• 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 Earthquake Engineering Society of Korea
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• v.27 no.5
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• pp.213-220
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• 2023

Seismic fragility curves play a crucial role in assessing potential seismic losses and predicting structural damage caused by earthquakes. This study compares non-sampling-based methods of seismic fragility curve derivation, particularly the probabilistic seismic demand model (PSDM) and finite element reliability analysis (FERA), both of which require employing sophisticated finite element analysis to evaluate and predict structural damage caused by earthquakes. In this study, a three-dimensional finite element model of API 5L X65, a buried gas pipeline widely used in Korea, is constructed to derive seismic fragility curves. Its seismic vulnerability is assessed using nonlinear time-history analysis. PSDM and a FERA are employed to derive seismic fragility curves for comparison purposes, and the results are verified through a comparison with those from the Monte Carlo Simulation (MCS). It is observed that the fragility curves obtained from PSDM are relatively conservative, which is attributed to the assumption introduced to consider the uncertainty factors. In addition, this study provides a comprehensive comparison of seismic fragility curve derivation methods based on sophisticated finite element analysis, which may contribute to developing more accurate and efficient seismic fragility analysis.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.44-48
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• 2001

The pipelines for natural gas transmission were buried in the ground of 1.5m depth. The pipelines were continuously subjected to vehicle load and internal pressure change by the quantity consumed of natural gas. In this paper, high cycle fatigue properties of natural gas transmission pipelines were studied. Fatigue specimens were obtained from the base and weld metal of circular pipe. Fatigue strength increased with increasing yield strength. Especially, the fatigue strength of base metal was higher than the yield strength of base metal and the fatigue strength of weld metal by manufactured process of TMCP.

• Proceedings of the KIEE Conference
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• 2005.11c
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• pp.53-55
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• 2005

Because of the continuous growth of energy consumption and also the tendency to site power lines and pipelines along the same route, the close proximity of power lines and buried metallic pipelines has become more and more frequent. The lightning strokes collected by an electric substation or power line tower might cause arcing through the soil to an adjacent gas pipeline. This paper gives the review of the breakdown mechanism and the standards of separation distance between lower and pipelines.

• Journal of the Korean Institute of Gas
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• v.24 no.2
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• pp.22-28
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• 2020

In this study, quantitative risk assessment was carried out for city gas high-pressure pipelines crossing through urban rivers. The risk assessment was performed based on actual city gas properties, traffic volume and population and weather data in the worst case scenario conditions. The results confirmed that the social and individual risks were located in conditionally acceptable areas. This can be judged to be safer considering that the risk mitigation effect of protecting the pipes or installing them in the protective structure at the time of the construction of the river buried pipe is not reflected in the result of the risk assessment. Also, SAFETI v8.22 was used to analyze the effects of wind speed and pasquil stability on the accident damage and dispersion distances caused by radiation. As a result of the risk assessment, the safety of the pipelines has been secured to date, but suggests ways to improve safety by preventing unexpected accidents including river bed changes through periodic inspections and monitoring.

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.532-534
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• 2004

The advancement of electronics and telecommunication technologies has forced the risk management system for underground metallic structures to evolve into the remote monitoring and control system. Especially, facilities such as gas pipelines, oil pipelines and water distribution lines might make hazardous effect on human safety without continuous monitoring and control. As a result, pipeline engineers have applied cathodic protection system to prevent the degradation of their facilities by corrosion and carried out a periodic monitoring of the pipe-to-soil (P/S) potentials at numberous test boxes along their pipelines. The latter action on a road in downtowns, however, is so much dangerous that the inspectors should be ready to suffer the threatening of their lives and maintenance. In order to minimize these social costs and hazards, a stand-alone type corrosion monitoring equipment which can be installed in test box, store the P/S data for given Belied and send the data by wired/wireless telecommunications is under development. In order to obtain the exact P/S data, however, a reference electrode should be located as close to the pipeline as possible. Actually, the measured potential by a conventional portable reference electrode contain inevitably an IR drop portion caused by the current flow from the cathodic protection rectifier or the subway railroad. To minimize this error, it is recommended that the reference electrode should be buried within 10 cm from the pipeline. In this paper, we describe the design parameters for fabricating the permanent type reference electrode and the characteristics of the developed reference electrode.

• Journal of the Korean Institute of Gas
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• v.12 no.4
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• pp.8-13
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• 2008

The stray current interference problem could induce the corrosion of near-by structure and rail itself. Many efforts has been concentrated on the reduction of the interference. In this work the influences of separation distance, soil resistivity, pipe coating resistance, leak resistance of rail were studied using the numerical analysis methods. These analysis could be used to estimate the sensitivity of each variables in the study of the mitigation method and their numerical analysis.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.3
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• pp.263-269
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• 2003

Magnetic flux leakage (MFL) signals were used for corrosion inspection of buried oil and gas pipeline. 3D finite element analysis was used to examine the effects of far and near-side pit depth and tensile stress on MFL signals. Anisotropci materials were used, and the effects of simulated tensile stress on MFL were investigated. The axial and radial MFL signals depended on far and near-side single pit depth and on the bulk stress, but the circumferential MFL signal did not depend on them. The axial and radial MFL signals increased with increasing pit depth and the bulk stress, but the circumferential MFL signal was scarcely changed.

• Journal of the Korean Institute of Gas
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• v.12 no.1
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• pp.19-24
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• 2008

Due to industrialization and urbanization, underground metallic utilities with different owners have been rapidly increased and cathodic protection (CP) methods, especially impressed current CP systems, have been widely adopted to protect their utilities from corrosion with expanded recognition of this method. The stray current interference problem as well as the difficulty in spatial security for system installation, however, came to a ramification of which each owner couldn't resolve for himself. In this respect, this paper illustrates a field-diagnosed example for mutual interference due to separately operated CP systems and suggests an alternative method to overcome the interference situation by design and field-assessment of a common anode bed cathodic protection system.

• Journal of Advanced Research in Ocean Engineering
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• v.2 no.3
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• pp.99-111
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• 2016

Seabed affected by scouring, sedimentation, and siltation occurrences often cause exposure, which induces risks to existing structures or crude oil or gas pipeline buried subsea. In order to prevent possible risks, more economical structure installation methodology is proposed in this study by predicting and managing the risk. Also, the seabed does not only consist of sandy material, but clayey soil is also widespread, and the effect of undrained shear strength should be considered, and by cyclic environmental load, pore water pressure will occur in the seabed, which reduces shear strength and allows particles to move easily. Based on previous research regarding sedimentation or erosion, the average value of external environmental loads should be applied; for scouring, a 100-year period of environmental conditions should be applied. Also, sedimentation and erosion are mainly categorized by the bed load and suspended load; also, they are calculated as the sum of bed load and suspended load, which can be obtained from the movement of particles caused by sedimentation or erosion.