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Unpacking the Discipline Gap: Referral Categories and School-Wide Positive Behavior Interventions and SupportsBarclay, Christopher Michael 14 October 2015 (has links)
Despite decades of efforts to racially integrate schools and the recent accountability movement, U.S. students’ access to equitable education remains elusive. Research demonstrates that discipline procedures disproportionately remove racial minority students from the classroom, creating a “discipline gap.” Racial disparities in discrete disciplinary infraction types (e.g., disruption, aggression) have shown nuanced patterns across groups and school levels. Moreover, the relationship between school-wide positive behavior interventions and supports (SWPBIS) – a framework for promoting positive behavior and preventing conflict – and the discipline gap is unclear. This investigation explored racial/ethnic disparities per infraction type (e.g. disruption, verbal abuse) and the relationship of SWPBIS implementation fidelity to these referrals using multilevel logistic regression analyses. Participants were 40 elementary schools receiving PBIS technical assistance and the 24,512 students served by the schools. Findings of disciplinary disparities largely were consistent with previous studies with similar methods. Compared to White peers, Black students were overrepresented in office discipline referrals (ODRs) across all infraction types while Hispanic students were underrepresented in Aggression referrals and other racial/ethnic minority students were underrepresented in Miscellaneous referrals. SWPBIS implementation fidelity demonstrated a significant negative relationship with the overall ODR rate and was significantly related to infractions for Aggression; however, no evidence was produced to support the notion that SWPBIS produces more equitable discipline practices. Implications for the research and practice of culturally responsive behavior supports are discussed.
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Predictions of explosions and fires of natural gas/hydrogen mixtures for hazard assessmentMumby, Christopher January 2010 (has links)
The work presented in this thesis was undertaken as part of the safety work package of the NATURALHY project which was an integrated project funded by the European Commission (EC) within the sixth framework programme. The purpose of the NATURALHY project was to investigate the feasibility of using existing natural gas infrastructure to assist a transition to a hydrogen based economy by transporting hydrogen from its place of production to its place of use as a mixture of natural gas and hydrogen. The hydrogen can then be extracted from the mixture for use in fuel cells or the mixture used directly in conventional combustion devices. The research presented in this thesis focused on predicting the consequences of explosions and fires involving natural gas and hydrogen mixtures, using engineering type mathematical models typical of those used by the gas industry for risk assessment purposes. The first part of the thesis concentrated on modifying existing models that had been developed to predict confined vented and unconfined vapour cloud explosions involving natural gas. Three geometries were studied: a confined vented enclosure, an unconfined cubical region of congestion and an unconfined high aspect ratio region of congestion. The modifications made to the models were aimed at accounting for the different characteristics of a natural gas/hydrogen mixture compared to natural gas. Experimental data for the laminar burning velocity of methane/hydrogen mixtures was obtained within the safety work package. For practical reasons, this experimental work was carried at an elevated temperature. Predictions from kinetic modelling were employed to convert this information for use in models predicting explosions at ambient temperature. For confined vented explosions a model developed by Shell (SCOPE) was used and modified by adding new laminar burning velocity and Markstein number data relevant to the gas compositions studied. For vapour cloud explosions in a cubical region of congestion, two models were used. The first model was developed by Shell (CAM2), and was applied using the new laminar burning velocity and other composition specific properties. The second model was based on a model provided by GL Services and was modified by generalising the flame speed model so that any natural gas/hydrogen mixture could be simulated. For vapour cloud explosions in an unconfined high aspect ratio region of congestion, a model from GL Services was used. Modifications were made to the modelling of flame speed so that it could be applied to different fuel compositions, equivalence ratios and the initial flame speed entering the congested region. Predictions from the modified explosion models were compared with large scale experimental data obtained within the safety work package. Generally, (apart from where continuously accelerating flames were produced), satisfactory agreement was achieved. This demonstrated that the modified models could be used, in many cases, for risk assessment purposes for explosions involving natural gas/hydrogen mixtures. The second part of thesis concentrated on predicting the incident thermal radiation from high pressure jet fires and pipelines fires involving natural gas/hydrogen mixtures. The approach taken was to modify existing models, developed for natural gas. For jet fires three models were used. Fuel specific input parameters were derived and the predictions of flame length and incident radiation compared with large scale experimental data. For pipeline fires a model was developed using a multi-point source approach for the radiation emitted by the fire and a correlation for flame length. Again predictions were compared with large scale experimental data. For both types of fire, satisfactory predictions of the flame length and incident radiation were obtained for natural gas and mixtures of natural gas and hydrogen containing approximately 25% hydrogen.
