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1
Nsanzubuhoro, Rene. "Pressure-based leakage characterisation of bulk pipelines." Doctoral thesis, Faculty of Engineering and the Built Environment, 2019. http://hdl.handle.net/11427/30938.
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Water losses in distribution systems are a huge problem internationally and also in South Africa where more than a third of the water entering the water supply networks is lost through pipe leaks. With water demand increasing due to population growth and urbanisation, water resources are under greater stress and water supply failures are becoming more common. A great deal of work has been done over the past two decades on managing water losses in distribution systems. The Water Loss Task Force of the International Water Association (IWA) played a leading role in this effort, with the “IWA water balance” now widely used as a basis in municipal water loss programs. One of the areas that have received relatively little attention is leakage on bulk pipeline systems. Bulk pipelines connect water treatment plants to bulk reservoirs and distribute water from reservoirs to different towns or water supply zones. Bulk pipes may be operated using pumps or gravity, and generally do not supply consumers directly. It is difficult to determine what the water losses in a bulk pipeline are, as the high flow rates make it impractical or prohibitively expensive to measure flow rates at both ends of these pipelines. Cheaper solutions, such as clamp-on ultrasonic flow meters or reservoir drop tests, are prone to problems and do not have the required accuracy. Due to the lack of reliable and effective methods, water losses on bulk pipes are often assumed to be 2 or 3 %. However, these losses may, in fact, be much greater, and due to the large flow of water transported by bulk pipelines, even small fractions of losses represent large volumes of water. The aim of this project was to develop a method for identifying the size and type of leak present in real bulk water pipelines with minimal disturbance to the operation of the infrastructure. This was achieved by developing a mobile device called the pipe condition assessment equipment (PCAE), which uses pressure testing in combination with the latest models on the behaviour of leaks areas with pressure to assess the condition of the bulk pipeline. To verify the efficacy of the PCAE, the device was first tested on three uPVC pipes with known leakage characteristics in the laboratory (a 12mm round hole, 100mm by 1mm circumferential crack and a 100mm by 1mm longitudinal crack). As expected, the round hole had very small head-area slopes which are negligible, whilst the circumferential crack showed a negative head area slope and the longitudinal crack portrayed a large positive head-area slope. These results were consistent with previous laboratory experiments that investigated the behaviour of round holes and longitudinal and circumferential cracks. Bulk water suppliers and municipalities were then approached to take part in the study. Several bulk pipelines were tested using the PCAE. The results of the field test are discussed in terms of the pre-testing procedures to prepare for the tests, their repeatability and the effectiveness of the device to detect, quantify and characterise leakage on the pipeline. For pipelines with undetectable leakage, a non-intrusive technique that uses a dynamic pressure drop signature from an isolated pipe, to detect and quantify undetectable leakage, was developed. The leakage characteristics of the isolated pipe were estimated from the pressure vs time data. In summary, if the pressure remained constant the pipe was without a leak. If the pressure dropped, a novel mathematical model was fitted to the pressure vs time curve, using the known pipe properties, to determine the characteristics of the leak or leaks present in the pipe. Overall, the PCAE was capable of assessing the extent of leakage on a range of pipe materials, diameters and lengths. It was found that out of the eleven bulk pipelines tested in this study, three could not be tested due to dysfunctional isolation valves and failed connection points. The other eight pipelines that were successfully tested were found to be leaking. The effective initial leak areas for the tested pipelines ranged from 4.88mm2 to 137.66mm2 , whilst the effective head-area slope ranged from 0.0032 mm2 /m to 3.14 mm2 /m and the N1 leakage exponents were found to range from 0.56 up to 1.09. Finally, since there are no well-founded performance indicators for bulk systems, this study also described the findings from analyses of several potential performance indicators using the data from the bulk pipelines tested using the PCAE. The challenges in comparing water losses of different bulk pipelines are highlighted. Based on this, it was found that because every bulk pipeline has its unique characteristic regarding structural parameters such as diameter, pipe material, type of couplings, and operating pressure, the preferred performance indicator for assessing water losses in bulk systems mainly depends on the purpose of the analysis.
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Bradley, Michael S. A. "Prediction of pressure losses in pneumatic conveying pipelines." Thesis, University of Greenwich, 1990. http://gala.gre.ac.uk/14606/.
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This project arose out of a need to improve the accuracy with which the pressure drop along pneumatic conveying pipelines in process plant could be predicted. The methods previously available for making this prediction are examined and critically assessed. The need for a different method is shown, and a new approach is developed and tested. The new approach involves testing of the product to be conveyed, in a test pipeline at the smaller end of the industrial scale, with measurements being made of the pressure drop caused by bends and of the pressure gradients in straight lengths; the data is fed into a storage and retrieval system then extracted and used to predict the pressure drop in a plant pipeline conveying the same product. The method has been developed to the point where it is in current use for the design of pneumatic conveying systems for industrial applications. The development of a suitable test rig, the data storage and retrieval systems, and the method for predicting the pressure drop in a plant pipeline, are examined in detail. The method is tested against data from pipeline loops and found to give good results. A quantitative comparison is made against the work of other authors in the field; the results of this show good agreement although the scope of the current work is much wider than anything comparable. An assessment is also made of the areas requiring further work. A major advantage of the method lies in its use to predict the pressure drop along pipelines having steps up in bore size along their length, which were not amenable to treatment by previous methods. The advantages of such systems and the consequent value of the method are examined in detail.
3
Fallqvist, Björn. "Collapse of thick deepwater pipelines due to hydrostatic pressure." Thesis, KTH, Hållfasthetslära (Inst.), 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174084.
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The collapse-behaviour of pipes was to be studied by use of Finite Element modelling.Existing analytical expressions for collapse were evaluated and especially the one used inDNV-OS-F101 was decided to be studied in comparison with FE-model results.Parameters that may influence the collapse capacity and are not included in the analyticalexpressions –flattening, peaking, eccentricity, local wall thickness variation, materialstress-strain curve, residual stresses - were defined and explained. A model was built inthe Finite Element software package Abaqus v6.9.1 and several articles on collapsetesting used to verify it. The aforementioned parameters were studied by use ofsensitivity studies and the results shown and discussed. Effective thickness definitions foruse in the DNV-formula and the DNV-yield stress criterion were discussed in the contextof the results. The results seemed to indicate that the transition between the elastic andplastic range of the material stress-strain curve was of great importance. The results werediscussed in the context of the different collapse-related parameters defined beforehandand some concluding remarks were made on possible further work related to thesefindings.
4
Vancko, Robert M. "Effect of a drag reducing agent on pressure drop and flow regime transitions in multiphase horizontal low pressure pipelines." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1184354301.
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Alzuhd, Tahir Hussein Hasan. "Pressure losses associated with slurry flow in horizontal pipelines." Thesis, University of Hertfordshire, 2003. http://hdl.handle.net/2299/14146.
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The flow of solid liquid mixtures (slurries) has attracted much attention in research work because of its importance to industry. Prediction of pressure losses associated with slurry flow helps pipe designers select the correct pipe sizes for optimum energy consumption, equipment sizing and reliable operation of the pipeline networks. Many workers developed empirical correlations, but due to the randomness of the problem they seem of limited use in design applications because they do not contain an assessment except by trial and error, which is costly. The existence of more than one particle size poses more complexities to the slurry flow problem but it is in need in practical applications. The aims of this work are justified under the light of the observations on the state of the art in slurry transport. An experimental program is designed to highlight the effects of this problem through a predetermined set of test runs. The variables are grouped to optimise the number of experiments and to remove the effect of dimensions on the prediction method The test rig is built to serve the aims of this exercise and test runs conducted, results grouped and discussed for polyfractional slurries. A mathematical model is developed in the form of an empirical correlation. Statistical tests are employed to verify the goodness of fit. Finally, conclusions and recommendations for further work are listed.
