• Corrosion Science and Technology
• /
• v.21 no.5
• /
• pp.372-380
• /
• 2022

The external corrosion control of buried pipes can be achieved by a combination of coatings and cathodic protection to maximize effectiveness. One of the factors affecting cathodic protection is the environmental soil conditions. Because soil is a kind of electrolyte, the environmental conditions of soil may be changed by the atmospheric environment. Therefore, in this study, changes in environmental soil factors by atmospheric environmental factors were monitored. In cathodic protection, on-potential and off-potential were measured from December 2021 to July 2022. The effects of external environmental factors and soil environmental factors on cathodic protection were analyzed. Changes in outdoor temperature affected soil temperature, and soil conductivity had a proportional relationship with soil humidity, but outdoor humidity and precipitation did not significantly affect humidity and conductivity of the soil. In contrast, in cathodic protection, the on-potential was affected by temperature, humidity, the conductivity of the soil, and the anode used, but the off-potential was little affected by these factors.

• Journal of the Korean GEO-environmental Society
• /
• v.11 no.8
• /
• pp.73-82
• /
• 2010

The GFRP(Glass-Fiber Reinforced Plastic) pipe is designed to behave safely against the external forces and to secure stability of deformation and settlements of pipe, since it is laid under the ground. In this study, the evaluation for the pressure stability was carried out by performing the laboratory experiments to figure out the mechanical properties of Glass-Fiber Reinforced Plastic pipe, take a theoretical approach, and suggest the mechanical properties necessary for the analysis and design of GFRP. Numerical analysis is also conducted to evaluate on the field application through the comparison concerning relations between deformation and differential settlement in the GFRP and hume pipes when all and half sections are under the surcharge load.

• Journal of the Korean Institute of Gas
• /
• v.15 no.3
• /
• pp.58-66
• /
• 2011

This study presents the behavior characteristics of buried three-layered pipeline subjected to pile driving loads. The analysis considered the driving energy caused by 7 tonf of ram weight and 1.2m of stroke. Also the distance from vibration resource to pipeline varies in 5m to 30m. The vibration velocity and stress are investigated at the center of pipeline in longitudinal direction. In the same cover depth, attenuation ratio of vibration velocity and von Mises stresses for distance increment has shown a decreasing trend. The maximum stress occurs at the top and bottom for the inner pipe, however, an irregular stress distribution is found for the outer pipe.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2010.05a
• /
• pp.1710-1715
• /
• 2010

Service life of water pipes buried in the underground is considerably affected from various factors such as environmental characteristics, pipe characteristics, operation and maintenance, etc. Therefore it is difficult to determine their service life as uniformly the same value assigned by related laws and ordinances. As a result, the service life should be determined by the technical judgement based on the assessment for the condition of water pipes. In this study, It was established that the methodology could predict present and future failure risk, and plan short and long-term strategies for replacement/rehabilitation through the assessment for the physical deterioration and economical values of buried water pipe. The methodology was applied for the verification and reliability to several sites selected in multi-regional transmission pipelines. The proposed method could helps to support reasonable and economical decision of rehabilitation/replacement in the present and future. To improve conventional assessment method of aged water pipes, affecting factors are simplified based on the statistical analysis results from the measured data in the field and the physical deterioration mechanism for better reliability. Also, the guide-line is developed to carry out the reasonal rehabilitation planning through water pipe condition assessment.

• Korean Journal of Materials Research
• /
• v.32 no.3
• /
• pp.168-179
• /
• 2022

Microbiologically Influenced Corrosion (MIC) occurring in underground buried pipes of API 5L X65 steel was investigated. MIC is a corrosion phenomenon caused by microorganisms in soil; it affects steel materials in wet atmosphere. The microstructure and mechanical properties resulting from MIC were analyzed by OM, SEM/EDS, and mapping. Corrosion of pipe cross section was composed of ① surface film, ② iron oxide, and ③ surface/internal microbial corrosive by-product similar to surface corrosion pattern. The surface film is an area where concentrations of C/O components are on average 65 %/16 %; the main components of Fe Oxide were measured and found to be 48Fe-42O. The MIC area is divided into surface and inner areas, where high concentrations of N of 6 %/5 % are detected, respectively, in addition to the C/O component. The high concentration of C/O components observed on pipe surfaces and cross sections is considered to be MIC due to the various bacteria present. It is assumed that this is related to the heat-shrinkable sheet, which is a corrosion-resistant coating layer that becomes the MIC by-product component. The MIC generated on the pipe surface and cross section is inferred to have a high concentration of N components. High concentrations of N components occur frequently on surface and inner regions; these regions were investigated and Na/Mg/Ca basic substances were found to have accumulated as well. Therefore, it is presumed that the corrosion of buried pipes is due to the MIC of the NRB (nitrate reducing bacteria) reaction in the soil.