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Vamzdyno nuogulų tyrimas ir apibūdinimas / The research and characterization of pipeline scalesVerikienė, Vaida 22 June 2010 (has links)
Baigiamajame magistro darbe „Vamzdyno nuogulų tyrimas ir apibūdinimas“, apžvelgus mokslinės literatūros šaltinius, apibūdintos ant vamzdžių vidinių sienelių susidarančios nuogulos, kurių sudėtyje vyrauja geležies junginiai. Nagrinėjama, kokią įtaką vandens kokybei turi ant skirtingų medžiagų vamzdžių vidinių sienelių susidariusios nuogulos. Aptariama, kokios dėl nuogulų susidarymo iškyla problemos vandentiekio sistemoje.
Vilniaus Gedimino technikos universiteto Vandentvarkos katedros laboratorijoje buvo atliktas eksperimentas, sumontavus du eksperimentinius stendus. Juos sudarė skirtingų medžiagų (PE, cinkuoto plieno ir seno plieno) vamzdynų sistemos, kuriomis cirkuliavo skirtingos kokybės vanduo. Buvo nustatyta kiekybinė ir kokybinė nuogulų sudėtis. Kiekybinė sudėtis apibūdinta ChDS pokyčiu, esant skirtingai vandens išbuvimo trukmei vamzdyne. Kokybinę sudėtį apibūdina geležies, mangano junginių, amonio jonų, nitritų ir nitratų koncentracijos vandenyje. Tai pat nustatyta vamzdyno nuogulų granuliometrinė sudėtis. Atlikus tyrimus paaiškėjo, kad bendrosios geležies koncentracija mažiausia buvo PE, o didžiausia – seno plieno vamzdyno mėginiuose. PE vamzdyne mangano koncentracija didėjo ilgėjant vandens užsistovėjimo trukmei. Amonio jonų, nitritų ir nitratų kiekiai mėginiuose neviršijo higienos normų. PE vamzdynų nuogulų ChDS rodikliai buvo mažiausi abiejuose stenduose. Palyginus eksperimentinių stendų nuogulų mėginių rezultatus, paaiškėjo, kad ChDS reikšmės priklauso nuo vandens... [toliau žr. visą tekstą] / In the Master‘s Thesis "The research and characterization of pipeline scales" the literature review of scientific sources was described pipeline scales which contains predominantly iron compounds. The impact of water quality on the pipeline scales was investigated. Negative impact of the formation of pipeline scales on water distribution system was analysed.
Experimental investigation was carried out in the laboratory scaled equipment at Water Management Department of VGTU. Experimental pipelines consist of different materials (galvanized steel, old steel and polyethylene (PE)) pipe system with circulated different water quality. The quantitative and qualitative composition of the scales was measured. The quantitative composition was described of the change of COD under different water age in to the different pipelines. The qualitative composition was described by iron, manganese compounds, ammonium, nitrite and nitrate concentrations in water. It was also set the particle size content of pipeline scales.