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Abbassian, F. "Long-running ductile fracture of high pressure gas pipelines." Thesis, University of Cambridge, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372872.
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Sundara, V. "Transient flow dynamics in high pressure carbon dioxide pipelines." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1465047/.
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The purpose of this thesis is to model, investigate and where possible validate the impact of Emergency Shutdown Valve (ESDV) closure on mitigating the fugitive releases from failed CO2 pipelines employed as part of the Carbon Capture and Storage (CCS) chain. Additional mathematical modelling work is also presented for simulating steady-state fluid flow and mixing in CO2 pipeline networks containing the various types of impurities representative of the different capture technologies, including pre-combustion, post-combustion and oxyfuel. The pipeline rupture transient flow model, based on the numerical solution of the conservation equations using the Method of Characteristics, incorporates Wu’s Modified Peng-Robinson equation of state to deal with pipelines containing pressurised CO2. It utilises the homogeneous equilibrium flow (HEM) assumption, where the constituent phases in a two-phase mixture are assumed to be in thermal and mechanical equilibrium. The first part of this study focuses on the development and experimental validation of the CFD model for simulating the dynamic response of inline ESDV’s in limiting outflow following the rupture of pressurised pipelines. The model accounts for the pertinent valve characteristics including the activation and closure times as well as its proximity to the rupture location. The validation of the model involves comparison of its predictions against measurements taken following the controlled Full Bore Rupture (FBR) of a 113 m long, 0.15 m i.d. pipeline containing CO2 at 151 bara and 27 oC incorporating a ball valve along its length. The data recorded and simulated include the transient fluid temperatures and pressures immediately upstream and downstream of the closing valve following FBR. Excellent agreement between the two sets of data is obtained throughout the depressurisation process. The above is followed by the linking of the publically available SLAB dispersion model for heavy gas clouds to the validated outflow model. The combined model is then tested against existing experimental data from the CO2Pipetrans research project involving the blowdown of a 30 m long, 0.6 m i.d. of a CO2 pipeline from initial temperatures and pressures ranging 278 to 284 K and 104 to 156 bara respectively. The combined outflow and dispersion model is next used to determine the optimal spacing of ESDVs for CO2 pipelines. This is done by solving an optimisation problem involving trading off the 7 % (vol./vol.) CO2 concentration contour area (concentrations above this are considered fatal) against the cost for valve installation. Level diagrams are then used to determine the optimal separation distance for ESDVs. Finally, the problem of steady-state flow in pipeline networks is analysed. A flow model is developed to determine the required inlet pressure at CO2 source locations to obtain a specific delivery pressure for given source CO2 mixture compositions and flowrates. The model is then used in a realistic case study with two inlet sources and one delivery location. The required inlet pressures at the source locations are determined for given initial feed flowrates and compositions, to attain a desired delivery pressure. In addition, the downstream fluid temperature and fluid compositions are also determined.
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Manouchehri, Soheil. "Behaviour of subsea pipelines subjected to bending and hydrostatic pressure." Thesis, Heriot-Watt University, 2004. http://hdl.handle.net/10399/244.
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Sandford, Richard J. "Lateral buckling of high pressure/high temperature on-bottom pipelines." Thesis, University of Oxford, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.645946.
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On-bottom (or unburied) pipelines) which carry hydrocarbons across the seabed) are typically subjected to compressive axial loading arising from restrained thermal- and pressure-induced expansion. This compressive loading usually causes a nominally straight pipeline to buckle into a mode lying predominantly in the plane of the seabed; this response is widely termed lateral buckling. Predicting the response of an on-bottom pipeline to thermal and pressure-induced axial compressive loading is the primary focus of this thesis. In assessing whether or not the structural integrity of a pipeline is at risk during lateral buckling (and also in the post-buckling regime) finite element analyses are typically carried out. In these analyses) the pipeline is modelled as an assembly of beam elements while the connection between the pipe and the seabed is modelled using a macro-element) which defines the relationship between the loads and displacements of the pipe. In this thesis) the development) calibration and implementation of a macro-element model for use in lateral buckling design is described. The proposed macro-element model accounts for the response during lateral displacement of multiple pipe diameter amplitude (as appropriate to the movement of the crown of a buckle) as well as the reversals in the direction of lateral displacement due to intermittent shut-downs in the operation of the pipe. The model is of the hardening plasticity type and is cast in terms of vertical and horizontal force resultants. Results from numerical analyses (using both finite element limit analysis and the displacement-based incremental finite element method) are used to calibrate the model. Its performance is tested by examining the results of retrospective simulations of experimental tests. Finally) the results of field-representative structural analyses are presented) which demonstrate the suitability of the model for use in design practice.
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Venables, Robert. "Thermal behaviour of transient high pressure hydrocarbon systems." Thesis, Imperial College London, 1997. http://hdl.handle.net/10044/1/8020.
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Keefe, Daniel Anthony. "Thermal behaviour of transient high pressure high speed flowing systems." Thesis, Imperial College London, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.312028.
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Arfaie, Mehdi. "Pressure transient analysis including column separation and behaviour of long pipelines." Thesis, University of Newcastle Upon Tyne, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.330263.
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Maley, Lisa. "A study of slug flow characteristics in large diameter horizontal multiphase pipelines." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177090588.
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Gao, Xiang. "Hydrodynamics of HCP with slopes and bends /." free to MU campus, to others for purchase, 1999. http://wwwlib.umi.com/cr/mo/fullcit?p9962524.
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CARNEIRO, LEONARDO MOTTA. "STUDY OF THE DYNAMIC BEHAVIOR OF SPRING PRESSURE RELIEF VALVE FOR PIPELINES." PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIRO, 2011. http://www.maxwell.vrac.puc-rio.br/Busca_etds.php?strSecao=resultado&nrSeq=21693@1.
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PONTIFÍCIA UNIVERSIDADE CATÓLICA DO RIO DE JANEIROA grande maioria dos dutos de transporte de petróleo e derivados no Brasil trabalha com válvulas de alívio no projeto dos seus sistemas de proteção. Desta forma, o perfeito dimensionamento e funcionamento destas válvulas são fundamentais para garantir a segurança de dutos de transporte e dos terminais de carga e descarga, caso haja alguma condição anormal de operação que gere sobrepressões. Estas válvulas aliviam a pressão interna do duto caso a mesma ultrapasse um valor definido e calibrado na válvula. Simplificadamente, a válvula de alívio de pressão tipo mola possui um disco o qual é pressionado pela mola contra o bocal de entrada. Quando a pressão do duto se eleva, a força gerada na superfície do disco aumenta e, dependendo do ponto de ajuste da mola, supera a força exercida pela mesma fazendo com que o disco se eleve, descarregando pelo bocal de saída o fluido para o tanque de alívio e, consequentemente, reduzindo a pressão no duto. Desta forma, a válvula de alívio garante que o duto não seja submetido a pressões superiores às pressões de projeto, o que poderia levar a uma falha do duto e a um possível vazamento de produto para meio ambiente. Este trabalho propõe um estudo experimental e numérico para determinar o comportamento dinâmico de válvulas de alívio de mola. Foi realizada a montagem de uma bancada experimental com um circuito de água contendo uma bomba, uma válvula de alívio e uma válvula de bloqueio capaz de interromper o fluxo no circuito gerando um transiente de pressão que obriga a abertura da válvula para aliviar a pressão interna no sistema. A válvula de alívio foi instrumentada para medir as grandezas necessárias para estudar o comportamento dinâmico da válvula e os transientes de pressão e vazão gerados no duto. Os resultados experimentais foram comparados com os resultados obtidos de modelos computacionais proporcionando o aperfeiçoamento e validação destes modelos.
