Abstract The origin of more than 90% in service pipeline failures is attributed to the presence of stress concentration areas such as defects in forms of gouges, dents, or when these defects are present together. These defects are provoked by external factors interferences, for instance by excavation machines. The influence of the dent depth on the burst pressure of the pipeline was evaluated. An approach based on a simple local strain criterion has been proposed to predict the damage and the failure of evaluated dented pipe. To validate a purely empirical rule, which specifies that a critical depth dent is equal to 10% of outside diameter of the pipeline, a series of mechanical tests (denting tests and burst tests) were conducted. Finite element analysis used in order to compare the numerical and experimental results. Experimental results showed that a single dent did not affect the burst pressure of the investigated specimens; therefore the rule of a critical depth of dent equal to 10% was found very conservative.
Safety, reliability and risks associated with water, oil and gas pipeline , Safety, reliability and risks associated with water, oil and gas pipeline , کتابخانه دیجیتال جندی شاپور اهواز
Last. Robert Akid(SHU: Sheffield Hallam University)H-Index: 26
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A numerical model has been established in order to simulate the propagation of pressure waves in water networks. The present model formulation is based on a system of partial hyperbolic differential equations. This system has been solved via the characteristics method. The current model provides the necessary data and the necessary damping of water hammer waves, taking into account the structure of the pipe network and the pressure loss. The numerical algorithm estimates the maximum pressure val...
Abstract The possibility of the application of ductile fracture criteria to the formability prediction of sheet metals is examined. Some criteria in simple forms are employed and combined with the finite element simulation of sheet metal forming. From the calculated histories of stress and strain in each element, the fracture initiation site and the forming limit are predicted by means of the criteria for ductile fracture. The material constants in the criteria are determined from uniaxial and p...
Abstract Axisymmetric deep drawing processes of laminates composed of mild steel and various aluminium alloy sheets are simulated by FEM. From the calculated stress and strain histories of elements in each layer, the fracture initiation site and the forming limit are predicted by using the ductile fracture criterion. The predictions so obtained are compared with experimental observations. The results exhibit that various types of fracture initiations in deep drawing of the laminated composite sh...
Last. G. W. Rowe(University of Birmingham)H-Index: 13
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This paper describes the use of the finite-element technique to predict fracture initiation in a range of simple metalforming operations. These cover typical processes and enable deformation and fracture initiation to be examined under several different loading conditions. Three types of metalforming operation are considered, simple upsetting, axisymmetric extrusion, and strip compression and tension
Abstract Criteria for ductile fracture of pore-free materials and porous materials are described. A method of estimating material constants in these criteria is also given. Applications of the criteria to prediction of the fracture strain in several types of metal working processes for pore-free materials and porous materials are described. These processes involve various strain paths and stress paths; in other words, various paths of hydrostatic stress component — which has a great effect on fr...
Current research aimed at explaining the mechanism of line-pipe fractures caused by third-party damage is discussed. Although researchers are still unable to accurately predict the failure stress of damage-induced flaws, many of the variables leading to an eventual line-pipe failure have been identified. Further research in this area will provide a means of predicting the behavior of the fracture-initiation process.
Abstract null null Constrained dents normally cause serious plastification on the pipe under internal pressure due to the restraint of the indenter. Therefore, in this work, the strain response of the API 5 L X80 (referred to as X80 in the remainder part) steel pipeline containing a constrained dent was investigated. Firstly, the formation process of the constrained dented pipeline was numerically simulated by establishing a 3D finite element (FE) model. The model was then verified against the t...
Abstract null null Reinforced Thermoplastic Pipe (RTP) is a flexible composite pipe that currently receives fair acceptance in the oil and gas industry, with high potentials to be used as a replacement to the carbon steel (CS) pipes especially in high corrosive environment. As RTP is relatively new products, their designs and qualifications are governed by the industry practice at present in the absence of comprehensive technical design standards. Most literatures to date are mainly dedicated to...
Abstract null null Dents have been identified as among the most common deformation defects in oil and gas pipelines. In this study, the multidimensional mechanical responses, springback, and rerounding behaviors of dents as well as the interaction of multiple dents on pipelines and their effect on pipe integrity were investigated through the three-dimensional finite element method and full-scale burst tests. The burst test demonstrates that a plain dent has a minimal effect on the pipeline burst...
Abstract: Burst pressure is the key to the design of pressure pipelines, and its accurate prediction is of considerable significance to pipeline safety and integrity management. Due to the different corrosion forms of different pipelines, the traditional empirical formula is difficult to predict the burst pressure with high accuracy. This paper proposes an ensemble data-driven model that can train the model based on existing pipeline parameters, corrosion characteristics, and burst pressure data...
Last. Guojin Qin(SWPU: Southwest Petroleum University)H-Index: 8
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Abstract In this work, a rigorous 3D finite element (FE) model was established to investigate the mechanical behavior of buried DN110 High-density polyethylene (HDPE) pipe with a scratch defect under land subsidence. Parametric effects, including soil gravity, defect geometric, operating pressure, transition section length, and land subsidence displacement, were investigated to analyze the significance of each factor on von Mises equivalent stress. Then the land subsidence displacement was selec...
Abstract A failure of a subsea crude oil API 5L X52 welded steel pipeline with an 18-inch outside diameter has caused oil leakage and this event was reported after 20 years in service. Based on the post-failure investigation, it was found that there was a circumferential through-wall crack in the center of the plain dent at the leak point of the pipeline. This study investigates the role performed by the dent in the failure mode of the pipeline. Macroscopic and microscopic observation revealed t...
The mechanical damages created on buried pipelines by any external activities are important consideration to assess the structural integrity of pipelines. The damages could be in the form of corrosion, dent, crack, gouge or any combination of these. A dent is a permanent inward plastic deformation in the pipe wall. The dents may not immediately cause failure of the pipe. However, it can reduce the pipe’s structural capacity and cause rupture or leak in the long run. The current researches focus ...
Last. Linya Li(SWPU: Southwest Petroleum University)
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Abstract Dent is one of the most common defects in mechanical damage of oil and gas pipelines. Most of the dents generated during pipeline construction are unconstrained dents, and rebound will occur during service of the pipeline. The dent defect can be considered as ductile damage. Taking X52 steel pipe as the research object, the rebound process of unconstrained dents in service is numerically simulated. Based on the Oyane ductile fracture criterion, the ductile damage degree of dented pipes ...