Results showed that the lowest iron concentration was in PE pipe samples and the highest in an old steel pipe samples. The concentration of manganese increased with increasing duration of water age in PE pipe. Ammonium ions, nitrite and nitrate levels didn't exceed the requirements of hygiene norm. The lowest COD rates were in PE pipe scales in both laboratory scaled equipments. It was found that COD values depend on the quality of water that circulated in pipeline. It was... [to full text]
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Des réseaux de processus cyclo-statiques à la génération de code pour le pipeline multi-dimensionnel / From Cyclo-Static Process Networks to Code Generation for Multidimensional Software PipeliningFellahi, Mohammed 22 April 2011 (has links)
Les applications de flux de données sont des cibles importantes de l’optimisation de programme en raison de leur haute exigence de calcul et la diversité de leurs domaines d’application: communication, systèmes embarqués, multimédia, etc. L’un des problèmes les plus importants et difficiles dans la conception des langages de programmation destinés à ce genre d’applications est comment les ordonnancer à grain fin à fin d’exploiter les ressources disponibles de la machine.Dans cette thèse on propose un "framework" pour l’ordonnancement à grain fin des applications de flux de données et des boucles imbriquées en général. Premièrement on essaye de paralléliser le nombre maximum de boucles en appliquant le pipeline logiciel. Après on merge le prologue et l’épilogue de chaque boucle (phase) parallélisée pour éviter l’augmentation de la taille du code. Ce processus est un pipeline multidimensionnel, quelques occurrences (ou instructions) sont décalées par des iterations de la boucle interne et d’autres occurrences (instructions) par des iterationsde la boucle externe. Les expériences montrent que l’application de cette technique permet l’amélioration des performances, extraction du parallélisme sans augmenter la taille du code, à la fois dans le cas des applications de flux des donnée et des boucles imbriquées en général. / Applications based on streams, ordered sequences of data values, are important targets of program optimization because of their high computational requirements and the diversity of their application domains: communication, embedded systems, multimedia, etc. One of the most important and difficult problems in special purpose stream language design and implementation is how to schedule these applications in a fine-grain way to exploit available machine resources In this thesis we propose a framework for fine-grain scheduling of streaming applications and nested loops in general. First, we try to pipeline steady state phases (inner loops), by finding the repeated kernel pattern, and executing actor occurrences in parallel as much as possible. Then we merge the kernel prolog and epilog of pipelined phases to move them out of the outer loop. Merging the kernel prolog and epilog means that we shift acotor occurrences, or instructions, from one phase iteration to another and from one outer loop iteration to another, a multidimensional shifting. Experimental shows that our framwork can imporove perfomance, prallelism extraction without increasing the code size, in streaming applications and nested loops in general.
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Computational Pipeline for Human Transcriptome Quantification Using RNA-seq DataXu, Guorong 04 August 2011 (has links)
The main theme of this thesis research is concerned with developing a computational pipeline for processing Next-generation RNA sequencing (RNA-seq) data. RNA-seq experiments generate tens of millions of short reads for each DNA/RNA sample. The alignment of a large volume of short reads to a reference genome is a key step in NGS data analysis. Although storing alignment information in the Sequence Alignment/Map (SAM) or Binary SAM (BAM) format is now standard, biomedical researchers still have difficulty accessing useful information. In order to assist biomedical researchers to conveniently access essential information from NGS data files in SAM/BAM format, we have developed a Graphical User Interface (GUI) software tool named SAMMate to pipeline human transcriptome quantification. SAMMate allows researchers to easily process NGS data files in SAM/BAM format and is compatible with both single-end and paired-end sequencing technologies. It also allows researchers to accurately calculate gene expression abundance scores.
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[en] DYNAMIC BEHAVIOR OF BURIED PIPES: METHODOLOGY AND COMPUTATIONAL IMPLEMENTATION / [pt] COMPORTAMENTO DINÂMICO DE DUTOS ENTERRADOS: METODOLOGIA E IMPLEMENTAÇÃO COMPUTACIONALIGOR EDUARDO OTINIANO MEJIA 31 March 2009 (has links)
[pt] Neste trabalho apresenta-se uma metodologia de análise do
comportamento mecânico de dutos enterrados usados no
transporte de gás e outros fluidos sujeitos
a cargas dinâmicas. Em especial são considerados
carregamentos provocados por sismos. Emprega-se uma
modelagem em elementos finitos com base em uma
discretização com elementos especiais de viga para modelar
o duto. Não linearidades geométricas e do material são
consideradas numa formulação Lagrangeana total. As equações
de equilíbrio são formuladas a partir do principio
dos trabalhos virtuais, segundo as componentes de tensão e
deformação no elemento viga-duto. A técnica do Módulo
Reduzido de Integração Direta (RMDI) é empregada na qual se
incorpora o comportamento elasto-plástico do material.
Esta abordagem exclui da análise os efeitos do enrugamento
nas paredes do duto. As matrizes para resolução por
elementos finitos dessas equações são derivadas.