The majority of oil and refined product pipelines in Brazil employ pressure relief valves in the design of their protection system. Thus, the perfect design and operation of these valves is essential to ensure the safety of transport pipelines and loading and unloading terminals, under any abnormal condition of operation that generates overpressures. These valves work by relieving the internal pressure in case it exceeds a pre-set and calibrated value. In a nutshell, the spring-type pressure relief valve has a disk which is pressed by a spring against the inlet nozzle of the valve. When the pressure rises, the force generated on the surface of the disc increases and, depending on the pressure relief valve set point, the pressure force overcomes the force exerted by the spring, causing the disk to rise and thus discharging the fluid through the outlet nozzle to the relief tank, consequently reducing the pressure in the pipeline. Using this principle, the relief valve ensures that the pipeline is not subjected to high transient pressures, which could lead to pipeline or equipment rupture and possible product leak. The present dissertation describes a numerical and experimental study conducted to determine the dynamic behavior of spring-type relief valves. The experiments were conducted in a water pipe loop equipped a pump, a block valve to generate the pressure transients and a commercial spring-type pressure relief valve. The loop was instrumented with pressure, flow and temperature transducers. The relief valve was instrumented to measure the variables necessary to study the dynamic behavior of the valve and the transient pressure and flow generated in the pipeline. The experimental results were compared with results obtained from computer models allowing the improvement and validation of these models.
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Van, Deventer Christoffel Gerhardus. "Guidelines for predicting the remaining life of underground pipe networks that are subjected to the combined effects of external corrosion and internal pressure." Diss., Pretoria : [s.n.], 2002. http://upetd.up.ac.za/thesis/available/etd-10312005-113656/.
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Javaid, Muhammad Salik. "Measurement of pressure distribution around a circular cylinder on a plane wall in oscillatory flow." Diss., Georgia Institute of Technology, 1994. http://hdl.handle.net/1853/20733.
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Vancko, Jr Robert M. "Effect of a drag reducing agent on pressure drop and flow regime transitions in multiphase horizontal low pressure pipelines." Ohio University / OhioLINK, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1184354301.
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Wilkens, Robert Joseph. "Prediction of the flow regime transitions in high pressure, large diameter, inclined multiphase pipelines." Ohio University / OhioLINK, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1175023280.
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Fakroun, A., and Hadj Benkreira. "Rheology of waxy crude oils in relation to restart of gelled pipelines." Elsevier Ltd, 2019. http://hdl.handle.net/10454/17283.
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YesWaxy crude oils are pumped hot but upon power cut, pumping stops, the oil cools leading below the wax appearance temperature to precipitation of the wax and the formation of a gel throughout the pipe. In such a situation, what is the minimum pressure required to restart flow, not to merely deform the gel or break it? This paper provides a solution to this problem using microscopic observations under controlled cooling conditions and rheological data conducted in constant stress mode under controlled temperature and cooling conditions and restart experiments in laboratory pipelines replicating the rheometric conditions and deviations from them to inform large diameter operation in the field. Three important findings derive from the experimental data collected: (i) A fragmentation stress , rather than the static stress that precedes it, is found to be the more accurate predictor of flow re-start pressures; (ii) Waxy crude oils gels exhibit true yield stress and yielding process but also show flow on application of the slightest stress below yielding; (iii) This flow, in the elastic region, is jagged rather than continuous suggesting a consolidation process of the crystals and their agglomerates forming the gel. In the broader context of the existence of a yield stress, the data presented here show that there is such a thing as a yield stress and the concepts of a yield stress and that everything flows are not mutually exclusive.
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Daas, Mutaz A. "Effects of drag reducing agents on pressure drop and flow characteristics in multiphase inclined pipelines." Ohio : Ohio University, 2000. http://www.ohiolink.edu/etd/view.cgi?ohiou1171651331.
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Shi, Hua. "A study of oil-water flows in large diameter horizontal pipelines." Ohio : Ohio University, 2001. http://www.ohiolink.edu/etd/view.cgi?ohiou1178912194.
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Shabani, Behnam. "Wave-Associated Seabed Behaviour near Submarine Buried Pipelines." University of Sydney, 2008. http://hdl.handle.net/2123/3532.
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Master of Engineering (Research)Soil surrounding a submarine buried pipeline consolidates as ocean waves propagate over the seabed surface. Conventional models for the analysis of soil behaviour near the pipeline assume a two-dimensional interaction problem between waves, the seabed soil, and the structure. In other words, it is often considered that water waves travel normal to the orientation of pipeline. However, the real ocean environment is three-dimensional and waves approach the structure from various directions. It is therefore the key objective of the present research to study the seabed behaviour in the vicinity of marine pipelines from a three-dimensional point of view. A three-dimensional numerical model is developed based on the Finite Element Method to analyse the so-called momentary behaviour of soil under the wave loading. In this model, the pipeline is assumed to be rigid and anchored within a rigid impervious trench. A non-slip condition is considered to exist between the pipe and the surrounding soil. Quasi-static soil consolidation equations are then solved with the aid of the proposed FE model. In this analysis, the seabed behaviour is assumed to be linear elastic with the soil strains remaining small. The influence of wave obliquity on seabed responses, i.e. the pore pressure and soil stresses, are then studied. It is revealed that three-dimensional characteristics systematically affect the distribution of soil response around the circumference of the underwater pipeline. Numerical results suggest that the effect of wave obliquity on soil responses can be explained through the following two mechanisms: (i) geometry-based three-dimensional influences, and (ii) the formation of inversion nodes. Further, a parametric study is carried out to investigate the influence of soil, wave and pipeline properties on wave-associated pore pressure as well as principal effective and shear stresses within the porous bed, with the aid of proposed three-dimensional model. There is strong evidence in the literature that the failure of marine pipelines often stems from the instability of seabed soil close to this structure, rather than from construction deficiencies. The wave-induced seabed instability is either associated with the soil shear failure or the seabed liquefaction. Therefore, the developed three-dimensional FE model is used in this thesis to further investigate the instability of seabed soil in the presence of a pipeline. The widely-accepted criterion, which links the soil liquefaction to the wave-induced excess pressure is used herein to justify the seabed liquefaction. It should be pointed out that although the present analysis is only concerned with the momentary liquefaction of seabed soil, this study forms the basis for the three-dimensional analysis of liquefaction due to the residual mechanisms. The latter can be an important subject for future investigations. At the same time, a new concept is developed in this thesis to apply the dynamic component of soil stress angle to address the phenomenon of wave-associated soil shear failure. At this point, the influence of three-dimensionality on the potentials for seabed liquefaction and shear failure around the pipeline is investigated. Numerical simulations reveal that the wave obliquity may not notably affect the risk of liquefaction near the underwater pipeline. But, it significantly influences the potential for soil shear failure. Finally, the thesis proceeds to a parametric study on effects of wave, soil and pipeline characteristics on excess pore pressure and stress angle in the vicinity of the structure.
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Krishnamoorthy, Vijay. "Effect of gas density on corrosion in horizontal multiphase slug flow at high temperatures and pressures." Ohio : Ohio University, 1997. http://www.ohiolink.edu/etd/view.cgi?ohiou1177096097.
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Nugroho, Wibowo Harso 1967. "Monitoring of pipeline using smart sensors." Monash University, Dept. of Mechanical Engineering, 2001. http://arrow.monash.edu.au/hdl/1959.1/9236.