• Explosives and Blasting
• /
• v.22 no.3
• /
• pp.13-26
• /
• 2004

This work reports results of our study on the dynamic response of buried pipelines depending on their boundary conditions. We have studied behavior of the buried pipelines both along the axial and the transverse direction with a boundary condition of free ends. The buried pipelines are modeled as beams on elastic foundation while the seismic wave as a ground displacement in the form of a sinusoidal wave. The natural frequency, its mode, and the effect of parameters have been interpreted in terms of the free vibration. In order to investigate the response on the earthquake, the resulting frequency and the mode shape obtained from the free vibration have been utilized to derive the mathematical formula for the farced vibration. We have also completed the computer program to simulate the time-displacement graphs of the pipe lines with free ends for both cases of vibrations.

• Journal of the Korean Geophysical Society
• /
• v.1 no.1
• /
• pp.59-68
• /
• 1998

Ground penetrating radar (GPR) experiments were performed in a sand tank to study the ability of detection of buried pipes and to characterize the signal of the reflection wave. The ratios of diameter of buried pipes to the depth were set 4 up to 24 % and materials were metal, synthetic resin, and wood. In case of groundwater table below buried materials, strong reflection signals were observed irrespective of diameter and depth except for wood. While it is very difficult to detect the reflection signals in case that the groundwater table is set to higher than buried materials. The reflection signals from the bottom of the sand tank, however, were clearly observed even in case of higher groundwater table. This implies that the weak reflection signals from the buried materials are not all due to the wave attenuation. The vertical reflection profiling method is recommended in case that the object of the survey is to find horizontal position of buried material because this method has the advantage in cost and time of survey. However, the full or partial CMP gather method is recommended in case that the objects of the survey are to get the detailed subsurface information, i.e. the depth to buried material, interval velocity of geological layer, and mapping the groundwater table.

• Geotechnical Engineering
• /
• v.5 no.2
• /
• pp.19-32
• /
• 1989

The vertical loads of buried Hume pipes were calculated using the finite element method, in which the hyperbolic soil model, the nonlinear hysteretic stress path model and soil-structure interface model were used. The obtained results were compared and discussed with those from the classic methods such as Marston-Spangler's theory and so on. The effects of excavation width and depth to the top of pipe along with soil parameters and type of excavation, which have not been included in the classic methods, were investigated. In addition, a calculation method of the vertical load for buried Hume pipes was proposed and it is presumed to be easily applied in the practical fields.

• Proceedings of the KIEE Conference
• /
• 2005.07d
• /
• pp.2732-2734
• /
• 2005

In present, most of metallic structures(gas pipeline, oil pipeline, water pipeline, etc) are running parallel with subway and power line in seoul. Moreover subway system and power line make a stray current due to electrical corrosion on metallic structures. The owner of metallic structures has a burden of responsibility for the protection of corrosion and the prevention against big accident such as gas explosion or soil pollution and so on. So, they have to measure and analyze the data about P/S(Pipe to Soil) potential due to stray current of subway system. So, we have developed the Real-time Wireless Remote Monitoring System for Stray Current of Subway System. In this system, the permanent buried type reference electrode is necessary. In this paper, results of development about the permanent buried type reference electrode($Cu/CuSO_4$) are presented.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.21 no.4
• /
• pp.80-86
• /
• 2017

The purpose of this study is to construct a pattern database of pipes and cavities buried in the ground to prevent ground subsidence. To do this, it developed a pattern template algorithm using Open CV and applied it to the results of GPR detection results of tank. As a result, proper pattern database construction was possible. Since the results of this study are based only on limited experimental results, it is expected that more realistic data will be constructed if various field data and detection results of large test beds are supplemented in the future.