Nessa metodologia os efeitos da interação solo-duto são
incorporados. O solo é modelado através de elementos
bidimensionais considerando um modelo constitutivo Linear-
Equivalente, acoplados ao duto por meio de elementos de
interface localizados entre o duto e o solo. Finalmente são
considerados contornos artificiais amortecidos para
possibilitar a representação do problema através de
um trecho finito. Foram usados para as análises históricos
de acelerações do tipo sismo, entre estes o sismo ocorrido
em Pisco-Perú no ano 2007. Desenvolve-se
um programa para computador segundo a metodologia
apresentada. Finalmente
são estudados alguns exemplos com o objetivo de avaliar
numericamente os resultados da análise obtidos e formular
algumas conclusões sobre o
comportamento de dutos enterrados sujeitos a cargas
dinâmicas. / [en] This work presents a numerical methodology for the analysis
of buried pipes employed by the transport of oil and gas
subject to dynamic loads. Emphasis is given to seismic
loads. A finite element model based on a special class of
beam element for the pipe representation is employed. Both
geometric and material nonlinearities are considered in a
total Lagrangean formulation. The equilibrium
equations are formulated based on the virtual work
principle considering the stress and deformation components
of the beam-pipe element. The Reduced Modulus
Direct Integration (RMDI) technique is employed by which
the elasto-plastic material behavior is incorporated. This
technique excludes from the analysis the
local buckling effects of the pipe walls. The corresponding
finite element matrices for this element are obtained. In
this methodology the effects of the constant
internal pressure as well as the soil-pipe interaction are
included. The soil is modeled through two-dimensional
elements with material behavior described
through a linear equivalent model. Interface elements
couple beam-pipe elements with soil elements and account
for soil-pipe interaction. Finally silent boundary
elements are incorporated to the model to reproduce the
semi-infinite boundary conditions in the finite size model.
Distributed loads are considered constant with
respect to the global axis. Acceleration histories are
applied to simulate seismic dynamic loads among which the
acceleration histories of the earthquake which
occurred in Pisco-Perú in 2007. A finite element computer
code is developed according to the methodology presented.
Some examples are studied with the objective to evaluate
numerically the analysis results and to formulate some
conclusions to the behavior of buried pipes subject to
seismic loads.
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[en] NUMERICAL SIMULATION OF TWOPHASE SLUG FLOW IN HORIZONTAL AND NEARLY HORIZONTAL PIPES / [pt] SIMULAÇÃO NUMÉRICA DE ESCOAMENTOS BIFÁSICOS NO REGIME DE GOLFADAS EM TUBULAÇÕES HORIZONTAIS E LEVEMENTE INCLINADASJOAO NEUENSCHWANDER ESCOSTEGUY CARNEIRO 25 April 2006 (has links)
[pt] Escoamentos bifásicos no regime de golfadas são
caracterizados pela
alternância de pacotes de líquido e grandes bolhas de gás
na tubulação, sendo
associados a altas perdas de carga, além de trazer uma
indesejada intermitência
aos escoamentos. O desenvolvimento do regime de golfadas
em tubulações
horizontais se dá a partir do escoamento estratificado em
decorrência de dois
fatores: do crescimento natural de pequenas perturbações
(por um mecanismo de
instabilidade do tipo Kelvin-Helmholtz) ou devido à
acumulação de líquido
causada por mudanças de inclinação no perfil do duto. O
presente trabalho
consiste da simulação numérica do surgimento das golfadas
em ambas as
situações descritas acima, assim como do subseqüente
desenvolvimento do
escoamento neste padrão para um regime estatisticamente
permanente. A
previsão do escoamento é obtida utilizando-se uma
formulação unidimensional
baseada no Modelo de Dois Fluidos. Parâmetros médios das
golfadas
(comprimento, velocidade e freqüência) são comparados com
estudos numéricos
e experimentais da literatura, obtendo-se uma concordância
bastante satisfatória,
especialmente dada a simplicidade de uma formulação
unidimensional. / [en] Slug flow is a two-phase flow pattern which is
characterized by the
periodic presence of packs of liquid and long bubbles in
the tube, associated with
high pressure-drops and an often undesired intermittency
in the system. The
development of the slug pattern in horizontal pipes is
caused by two reasons: the
natural growth of small disturbancies at the interface (by
a Kelvin-Helmholtz
instability mechanism) or the liquid accumulation at
valleys of hilly terrain
pipelines with sections of different inclinations. The
present work consists of the
numerical simulation of the onset of slugging in both
situations, as well as the
subsequent development of statistically steady slug flow
in the pipe. The
prediction of the flow is obtained through a one-
dimensional formulation based
on the Two-Fluid Model. Averaged slug parameters (length,
velocity and
frequency) are compared with previous numerical studies
and experimental
correlations avaiable in the literature, and a very
satisfactrory agreement is
obtained, specially given the simplicity of a one
dimensional formulation.