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Tullius, Lisa. "A study of drag reducing agents in multiphase flow in large diameter horizontal pipelines." Ohio : Ohio University, 2000. http://www.ohiolink.edu/etd/view.cgi?ohiou1181066439.
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Craveiro, Marina Vendl. "Upheaval buckling of pipelines triggered by the internal pressure resulting from the transportation of oil and gas: theoretical discussions and geometrically nonlinear analysis using Finite Element Method." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/3/3144/tde-06122017-082632/.
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The pipelines used to transport oil and gas from the wellheads to the distribution and refining sites can be subjected to high levels of pressure and temperature. Under such conditions, the pipelines tend to expand, but, if the expansion is inhibited, a significant compressive axial force can arise, leading to their buckling, which can occur in the horizontal or vertical plane. In this context, the objective of the present work is to analyze the upheaval buckling of pipelines, considering the internal pressure to which they are subjected during the transportation of oil and gas as its only triggering. Using the concept of effective axial force, it aims at discussing two different approaches for considering the internal pressure in buckling problems: distributed loads dependent on pipeline curvature and equivalent compressive axial forces with follower and non-follower characteristics. It also discusses the influence of using static or dynamic analysis for such approaches. Concerning the upheaval buckling itself, the work intends to analyze and compare the influence of the soil imperfection amplitudes to the influence of the friction between the pipeline and the ground in the critical loads and in the post-buckling configurations of the pipeline. Besides theoretical research, the objectives are achieved through the development of various numerical models, since geometrically-simple models, without the consideration of the interaction between the pipeline and the ground, until more complex models, with the use of contact models to detect the ground and its imperfections. The models are developed in Giraffe (Generic Interface Readily Accessible for Finite Elements) using geometrically-exact finite element models of beams, undergoing large displacements and finite rotations. Through the research, it is concluded that there is an equivalence between the application of the internal pressure as a distributed load dependent on pipeline curvature and the application of the internal pressure as a follower compressive axial force. Besides this, it is demonstrated that the type of the analysis (static or dynamic) depends on the nature of the physical system analyzed. With the aid of results presented in terms of internal pressure, classical results about the influence of the imperfection amplitudes and of the friction between the pipeline and the ground in buckling are confirmed. It is also showed that the imperfection amplitudes analyzed play a more important role in the post-buckling configurations of the pipeline than the friction.Os dutos utilizados para transportar petróleo e gás natural das reservas até os locais de distribuição e refino podem estar submetidos a elevados níveis de pressão e temperatura. Sob tais condições, os dutos tendem a se expandir, porém, se a expansão é inibida, uma força axial de compressão significativa pode surgir nos dutos, ocasionando a flambagem lateral ou vertical dos mesmos. Dentro desse contexto, o objetivo do presente trabalho é analisar a flambagem vertical de dutos, considerando a pressão interna à qual eles estão submetidos durante o transporte de petróleo e gás natural como o único parâmetro desencadeador da flambagem. Usando o conceito de força axial efetiva, o trabalho objetiva discutir duas abordagens diferentes para considerar a pressão interna nos problemas de flambagem: carregamentos distribuídos dependentes da curvatura do duto e forças axiais de compressão equivalentes à pressão com caráter seguidor e não seguidor. O trabalho também discute a influência de usar a análise estática ou dinâmica para analisar essas abordagens de carregamento. Com relação à flambagem vertical propriamente dita, o trabalho pretende analisar e comparar a influência das amplitudes das imperfeições presentes no solo com a influência do atrito entre o duto e o solo nas cargas críticas e nas configuração pós-críticas do duto. Além de pesquisa teórica, os objetivos são atingidos através do desenvolvimento de vários modelos numéricos, desde modelos geometricamente simples, sem a consideração da interação entre o duto e o solo, até modelos mais complexos, com o uso de modelos de contato para detectar o solo e suas imperfeições. Os modelos são desenvolvidos no Giraffe (Generic Interface Readily Accessible for Finite Elements) usando elementos finitos geometricamente exatos de viga, sujeitos a grandes deslocamentos e rotações finitas. Através da pesquisa, conclui-se que existe uma equivalência entre a aplicação da pressão interna como um carregamento distribuído dependente da curvatura do duto e a aplicação da pressão interna como uma força axial de compressão seguidora. Além disso, demonstra-se que o tipo de análise (estática e dinâmica) depende da natureza do sistema físico analisado. Com a ajuda de resultados apresentados em termos de pressão interna, os resultados clássicos sobre a influência das amplitudes das imperfeições e do atrito entre o duto e o solo são confirmados. Também é mostrado que as amplitudes das imperfeições analisadas desempenham uma maior influência nas configurações pós-críticas do duto do que o atrito.
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Tveråmo, Camilla. "Pipeline Walking of High Pressure/Temperature Flowlines." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for marin teknikk, 2013. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-22366.
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The offshore pipeline industry are facing more complex design challenges as the oiland gas industry moves into deeper water in search for hydrocarbons. One of thesechallenges are related to high pressure/high temperature pipelines subjected tofrequent start-up and shut-downs during its? lifetime. One consequence of this kindof load cycles is that the pipeline may move cycle wise and axially towards its? coldend, which may be detrimental for the end connection design. This phenomenonis termed pipeline walking.The SAFEBUCK Joint Industry Project was initiated in 2002 to assess the challengesconnected to pipeline walking, in addition to other related issues. Throughthis project several aspects affecting the walking behaviour have been established.These factors have, in this thesis, been addressed through a sensitivity analysis,where the seabed conditions ? hereby the equivalent friction factor ? the seabedslope, the effect of a global lateral buckle and the effect of a connected SCR havebeen included.The sensitivity study was performed on a pipeline modelled in SIMLA with 900beam elements, each connected with a spring to a seabed beam element. Thisoriginal case have here been labelled the base case. Four cases were analysed, wereone factor were changed throughout each of the cases. The pipeline was subjectedto a transient temperature profile in each case, provided by IKM Ocean Design,to simulate the heat transfer in a pipeline.For the seabed conditions case, the walk per load cycle increased with increasingequivalent friction factor up to a certain point, before the walk per load cycledecreased as the equivalent friction factor continued to increase. The seabed slopecase showed that the relationship between walk per cycle and increasing angle isapproximately linear. In addition it was established that when the seabed slope issteep enough, the pipeline will walk towards its? warm end. In the global lateralbuckle case on could observe that the effective axial friction force was relievedin the buckle, and that the walk per cycle increased as the length of the buckleincreased. When a steel catenary riser tension was introduced, the axial movementof the pipeline appeared to fluctuate around the walk per cycle values for the basecase.An analytical analysis was performed, however, the accordance between the numericaland analytical results was not as good as predicted. For this reason animprovement of the analytical model is suggested for further work. An other topicwhich is relevant for further work is an extension of the seabed conditions case toinclude mobilisation length. Additional sub-cases in the steel catenary riser case, aswell as creating a new case by combining the impact from several walking inducingfactors are other possible topics.
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Malerba, Diego Leonardo. "Failure Consequence Modelling of High Pressure Hydrocarbon Transmission Pipeline." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2018.
Find full textAbstract:
In the present century, one of the challenges of the energy industry is the integrity and security of pipeline systems, that constitute the most efficient and safest means of transportation for oil and gas hydrocarbons. To pursue this goal, owing to the complex nature of interacting process governing the discharge rate, the use of a rigorous CFD model is an essential pre-requisite for producing reliable pipeline failure consequence data.
For this reason, the Department of Chemical Engineering of The University College London (UCL) has developed a commercial software called PipeTech, which has been thought for predicting the outflow as well as the variation with space and time of the physical effects relative to all possible final scenarios following the release (i.e jet fire, pool fire, fireball, explosions) which can occur after a rupture along a pipe.
