• 한국정밀공학회지
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• 제18권11호
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• pp.116-123
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• 2001

A failure probability model based on Von-Mises failure criterion and the standard normal probability function is proposed. The effects of varying boundary conditions such as nearby cavity, backfill, load cycle and corrosion on failure probability of the buried pipes are systematically investigated. The location of cavity is found to affect failure probability of buried pipeline within a certain limit. It is noted that the flexibility of backfill plays a great role to change the failure probability of buried pipeline. Furthermore, the corrosion gives less effects than other boundary conditions such as cavity, load as cavity, load cycle, and backfill to the failure probability of buried pipeline.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집A
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• pp.453-458
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• 2001

Pipelines have the highest capacity and are the safest and the least environmentally disruptive way for gas or oil transmission. Recently, failures due to corrosion defects have become of major concern in maintaining pipeline integrity. A number of solutions have been developed for the assessment of remaining strength of corroded pipelines. However, these solutions are known to be dependent on material properties and pipeline geometries. In this paper, a Fitness-For-Purpose type limit load solution for corroded gas pipelines made of the X65 steel is proposed. For this purpose, a series of burst tests with various types of corrosion defects are performed. Finite element simulations are carried out to derive an appropriate failure criterion. And then, further, extensive finite element analyses are performed to obtain the FFP type limit load solution for corroded X65 gas pipelines as a function of defect depth, length and pipeline geometry. And also, a window based computer program far the assessment of corrosion defect, which is named as COPAP(COrroded Pipeline Assessment Program) has been developed on the basis of proposed limit load solution.

• International Journal of Naval Architecture and Ocean Engineering
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• 제7권4호
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• pp.720-738
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• 2015

This study examined the dynamic response of a subsea pipeline under an impact load to determine the effect of the seabed soil. A laboratory-scale soil-based pipeline impact test was carried out to investigate the pipeline deformation/strain as well as the interaction with the soil-pipeline. In addition, an impact test was simulated using the finite element technique, and the calculated strain was compared with the experimental results. During the simulation, the pipeline was described based on an elasto-plastic analysis, and the soil was modeled using the Mohr-Coulomb failure criterion. The results obtained were compared with ASME D31.8, and the differences between the analysis results and the rules were specifically investigated. Modified ASME formulae were proposed to calculate the precise structural behavior of a subsea pipeline under an impact load when considering sand- and clay-based seabed soils.

• 한국가스학회지
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• 제2권2호
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• pp.26-33
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• 1998

매설 천연가스배관의 두께는 ANSI B3l.8의 요건에 따라 주로 내압과 위치인자로 결정된다. 그러나 실제 매설배관 응력에는 내압뿐아니라 여러 외부인자들이 작용하여 매설조건과 환경조건이 변화되면 배관의 응력이 달라진다. 환경요인 변화에 따른 안전도 감소를 피하기 위하여 응력을 평가하는 작업이 수시로 필요하다. 내압, 토하중, 차량하중, 지반침하에 의한 매설배관의 응력을 계산하는 적절한 수식이 개발되었으나 비전문가가 사용하기에 매우 어려운 단점이 있다. 따라서 본 연구에서는 매설배관의 응력상태를 손쉽게 계산할 수 있는 컴퓨터 프로그램을 개발하였다. 프로그램은 토하중, 차량하중, 열하중 및 네 가지 지반침하 발생시 배관에 생기는 최대응력을 계산하는 것으로서, 응력은 수식 또는 FEM에서 유추한 그래프에서 얻은 값이다. 본 논문에서는 첫 번째 논문에 이어 프로그램 작동방법과 원리를 설명하였다.

• 한국해양공학회지
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• 제26권2호
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• pp.1-7
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• 2012

DNV-OS-F101 includes the concept development, design, construction, operation,and abandonment of offshore pipeline systems. The main objective of this offshore standard (OS) is to ensure that pipeline systems are safe during the installation and operational period. The pipeline design philosophy also includes public safety and environmental protection. The mechanical wall thickness design of a pipeline shall follow the design objectives and safety philosophy. This new design code includes a very sophisticated design procedure to ensure a safe pipeline, public safety, and environmental protection. This paper presents the results of a parametric study for the wall thickness design of offshore pipelines. A design matrix was developed to cover the many design factors of pipeline integrity, public safety, and environmental protection. Sensitivity analyses of the various parameters were carried out to identify the impacts on offshore pipeline design.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.873-876
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• 2002

This paper presents the effect of internal corrosion, external corrosion, material properties, operation condition, earthquake, traffic load and design thickness in pipeline on the failure prediction using a failure probability model. A nonlinear corrosion is used to represent the loss of pipe wall thickness with time. The effects of environmental, operational, and design random variables such as a pipe diameter, earthquake, fluid pressure, a corrosion rate, a material yield stress and a pipe thickness on the failure probability are systematically investigated using a failure probability model for the corrosion pipeline.

• 한국신뢰성학회:학술대회논문집
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• 한국신뢰성학회 2002년도 정기학술대회
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• pp.403-410
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• 2002

This paper presents the effect of internal corrosion, external corrosion, material properties, operation condition, earthquake, traffic load and design thickness in pipeline on the failure prediction using a failure probability model. A nonlinear corrosion is used to represent the loss of pipe wall thickness with time. The effects of environmental, operational, and design random variables such as a pipe diameter, earthquake, fluid pressure, a corrosion rate, a material yield stress and a pipe thickness on the failure probability are systematically investigated using a failure probability model for the corrosion pipeline.

• Ocean Systems Engineering
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• 제4권4호
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• pp.279-291
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• 2014

Smart flanges are used for pipeline and riser repair in subsea. In a typical case in the gas export pipeline project, the end cap bolts of a 4inch smart flange were broken during operation, and in turn leakage occurred. This work presents the detail of three dimensional finite element analysis of the smart flange to support the observed end cap bolts failure. From finite element analysis it turns out that in the presence of external bending moment, an uneven contact distribution is present between seal and end cap, which in turn changes the uniform load distribution on bolts and threaten the integrity of bolts. On the other hand, 3D finite element analysis of interaction between pipeline and seabed is presented by means of Abaqus to explore the distribution of bending moment along the pipeline route. It is found that lateral buckling occurs in the pipeline which introduces large bending moment.

• 한국압력기기공학회 논문집
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• 제15권2호
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• pp.50-57
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• 2019

This paper investigates deformation characteristics of gas pipeline using the in-plane bending experiment and finite element analysis of a pipe bend. The effect of the bending angle and internal pressure on the deformation characteristics is analyzed. The pipe bend used in this study is API 5L X65 (out diameter: 20 inch) material with the thickness of 11.9 mm. The maximum load, displacement at maximum load, angle and local strain of 90° pipe bend are obtained from the in-plane bending experiment. Comparison between FE results and experimental data shows overall good agreements. In addition, the deformation characteristics of 22.5° and 45° pipe bend are calculated using the finite element analysis. As a result, the effect of the bend angle on the deformation characteristics is discussed.

• 한국해양공학회지
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• 제8권2호
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• pp.151-156
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• 1994

The equations of motion of a submarine pipeline with the internal flowing fluid and subject to hydrodynamic loadings are derived by using Hamilton's principle. Coupling between the bending and the longitudinal extension due to axial load and thermal expansion are considered. Coupling between the twisting and extension are not considered. The equations of motion are well agreed with the results which are derived by the vector method.