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Conflitos e contratos: a Petrobras, o nacionalismo boliviano e a interdepedência do gás natural (2002-2010) / Conflicts and contracts: Petrobras, Bolivian nationalism and interdependence of natural gas (2002-2010)Fuser, Igor 20 September 2011 (has links)
A nacionalização dos hidrocarbonetos pelo presidente boliviano Evo Morales, em maio de 2006, provocou a mais séria crise na política externa brasileira durante o primeiro mandato presidencial de Lula. A decisão prejudicou os interesses da Petrobras, na época a maior empresa instalada na Bolívia, com presença em todos os ramos da atividade petroleira. O conflito foi amplificado pela existência de uma relação de interdependência entre os dois países com base no gasoduto de 3.150 quilômetros, que transporta quase a metade do gás natural consumido pela indústria no Brasil. Com a nacionalização sem expropriação, segundo a fórmula adotada por Morales, as empresas estrangeiras foram autorizadas a permanecer na Bolívia, mas tiveram de renegociar seus contratos, aceitando a ampliação da receita fiscal (government take) obtida pelo governo a partir da produção petroleira. Essa decisão do governo boliviano expôs as contradições da política do Brasil para a América do Sul. Lula, pressionado pela oposição conservadora, intercedeu em defesa dos lucros da Petrobras, mas ao mesmo tempo reconheceu a nacionalização como expressão do direito soberano da Bolívia em legislar sobre seus próprios recursos naturais, abstendo-se de represálias. A tese explora a ambigüidade do comportamento regional do Brasil, que tenta conciliar um discurso de solidariedade em relação aos vizinhos menos desenvolvidos com uma política de expansão das empresas brasileiras e de proteção dos investimentos no exterior. O conflito em torno do gás boliviano abalou os planos brasileiros de liderança regional sul-americana e tornou mais difícil a integração energética, uma das prioridades da política externa de Lula. / The nationalization of hidrocarbons by Bolivian president Evo Morales, in May 2006, has provocated the most serious crisis in Brazilian foreign policy during Lulas first presidential term. The decision has damaged the interests of Petrobras, then the biggest corporation in Bolivia, operating in all branches of oil activities. The conflict was amplified by the interdependent relationship between the two countries through a 3.150 kilometers gasoduct, which carries almost half the natural gas consumed by Brazilian industry. By nationalization without expropriation, according to Morales formula, foreign oil corporations were allowed to stay in Bolivia, but were forced to renegociate their contracts, increasing the government take on oil and gas production. Bolivian governments decision has exposed the contradictions of Brazilian foreign policy towards its South American neighbors. Lula, under pressure from conservative opposition, has acted on behalf of Petrobras profits, but at the same time he recognized Bolivian right to set the rules on its own natural resources, and has not taken any reprisal. The thesis explores the ambiguities of Brazilian regional behavior, trying to conciliate a discourse of solidarity to lesser developed neighbors with the international expansion of Brazilian companies and investment protection abroad. The conflict about Bolivian gas has shattered Brazilian plans for regional leadership and turned more difficult energy regional integration, one of the priorities of Lulas foreign policy.