Over the years, several updating have been conducted on the computer software PipeTech, with the aim to improve its reliability. Nowadays, 84 versions of this software exist. This work is focused on the investigation about the last two subsequent versions of PipeTech (V83 and V84), in order to understand which of these is the most reliable in predicting the outflow data following a rupture at the end of a long Pipeline (FBR/orifice). In particular, this aim will be pursued by a systematic in-depth investigation about the release models used in the last two versions of this software and by using some experimental data. In the second part of this work, the most reliable version of PipeTech will be identified and used to make a full validation of the jet fire model employed in such software. In order to achieve this purpose, some experimental data as well as the commercial software Phast (V8.0) were applied.
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Dawson, Patricia Ann. "Gas release and the mathematical modelling of variable wavespeed pressure transients." Thesis, University of Leeds, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.329048.
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Jie, Hongen. "CFD modelling of transient two-phase flows for high pressure pipeline decompression." Thesis, Kingston University, 2013. http://eprints.kingston.ac.uk/28785/.
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A CFD model has been developed with the aim to predict transient two-phase flows for pipeline decompression. The arbitrary Lagrangian-Eulerian method was introduced to solve separately the convection terms from the other terms in a sub-cycled explicit manner using a sub-time step that is only a fraction of the main computational timestep, which can significantly simplify solution procedures and improve computational efficiency. The homogeneous equilibrium model (HEM) and homogeneous relaxation model (HRM) were employed to treat multi-component two phases as a continuous mixture based on the basic assumption of homogeneous flow. HEM assumes that the two phases are not only in thermodynamic equilibrium but also in mechanical equilibrium, namely the two phases share identical velocity, temperature and pressure and the rate of phase change is rapidly enough so that equilibrium is reached. However, the rate at which the phase change took place depends on interphase heat transfer and non-equilibrium effects. For the rapid pipeline decompression, the rates of interphase heat transfer are a limiting factor for phase change. In order to examine the non-equilibrium effect, the rate equation is introduced to evaluate the non-equilibrium generation of vapour or liquid phase by an approach of relaxation. HRM is proposed to deal with two-phase flows involved during pipeline decompression, and is extended for the multi-component dense fluid. The use of CFD allows the effect of pipe wall heat transfer and friction to be quantified. The wall heat transfer is considered through the implementation of a conjugate heat transfer model while the wall friction is computed using established empirical correlations. The Peng-Robinson-Stryjek- Vera equation of state (EOS), which is capable of predicting the real gas thermodynamic behaviour of mixture, has been implemented in addition to the Peng-Robinson EOS and Span-Wagner EOS, and the latter is used as a reference specifically for pure CO2. GERG-2004 is also employed for C02-rich mixture. Additionally, the liquid-vapour phase equilibrium of a multi-component two-phase mixture is determined by flash calculation. The current code with HEM is validated for natural gas, rich gas, liquefied petroleum gas, gaseous and dense phase C02 decompression against the available data of shock tube test. The decompression curve, which describes the propagation of the expansion wave immediately following a rupture, is obtained to be treated as the key input to the Battelle two-curve method which often used to determine the toughness required to arrest a running ductile fracture in a pipeline. Furthermore, the predictions of pressure and temperature time traces are compared with the results of British Gas shock tube tests, Botros's rich gas experiments, Isle of Grain full-scale experiments. The predictions show reasonably good agreement with the experimental data. Finally, C02 shock tube decompression is examined with the current model. Gaseous and dense phase C02 and C02-rich mixture shock tube tests are predicted. Predictions are compared with the available experimental data. The results show good agreement for C02 tests. The decompression behaviours of high pressure CO2 pipeline are studied and discussed. The effect of initial conditions and impurities on the decompression behaviour is investigated. Additionally, the effects of friction and heat transfer are evaluated for the gaseous and dense tests. Lastly, the non-equilibrium effect on the decompression behaviour is also evaluated for dense tests by employing the approach of HRM.
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Tiley, C. H. "Pressure transients in a ruptured gas pipeline with friction and thermal effects included." Thesis, City, University of London, 1989. http://openaccess.city.ac.uk/17971/.
Full textAbstract:
A theoretical model has been developed which can simulate a linebreak occurring in a gas pipeline. By assuming one-dimensional homogeneous gas flow and neglecting minor losses and changes in cross-sectional area of the pipe, three simultaneous non-linear partial differential equations were derived from first principles which mathematically model pressure transients in a non-perfect gas. A constant value steady-flow friction factor was used to calculate the frictional losses which was considered to be a reasonable approach since it would not be possible to account for all the variations in friction. The heat transfer into the pipe was accounted for using a constant value Stanton Number approach which again was an acceptable approximation considering the comparatively small effect that heat transfer has on the pressure transients. The equations were converted to ordinary differential equations using the Method of Characteristics and these were then solved numerically using a Taylor expansion. A novel feature of this project was the incorporation of a reduced grid size in the vicinity of the break allowing closer monitoring of the expansion waves in this area. Also included was a means of modelling flow reversal in the pipe which enabled situations with a non-zero initial flow rate to be simulated. A computer code solving the mathematical model was written in Fortran 77 for use on a Gould PN9005 mainframe computer. Both tabular and graphical output were produced which could then be compared with available experimental data. The experimental data that was selected for validation of the theoretical model included shock tube test results and some full size tests. Reasonable agreement was obtained between the theoretical and experimental results and any possible error sources were investigated.
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Iyalla, Ibiyekariwaripiribo. "Computational fluid dynamics modelling of pipeline on-bottom stability." Thesis, Robert Gordon University, 2017. http://hdl.handle.net/10059/2721.
Full textAbstract:
Subsea pipelines are subjected to wave and steady current loads which cause pipeline stability problems. Current knowledge and understanding on the pipeline on-bottom stability is based on the research programmes from the 1980’s such as the Pipeline Stability Design Project (PIPESTAB) and American Gas Association (AGA) in Joint Industry Project. These projects have mainly provided information regarding hydrodynamic loads on pipeline and soil resistance in isolation. In reality, the pipeline stability problem is much more complex involving hydrodynamic loadings, pipeline response, soil resistance, embedment and pipe-soil-fluid interaction. In this thesis Computational Fluid Dynamics (CFD) modelling is used to investigate and establish the interrelationship between fluid (hydrodynamics), pipe (subsea pipeline), and soil (seabed). The effect of soil types, soil resistance, soil porosity and soil unit weight on embedment was examined. The overall pipeline stability alongside pipeline diameter and weight and hydrodynamic effect on both soil (resulting in scouring) and pipeline was also investigated. The use of CFD provided a better understanding of the complex physical processes of fluid-pipe-soil interaction. The results show that the magnitude of passive resistance is on the average eight times that of lateral resistance. Thus passive resistance is of greater significance for subsea pipeline stability design hence the reason why Coulomb’s friction theory is considered as conservative for stability design analysis, as it ignores passive resistance and underestimates lateral resistance. Previous works (such as that carried out by Lyons and DNV) concluded that soil resistance should be determined by considering Coulomb’s friction based on lateral resistance and passive resistance due to pipeline embedment, but the significance of passive resistance in pipeline stability and its variation in sand and clay soils have not be established as shown in this thesis. The results for soil porosity show that increase in pipeline stability with increasing porosity is due to increased soil liquefaction which increases soil resistance. The pipe-soil interaction model by Wagner et al. established the effect of soil porosity on lateral soil resistance but did not attribute it to soil liquefaction. Results showed that the effect of pipeline diameter and weight vary with soil type; for sand, pipeline diameter showed a greater influence on embedment with a 110% increase in embedment (considering combined effect of diameter and weight) and a 65% decrease in embedment when normalised with diameter. While pipeline weight showed a greater influence on embedment in clay with a 410% increase. The work of Gao et al. did not completely establish the combined effect of pipeline diameter and weight and soil type on stability. Results also show that pipeline instability is due to a combination of pipeline displacement due to vortex shedding and scouring effect with increasing velocity. As scoring progresses, maximum embedment is reached at the point of highest velocity. The conclusion of this thesis is that designing for optimum subsea pipeline stability without adopting an overly conservative approach requires taking into consideration the following; combined effect of hydrodynamics of fluid flow on soil type and properties, and the pipeline, and the resultant scour effect leading to pipeline embedment. These results were validated against previous experimental and analytical work of Gao et al, Brennodden et al and Griffiths.
