault. So a compressive strain demand estimation procedure for X80 pipeline crossing oblique-reverse faults was proposed by combining the presented semi-empirical model and the previous one for compression strike-slip fault (Liu 2016). Accuracy and efficiency of this proposed method was validated by fifteen design cases faced by the Second West to East Gas pipeline. The proposed method can be directly applied to the strain based design of X80 steel pipeline crossing oblique-reverse faults, with much higher efficiency than common numerical models.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.177-180
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• 2006

This study is to make a basic study if solid zinc (Zn) can be used for buried reference electrode, so we examined the adequacy of zinc as reference electrode by using zinc which showed regular electrode for buried period. The deference of electric potential if zinc electrode for corrosion factor such as soil resistivity or pH didn't show fixed trend and there was no clear trend on the change of measurement period. From field test, it is known that the natural electric potential difference of CSE electrode and zinc electrode is 1,100mV, but the electric potential of zinc electrode for CSE electrode in the natural soil and copying soil was 1,094~1,158mV. There was no fixed trend on the change of measurement period and electric potential difference of zinc electrode for corrosion factors such as soil resistivity or pH. Consequently, there was 40~60mV of electric potential difference in every copying soil during the experiment measurement.

• Corrosion Science and Technology
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• v.2 no.3
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• pp.161-163
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• 2003

With the development of Chinese petroleum and gas industry, about 20,000 km long-distance pipeline and 250,000 km gathering pipeline have been constructed in China. After operating for many years, most of the coatings on buried pipelines have aged so severe that the steel pipes are subject to corrosion environment underground. Focusing on the need of external coating for buried pipeline rehabilitation, a new type of coating has been developed. The development and application of the coatings has been introduced in this paper.

• Journal of the Korean Society of Hazard Mitigation
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• v.11 no.1
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• pp.59-66
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• 2011

Lifeline Damages induced by earthquake loading brings not only a structure damage but the communication problems by the interruption of various energy utilities such as electric power, gas, and water resources. Earthquake loss estimation systems in USA and Japan, called as HAZUS (Hazard in US) and HERAS (Hazards Estimation and Restoration Aid System), respectively, have been established for the purpose of efficient responding to the earthquake hazard. Sufficient damage records are required to establish these systems. However, there are insufficient data set of damage records obtained from previous earthquakes in Korea. In this study, according to the construction specifications of the pipelines in both Korea and USA, the behavior of both ductile and brittle pipelines embedded in dense sand overlying various soils, such as clay, sand, and gravel were examined with respect to the pipeline characteristics under various earthquake loadings. The applicability of pipeline damage prediction used in HAZUS program to Korea has been investigated.

• Journal of the Korean Institute of Gas
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• v.20 no.4
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• pp.50-57
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• 2016

According to the urban gas business legislation, cathodic protection systems should be applied for buried steel gas pipelines to prevent corrosion. In advanced countries including United States, the criteria for Cathodic Protection Potential is at least -850mV with respect to a saturated copper/copper sulfate electrode(CSE) when the CP applied, and the IR drops must be considered for valid interpretation. However, the IR drop through the pipe to soil boundary has been neglected in Korea. According to KGS code, a reference electrode must be placed in proximity to gas pipelines possible when measuring the CP potential. In this study, we have installed several solid reference electrodes around the buried pipeline(1.2m depth), lower surface(0.5m depth), and the surface individually in order to measure the CP potentials through the each reference electrode and find out the IR drops according to the location of each reference electrode. We have found the IR drop is the greatest when measuring the CP potential through the electrode placed on the ground and the IR drop is the smallest through the electrode installed near pipeline. Therefore, we have suggested the solid reference electrode should be installed as close as possible to buried pipeline in order to measure the correct CP potential without IR drop. We have also suggested the amendment of CP criteria considering IR drop.

• Journal of Energy Engineering
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• v.17 no.4
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• pp.204-211
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• 2008

Polyethylene(PE) pipes have been widely used as they are easy to construct and suitable for economical efficient when they are compared with metal pipelines. This paper studied the effect of various external loadings on stress and deflection of the buried PE pipes using Finite Element Method(FEM). For this purpose, stresses of buried PE pipes were calculated according to the loading condition such as pipe types(pipe diameter $50{\sim}400mm$), burial depths($0.6{\sim}1.2m$) and internal pressures($0.4{\sim}4bar$). As a result, it was founded the effect and relation with each of loading conditions under the buried condition.

• Proceedings of the KIEE Conference
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• 2003.11a
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• pp.379-381
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• 2003

The sharing of common corridors by electric power transmission lines and pipelines is becoming more common place. However, such corridor sharing can result in undesired coupling of electromagnetic energy from the power lines to the near facilities. This causes induced voltages on underground metallic pipelines due to the power line currents. This could cause AC corrosion in the pipeline, which could in turn lead to disastrous accidents, such as gas explosion or oil leakage. This paper investigates for the limitation of induced voltage on the buried metal structures which is used in the inside and outside of the country. And then we measure the earth resistance and leakage current of 22.9kV distribution lines and pipe to soil potential of near pipelines in Seoul Korea. Hereby we can see the leakage current flowing through the earthing electrode have an effect on near pipelines.