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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. / Flambagem vertical de dutos desencadeada pela pressão interna resultante do transporte de petróleo e gás natural: discussões teóricas e análise geometricamente não linear usando o Método dos Elementos Finitos.Craveiro, Marina Vendl 23 October 2017 (has links)
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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Simulação física e caracterização de zonas afetadas pelo calor de aços API 5L grau X80. / Physical simulation and characterization on heat affected zones of API 5L grade X80 steels.Sanchez Chavez, Giancarlo Franko 07 October 2011 (has links)
Os aços para tubos API 5L X80 são aços de alta resistência e baixa liga (ARBL) usados na fabricação de tubos para o transporte de gás e petróleo conduzidos através de dutos. Os tubos API 5L X80 se caracterizam por terem excelentes propriedades mecânicas como resistência à tração, tenacidade, ductilidade e resistência à corrosão, além de boa soldabilidade. Estes tubos trazem muitos benefícios como, por exemplo, o fator econômico já que ao ter boa resistência mecânica estes tubos podem ser fabricados com espessuras de parede menores. Estas reduções nas espessuras diminuem os custos de transporte, construção, soldagem e instalação. Além disso, estes tubos podem ser fabricados com grandes diâmetros, permitindo o transporte de grandes quantidades de fluidos a elevadas pressões e vazões. A tenacidade confere ao material a propriedade de ser resistente à fratura frágil, uma vez que estes tubos em sua maioria trabalham em condições ambientais severas. O objetivo deste trabalho é simular fisicamente e estudar as propriedades mecânicas de regiões da zona afetada pelo calor (ZAC) produzidas por diferentes ciclos térmicos, que ocorrem quando o tubo é fabricado e o duto montado. A ideia foi estudar a ZAC produzida no tubo fabricado pelo processo UOE (solda longitudinal) e a solda feita no campo quando o tubo é montado (solda circunferencial) além da ZAC na intersecção entre a soldagem longitudinal e circunferencial. Foram usinados corpos-de-prova nas orientações L-T e T-L e com o cordão de solda longitudinal do tubo no centro. Estes corpos-de-prova foram submetidos a quatro ciclos térmicos únicos com temperaturas máximas de 650, 800, 950 e 1300 °C e ciclos térmicos multipasse 950-800 e 950-800- 650 °C. Estes corpos-de-prova foram submetidos a diferentes ensaios e caracterizações. Foram feitos ensaios de impacto a 0 °C, as superfícies fraturadas foram analisadas no MEV e mediu-se a expansão lateral produzida pelo ensaio de impacto. Mediu-se a dureza da microestrutura por meio do ensaio Vickers com 300g de carga. A microestrutura da ZAC foi caracterizada por microscopia óptica, com ataque convencional e ataque colorido Klemm, e microscopia eletrônica de varredura. Metalografia quantitativa foi usada para obter a quantidade de perlita na matriz dos corpos-de-prova. A trajetória da fratura na microestrutura dos corpos-de-prova simulados, provocada pelo ensaio Charpy, foi analisada com microscopia óptica e eletrônica de varredura. Os resultados mostraram que as energias absorvidas no ensaio de impacto pelos corpos-de-prova simulados cumprem com os requisitos exigidos pela norma API 5L para o metal base sem simulação e que as microestruturas observadas variam segundo o tipo de ciclo térmico aplicado a cada posição do tubo. / API 5L Grade X80 steel are high strength low alloy steels (HSLA) used in the manufacture of pipes for transporting oil and gas by pipelines. API 5L X80 pipes are characterized by having excellent mechanical properties such as tensile strength, toughness, ductility, corrosion resistance, and good weldability. These pipes bring many benefits, for example, the economic factor related to the good mechanical strength of these tubes which can be produced with smaller wall thicknesses. This reduction in thickness lowers costs for transportation, construction, welding and installation. In addition, these tubes can be fabricated with large diameters, allowing the transport of large amounts of fluids at high pressures and flow rates. The toughness gives, to this material, the characteristic of being resistant to brittle fracture, since these tubes mostly work in aggressive environmental conditions. The objective of this work is to physically simulate and study the mechanical properties of regions of the heat affected zone (HAZ) produced by different thermal cycles, which occur when the duct pipe is manufactured and assembled. The idea was to study the HAZ produced in the pipe manufactured by the UOE process (longitudinal weld) and the welding done in the field when the tube is mounted (HAZ beyond the intersection between the longitudinal and circumferential welding). Charpy V samples were machined in the L-T and T-L orientations and in the longitudinal weld in the center of the tube. These samples were subjected to single thermal cycles with maximum temperatures of 650, 800, 950 and 1300°C and multipass thermal cycling with maximum temperatures of 950-800 and 950-800-650°C. The samples were subjected to different tests and characterizations. Impact tests were made at 0°C, measured the lateral expansion produced and the surface fracture were examined under SEM. Vickers 300g microhardness was also measured in the simulated HAZ region. The microstructure of the HAZ was characterized by optical microscopy with conventional etching and Klemm colorful etching, and scanning electron microscopy. Quantitative metallography was used to obtain the amount of pearlite in the matrix of samples. The Charpy V fracture propagation path trajectory in the simulated microstructure was analyzed with optical microscopy and scanning electron microscopy. The results showed that the Charpy V absorbed energy by the simulated samples complies with the requirements of the API 5L standard for the base metal without simulation and the HAZ observed microstructures vary according to the thermal cycle type applied to each tube position.
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