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Al-Jumaily, K. E. J. "Two phase flow pressure drop and void fraction studies in a large diameter horizontal pipeline." Thesis, University of Strathclyde, 1986. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.372062.
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Nosal, P. E. "Metallurgical investigation of hyperbaric welding at pressures to 250-bar for repairs to deep sea pipelines." Thesis, Cranfield University, 2001. http://dspace.lib.cranfield.ac.uk/handle/1826/11029.
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Saadawi, Abdunaser Ali. "Two phase flow metering and pressure loss through orifices and valves in a large diameter horizontal pipeline." Thesis, University of Strathclyde, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.248519.
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Pasha, Faiq Hussain 1959. "Optimal control of a valve to avoid column separation and minimize waterhammer pressures in a pipeline." Thesis, The University of Arizona, 1989. http://hdl.handle.net/10150/558105.
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Мягкий, Олександр Валерійович. "Підвищення завадостійкості теплової дефектоскопії багатошарових конструкцій та трубопроводів." Thesis, Харківський національний університет радіоелектроніки, 2018. http://repository.kpi.kharkov.ua/handle/KhPI-Press/40779.
Full textAbstract:
Дисертаційна робота на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.11.13 – прилади і методи контролю та визначення складу речовини. – Харківський національний університет радіоелектроніки, Харків, 2019.
Дисертація присвячена підвищенню завадостійкості теплової дефектоскопії багатошарових стільникових конструкцій і трубопроводів шляхом зниження завад в тепловому неруйнівному контролі як за рахунок вибору режиму контролю за критерієм максимуму відношення сигнал / завада, так і за допомогою подальшої комп'ютерної обробки отриманих експериментальних даних. Запропоновано теплофізичні моделі багатошарових стільникових конструкцій і трубопроводів. Розроблено програмний пакет "TermoPro_TFH_Statistic" і на його основі проведено чисельні експерименти по вибору режимів теплової дефектоскопії. Проведено ряд натурних і лабораторних експериментів з дослідження впливу завад на тепловий неруйнівний контроль. Розроблено ряд фільтрів, а також послідовність їх застосування для істотного зниження рівня завад при проведенні ТДС. Завдяки цьому підвищилась чутливість теплової дефектоскопії до виявлення дефектів типу "непроклей" в стільникових структурах – розмір порогового дефекту знижений з 6 мм до 3 мм, а достовірність їх виявлення зросла на 17-20%.The dissertation on the receipt of scientific degree of candidate of engineering sciences on speciality 05.11.13 – devices and methods of testing and materials composition determination. Kharkiv National University of Radio Electronics, Kharkiv, 2019. The dissertation is devoted to the question of immunity to interference improvement in the thermal non-destructive testing of multilayered honeycomb constructions and pipelines, both by the monitoring mode selection with the criterion of maximum signal-to-interference ratio, and by the further computer processing of obtained experimental data. Thermophysical models of multilayered honeycomb constructions are proposed. The software package "TermoPro_TFH_Statistic" was worked out and number of experiments at the thermal flaw detection modes selection were performed on its basis. A number of full-size and laboratory-scale experiments were conducted to investigate the interference effect on thermal non-destructive testing. A number of filters have been worked out, as well as the sequence of their use to significantly reduce the interference level during the thermal flaw detection. Due to this, the sensitivity of thermal defectoscopy to detection of defects of the "non-adhesive" type in honeycomb structures increased – the size of the threshold defect was decreased from 6mm to 3mm, and the reliability of their detection increased by 17-20%.
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Ткачук, Юрій Якович, Юрий Яковлевич Ткачук, Yurii Yakovych Tkachuk, Василь Олександрович Кугук, Василий Александрович Кугук, and Vasyl Oleksandrovych Kuhuk. "Использование стабилизаторов давления для обеспечения безаварийности трубопроводных систем." Thesis, Сумский государственный университет, 2013. http://essuir.sumdu.edu.ua/handle/123456789/31437.
Full textAbstract:
Очень часто в процессе эксплуатации незащищенных трубопроводных систем возникают волновые явления, которые включают в себя провалы давления, гидравлические удары, вынужденные колебания давления, автоколебания, резонансные явления, а также связанные с ними вибрационные процессы. Результатом подобных процессов становиться неизбежное разрушение трубопроводной системы.
При цитировании документа, используйте ссылку http://essuir.sumdu.edu.ua/handle/123456789/31437
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Мягкий, Олександр Валерійович. "Підвищення завадостійкості теплової дефектоскопії багатошарових конструкцій та трубопроводів." Thesis, Національний технічний університет "Харківський політехнічний інститут", 2019. http://repository.kpi.kharkov.ua/handle/KhPI-Press/40777.
Full textAbstract:
Дисертаційна робота на здобуття наукового ступеня кандидата технічних наук за спеціальністю 05.11.13 - прилади і методи контролю та визначення складу речовини. – Харківський національний університет радіоелектроніки, Харків, 2019.
Дисертація присвячена підвищенню завадостійкості теплової дефектоскопії багатошарових стільникових конструкцій і трубопроводів шляхом зниження завад в тепловому неруйнівному контролі як за рахунок вибору режиму контролю за критерієм максимуму відношення сигнал / завада, так і за допомогою подальшої комп'ютерної обробки отриманих експериментальних даних. Запропоновано теплофізичні моделі багатошарових стільникових конструкцій і трубопроводів. Розроблено програмний пакет "TermoPro_TFH_Statistic" і на його основі проведено чисельні експерименти по вибору режимів теплової дефектоскопії. Проведено ряд натурних і лабораторних експериментів з дослідження впливу завад на тепловий неруйнівний контроль. Розроблено ряд фільтрів, а також послідовність їх застосування для істотного зниження рівня завад при проведенні ТДС. Завдяки цьому підвищилась чутливість теплової дефектоскопії до виявлення дефектів типу "непроклей" в стільникових структурах – розмір порогового дефекту знижений з 6 мм до 3 мм, а достовірність їх виявлення зросла на 17 -20%.The dissertation on the receipt of scientific degree of candidate of engineering sciences on speciality 05.11.13 – devices and methods of testing and materials composition determination. Kharkiv National University of Radio Electronics, Kharkiv, 2019. The dissertation is devoted to the question of immunity to interference improvement in the thermal non-destructive testing of multilayered honeycomb constructions and pipelines, both by the monitoring mode selection with the criterion of maximum signal-to-interference ratio, and by the further computer processing of obtained experimental data. Thermophysical models of multilayered honeycomb constructions are proposed. The software package "TermoPro_TFH_Statistic" was worked out and number of experiments at the thermal flaw detection modes selection were performed on its basis. A number of full-size and laboratory-scale experiments were conducted to investigate the interference effect on thermal non-destructive testing. A number of filters have been worked out, as well as the sequence of their use to significantly reduce the interference level during the thermal flaw detection. Due to this, the sensitivity of thermal defectoscopy to detection of defects of the "non-adhesive" type in honeycomb structures increased – the size of the threshold defect was decreased from 6mm to 3mm, and the reliability of their detection increased by 17-20%.
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Malde, Rahil. "An analysis of leakage parameters of individual leaks on a pressure pipeline through the development and application of a standard procedure." Master's thesis, University of Cape Town, 2015. http://hdl.handle.net/11427/13726.
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Water is a vital and scarce resource. Providing a sustainable and efficient means of transporting water is essential to the wellbeing of humankind. Most water distribution systems worldwide are ageing and deteriorating, as a result, leakage is a common problem. Modern water distribution systems use a variety of methods to minimise leakage, one of them is pressure management. However, the relationship between leakage and pressure is a complex one. The goals of this study were to develop a standard experimental procedure to determine the leakage parameters of a pipe with an individual leak, and to test a series of pipes using the newly developed procedure to determine their leakage parameters. There have been numerous experimental investigations into the leakage parameters; however, these investigations have variation in their methodologies. Therefore, developing a standard procedure will provide a consistent method for the accurate determination of the leakage parameters. Leakage parameters are important as they help to improve the understanding of the relationship between leakage and pressure. They are also important for use in the two main equations used to relate leakage and pressure, i.e. the N1 equation and the FAVAD equation. The determination of a variety of leakage parameters will help to determine whether both equations explain the behaviour of a variety of pipe samples, and which equation is better suited for use in leakage prediction.
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Грабовський, Р. С. "Наукові основи оцінювання безпечної роботи та довговічності нафтогазопроводів тривалої експлуатації за параметрами їх дефектності." Thesis, Івано-Франківський національний технічний університет нафти і газу, 2012. http://elar.nung.edu.ua/handle/123456789/1847.
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Дисертація присвячена проблемам розроблення критеріїв оцінювання безпечної роботи та здійснення прогнозних розрахункових оцінок міцності та залишкового ресурсу тривало експлуатованих нафтогазопроводів із наявними дефектами, що є базисом для експертних висновків про можливість їх подальшої безпечної роботи або виведення з експлуатації.
На основі проведених досліджень поверхневого тріщиноутворення при корозійно-втомній пошкоджуваності сталей для нафтогазопроводів отримано критеріальне співвідношення між довжиною поверхневої тріщини, характеристичним значенням прикладеного напруження та параметрами електрохімічного розчинення металу, а також отримано вираз для визначення період до зародження поверхневої корозійно-втомної тріщини.
Одержано нові експериментальні дані про зміну характеристик циклічної тріщиностійкості трубопровідних сталей залежно від сумісного впливу часу експлуатації та корозійних середовищ.
Запропоновано розрахункову методику та алгоритм її чисельної реалізації для оцінювання специфіки розвитку тріщин у стінках трубопроводів залежно від стану металу та оточуючого корозійного середовища, на основі якої досліджено кінетику поширення тріщиноподібних дефектів різної форми при їх розвитку в стінці труби за втомним та корозійно-втомним механізмом.
Запропоновано критерії безпечної експлуатації та оцінювання довговічності тривало експлуатованих нафтогазопроводів на підставі концепції порогового дефекту та умов потенційного катастрофічного руйнування дефектної труби.
Розроблено методику визначення руйнівного тиску у нафтогазопроводах з корозійно-втомними тріщиноподібними дефектами, яка враховує чинник потенційної можливості субкритичного росту тріщини за втомним механізмом.
Запропоновані підходи дозволили оцінити залишковий ресурс лінійних ділянок деяких дефектних нафтогазопроводів із урахуванням деградації властивостей металу під довготривалою дією експлуатаційних чинників середовища.The dissertation focuses on problems of development of criteria for assessment of safe operation and forecasting of strength and residual lifetime of the long-term exploited oil-and-gas pipelines with defects for making of the expert conclusions on possibility of their further safe work or decommissioning. Based on studies of surface corrosion fatigue cracking of steels for oil-and-gas pipelines, the criterion relation between surface crack length, characteristic value of applied cyclic stress and parameters of the electrochemical dissolution of metal was derived, On this ground the formula for calculation of the period of nucleation of surface corrosion fatigue crack has been proposed and verified. The new experimental data on the corrosion fatigue crack growth behaviour of pipeline steels were received and analysed depending on the operation time and the presence of corrosion environments. The calculation method and algorithm of its numerical realisation for assessment of the specificity of fatigue crack growth in the wall of pipe was developed and on this base the kinetics of crack propagation was determined for defects of different shape under fatigue and corrosion fatigue conditions. The criteria of safe operation and for assessment of residual lifetime were proposed on the basis of concept of threshold defect and conditions of potential catastrophic failure of defective pipe. The method for determination of the failure pressure in the defected oil-and-gas pipelines was developed with taking into account the potential possibility of subcritical crack growth under fatigue mechanism. The developed methods were used for fracture risk assessment and residual lifetime evaluation of some linear sections of the long-term exploited oil-and-gas pipelines with defects.
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Hettiaratchi, Kaushika. "A comparison between the pressure gradients in vertical and horizontal pneumatic conveying, with an investigation into the effect of pipeline bore in vertical conveying." Thesis, University of Greenwich, 2006. http://gala.gre.ac.uk/6190/.
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This study was initiated by the need to improve current techniques used in the design of pneumatic conveying systems. At present, the commonly used method to predict the pressure drop in a vertical pipeline in a pneumatic conveying system is to obtain the pressure gradient in a horizontal for the identical conveying conditions and double the pressure gradient in the horizontal pipeline to give the pressure gradient in the vertical pipeline. In addition, scaling for pipeline bore in vertical pipelines is simply undertaken by considering the change in cross-sectional area. This is another area where sufficient investigation has not been undertaken. Therefore, as part of remit of this research study into improving current design techniques, an investigation into the effect of pipeline bore in vertical conveying would also be undertaken. This thesis documents the systematic approach that was used in order to produce some usable models that may be used in improving the understanding and design of pneumatic conveying systems. The models produced were based on data obtained by testing a range of products in an industrial scale pneumatic conveying test facility. The experimental data that was obtained from the pneumatic conveying tests form the basis of the ensuing analysis. The basic experimental data, which is primarily in the form of pressure gradient data for pneumatic conveying in horizontal and vertical pipelines, is explained in detail, along with the subsequent analysis of the data.
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Phan, Van Trung. "Modelling of the in service behaviour of passive insulated structures for deep sea offshore applications." Thesis, Brest, 2012. http://www.theses.fr/2012BRES0098/document.
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L’étude se situe dans le cadre de la recherche de gains de performance de structures d’isolations passives pour l’offshore profond. Le travail proposé a pour support des analyses expérimentales et numériques de tubes revêtus par des matériaux isolants utilisés en eau profonde pour transporter du fluide chaud. Le raboutage des tubes en acier, préalablement revêtus en atelier, nécessite un dégagement du revêtement aux extrémités pour réaliser l'opération d'assemblage (généralement par soudure). La partie dégagée est ensuite recouverte par un nouveau matériau pouvant être appliqué sur site. Ainsi l’isolation de cette partie du tube (Field Joint), qui est soumise à des chargements thermomécaniques en service, doit être optimisée pour assurer une durée de vie compatible avec les contraintes de l’exploitation offshore en eau profonde. Le travail comporte principalement quatre parties : - la modélisation du comportement thermique pour analyser l’évolution en temps et en espace de la température du matériau au cours de la fabrication, de la pose et en service sachant que pour les matériaux d’isolation le comportement mécanique est fortement dépendant de la température,- une partie expérimentale pour l’analyse du comportement des matériaux isolants en fonction de la température et en fonction de la pression hydrostatique qui est le principal chargement mécanique de ces structures en service,- la modélisation du comportement mécanique des isolants,- et une partie modélisation et simulation du comportement en service d'assemblages multi-matériaux de type industriel, avec prise en compte du comportement non-linéaire des constituantsUltra deep offshore oil exploitation presents new challenges to offshore engineering and operating companies. Such applications require the use of pipelines with an efficient thermal protection. Passive insulation materials are commonly used to guarantee the thermal performance of the pipes, and syntactic foams are now the preferred material for this application. The mechanical behaviour of such insulation materials is quite complex, associating time-dependent behaviour of polymers with damage behaviour of glass microspheres. In order to allow an optimisation of such systems, while ensuring in-service durability, accurate numerical models of insulation materials are thus required. During the service life in deep water, hydrostatic pressure is the most important mechanical loading of the pipeline, so this study aims to describe the mechanical behaviour of the material under such loading. Using a hyperbaric chamber, the analysis of the evolution of the volumetric strain with time, with respect to the temperature, under different time-evolutions of the applied hydrostatic pressure is presented in this paper. Such experimental results associated with the mechanical response of the material under uniaxial tensile creep tests, allow the development of a thermo-mechanical model, so that representative loadings can be analysed
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Toro, Rafael Jose Niño. "Pressão de ruptura de dutos contendo defeitos de corrosão." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/18/18134/tde-26032015-101325/.
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Uma grande variedade de modelos é utilizada para estimar a pressão de ruptura de dutos contendo defeitos de corrosão. O presente trabalho tem como objetivo estudar a precisão dos modelos mais comuns e avaliar a pressão de ruptura de dutos submetidos à corrosão. Os modelos avaliados são: ASME B31G, ASME B31G modificado, DNV RP F101 e PCORRC. O estudo é baseado em mais de 400 resultados de ensaios de ruptura em dutos corroídos, todos coletados da literatura. A base de dados contem defeitos de corrosão reais e artificiais. Uma análise estatística foi realizada para a variável erro de modelo. Uma análise de regressão não-linear foi realizada para investigar os efeitos da variável erro de modelo, das variáveis mais relevantes, como profundidade e comprimento do defeito, e tensão de ruptura do aço. Uma análise de confiabilidade foi realizada a partir das estatísticas obtidas da variável erro de modelo, sendo estimado o índice de confiabilidade e a probabilidade de falha do duto com defeitos de corrosão, através do método iterativo de primeira ordem, denominado FORM (First Order Reliability Method). Nesta análise avaliou-se a evolução da probabilidade de falha com o aumento da profundidade do defeito, bem como foram identificadas as variáveis aleatórias mais importantes na falha do duto. O estudo pode ajudar aos operadores a eleger qual modelo utilizar em análises de risco, proporcionando mais segurança às operações dutoviárias.A variety of models exist to estimate burst pressures of pipelines containing corrosion defects. The objective of this work is to study the accuracy of some of the most popular empirical burst pressure models. The study addresses the models: ASME B31G, ASME B31G Modified, DNV RP-F101 and PCORRC. The investigation is based on over 400 burst test results, all collected from the literature, containing both real and artificial corrosion defects. A statistical analysis is performed for assessing the accuracy of semi-empirical models by using a model error variable. A non-linear regression analysis is performed to identify the influence, on model errors, of the most relevant variables, such as defect depth and length and steels rupture tension. A reliability analysis was carried out, using model error statistics developed herein, in order to evaluate reliability index and probability of failure of pipelines containing corrosion defects, through the iterative first order reliability method, or FORM - First Order Reliability Method. The evolution of failure probabilities, with increasing defect depth, was investigated. The most relevant random variables were identified. The study can help operators choose a proper empirical model to use in their risk analysis, leading to greater safety in pipeline operations.
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Vlasák, Bohdan. "Ztráty v potrubí průtokem směsných substrátů." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2009. http://www.nusl.cz/ntk/nusl-228576.
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Introductory part of this thesis is aimed on theoretical description, principle and building of biogas stations, which require solution of many different problems. A specific group of the problems concern transport of mixed substrates of different concentrations both in and outside the area of biogas station. A major part of the substrate transport is done by pumping it in pressure pipeline. Experimental work consists of design and description of a measuring circuit. Graphic characteristics for water and gas loss levels are drawn from the measured readings. Multiples of pressure losses by flowage of substrates with different levels of dry basis are graphically expressed with a help of correction coefficients.
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Kolář, Tomáš. "Studie odkanalizování vybrané obce." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2018. http://www.nusl.cz/ntk/nusl-371960.
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The subject of this diploma thesis is a study of two variants of sewer network of Cetechovice. Variant solutions include the use of existing segments supplemented by new gravitational or pressure sections. The proposed variant solutions are then economically assessed.
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Suchý, Václav. "Výpočet tlakových ztrát spalinových kanálů s využitím matematického modelování." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2018. http://www.nusl.cz/ntk/nusl-378738.
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This diploma thesis deals with the calculation of pressure losses in the flue gas ducts. First part of this work describes properties of flue gas and flow dynamics. Part of the theoretical analysis was detailed study of pipeline elements with emphasis on the reasons for the existence of pressure loss in the flow, calculations of the resistance coefficients and possible methods of reducing the losses. In the practical part, a model of the pressure loss calculation of the existing flue gas line installed in the incineration plant was created. At the end of the thesis a proposal for optimization of this route was made with emphasis on the reduction of the overall pressure loss. By optimization the pressure drop of the specified route was reduced from 3581 Pa to 2647 Pa, i.e by 26% and the required power input of the fan was reduced from 225 kW to 166,5 kW.
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Klíma, Aleš. "Odkanalizování obce do 2 tisíc obyvatel." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2013. http://www.nusl.cz/ntk/nusl-226151.
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In this thesis I deal with the drainage of Hněvošice village (the village up to 2000 inhabitants). I made a technical and economic evaluation of three possible drainage systems (gravity sewers, vacuum sewers, pressure sewers). After assessing I have chosen one of them, the gravity sewers. Then I made a complete design of the sewers including design sewerage treatment plant.
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Запухляк, В. Б. "Удосконалення техніки і технології проведення робіт з реконструкції і ремонту трубопроводів." Thesis, Івано-Франківський національний технічний університет нафти і газу, 2011. http://elar.nung.edu.ua/handle/123456789/1956.
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Дисертацію присвячено удосконаленню технічних засобів і технологій проведення безвогневого врізання в діючий газонафтопровід під тиском на етапах реконструкції та ремонту. Досліджено і проаналізовано процес формування температурного поля від колового руху зварювальної дуги як джерела тепла в стінці діючого трубопроводу. Проведені експериментальні дослідження залежності механічних характеристик трубних сталей від температури. На основі проведених теоретичних і експериментальних досліджень розроблені рекомендації з удосконалення безвогневого методу врізання в діючий трубопровід під тиском. Результати промислових випробувань підтверджують високу ефективність проведених досліджень і розробок. Створено і затверджено галузеву методику «Типові розрахунки показників надійності систем газонафтопостачання»The thesis is devoted to the improvement of technical means and technologies of hot tapping into a running oil and gas pipeline under the pressure at the stages of reconstruction and maintenance. It is developed and analyzed the process of forming of temperature field from a circular motion of welding arc as a heat source in the wall of running pipeline. It is conducted the experimental research of mechanical characteristic dependence of pipe steel on temperature. On the basis of the conducted theoretical and experimental researches, the recommendation on the improvement of hot tapping into a running pipeline under the pressure is made. Industrial testing results confirm high effectiveness of the conducted research and developments. It is developed and approved an industrial strategy, named “Typical Calculations of the Reliability Index of Oil and Gas Supply Systems”.