Behaviour of laterised normal and self compacting concrete subjected to elevated temperatures

Concrete is a universal material in the construction industry. With natural resources like sand and aggregate, fast depleting, it is time to look for alternate materials to substitute these in the process of making concrete. There are instances like exposure to solar radiation, fire, furnaces, and nuclear reactor vessels, special applications like missile launching pads etc., where concrete is exposed to temperature variations In this research work, an attempt has been made to understand the behaviour of concrete when weathered laterite aggregate is used in both conventional and self compacting normal strength concrete. The study has been extended to understand the thermal behaviour of both types of laterised concretes and to check suitability as a fire protection material. A systematic study of laterised concrete considering parameters like source of laterite aggregate, grades of Ordinary Portland Cement (OPC) and types of supplementary cementitious materials (fly ash and GGBFS) has been carried out to arrive at a feasible combination of various ingredients in laterised concrete. A mix design methodology has been proposed for making normal strength laterised self compacting concrete based on trial mixes and the same has also been validated. The physical and mechanical properties of laterised concretes have been studied with respect to different variables like exposure temperature (200°C, 400°C and 600°C) and cooling environment (air cooled and water cooled). The behaviour of ferrocement elements with laterised self compacting concrete has also been studied by varying the cover to mesh reinforcement (10mm to 50mm at an interval of 10mm), exposure temperature and cooling environment.

Análise de estruturas de superfície delgadas axissimétricas via método dos elementos finitos com utilização de elemento retilíneo

The present work deals with the linear analysis of bi-dimensional axisymmetric structures, through development and implementation of a Finite Element Method code. The structures are initially studied alone and afterwards compatibilized into coupled structures, that is, assemblages, including tanks and pressure vessels. Examples are analysed and, in order to prove accuracy, the results were compared with those furnished by the analytical solutions

Simulação de reservatórios não convencionais para armazenamento de gás natural veicular

The investigation of viability to use containers for Natural Gas Vehicle (NGV) storage, with different geometries of commercial standards, come from necessity to join the ambient, financial and technological benefits offered by the gas combustion, to the convenience of not modify the original proposal of the automobile. The use of these current cylindrical models for storage in the converted vehicles is justified by the excellent behavior that this geometry presents about the imposed tensions for the high pressure that the related reservoirs are submitted. However, recent research directed toward application of adsorbent materials in the natural gas reservoirs had proven a substantial redusction of pressure and, consequently, a relief of the tensions in the reservoirs. However, this study considers alternative geometries for NGV reservoirs, searching the minimization of dimensions and weight, remaining capacity to resist the tensions imposed by the new pressure situation. The proposed reservoirs parameters are calculated through a mathematical study of the internal pressure according to Brazilian standards (NBR) for pressure vessels. Finally simulations of the new geometries behavior are carried through using a commercially avaible Finite Element Method (FEM) software package ALGOR® to verify of the reservoirs efficincy under the gas pressure load

Efeitos dos tratamentos térmicos de normalização, resfriamento rápido e alívio de tensões no aço ASTM A-516 grau 70, utilizado na fabricação de vasos de pressão

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Análise crítica de um vaso de pressão do setor sucroalcooleiro

This study aims to evaluate structurally a heat exchanger that has been in operation since the mid-60's and was built COSAN for operation in one of its sugar production plants in São Paulo, this equipment as well as many similar devices are operation in plants throughout Brazil, and thus to be acquired by large corporations as in the case of COSAN, pass the scrutiny of inspection work, and work such as recalculations in the latter case in structural evaluations to verify the possible need for adjustments to project or operation and thus ensure the structural integrity of the equipment. To this were first done field survey using techniques of NDT and NDT's for determining the thickness of the main parts of the equipment, made the revaluation dimensional and existing project and considering the loads operating performing the characterization of the equipment as specified in the standard regulatory number 13 - NR13 and the other for this type of equipment and finally an analysis using a static approach, as an analysis tool using the finite element method

Desenvolvimento de vasos digestores de amostra para microondas doméstico

The application of microwave radiation on the sample preparation has been expanding increasingly in areas involving decomposition by wet and dry roads, fusion, extraction, acceleration of chemical reactions, for example. Currently, the use of microwave ovens for analytical purposes are recognized for having excellent performance for organic and inorganic samples. In the international market there are several kinds of microwaves oven which adapt the varied purposes, however yet with elevated prices which incapacitate your use as routine equipment in laboratory. Thus, many researchers have been choosing for developing own projects of microwaves oven production or to use domestic oven for the laboratory, with or without adaptations. For the evaluation of the proposed method was used in the Kjeldahl methodology for determining total nitrogen in samples of crude protein, using a domestic microwave oven and a digester pot made up in TeflonTM and distillation by steam. Were made to adapt and characterization of a domestic microwave oven, the confeccion vessel digester and the metal support for the vessel. The accuracy of the proposed method was confirmed by comparison of two methods, the standard method for conventional heating and by the proposed method, with heating by microwave radiation through the calculated values of relative standard deviation analysis

Determinação por meio de planejamento de experimentos da influência do lixamento nas medidas de dureza com durômetro portátil de método UCI

The hardness has an important role in quality control, in research studies and metallurgical and mechanical specification, selection and comparison of various materials. This property is of extreme importance in the oil industry because it is a determining factor to ascertain the safety of the material used in pressure vessels and pipelines. Due to the inability to stop the equipment while checking the hardness, the hardness testers are widely used portable method UCI, its great advantage is the fact that an essay fast, simple realization and not be considered a non-destructive testing with a good relationship money. The objective is to determine if there is significant difference in hardness measurements between 80 and 1200 sandpaper using a portable hardness tester UCI method, the material applied in gas storage spheres composition ASTM 516 Gr 70. After determining the number of homogeneity, we performed the hardness profile to isolate the major factors influencing the hardness part: cold rolling and segregation of impurities. Factors Cooling and sanding were analyzed using the method of design of experiments (DOE), in which it was demonstrated that neither variables nor their interactions, has significant influence on the hardness measurements by portable MIC 10. This fact will lead to reduction in time and cost for surface preparation

Distribuição de tensões em bocais de vasos de pressão

This work is to analyze the behavior of context concentrated stresses generated around a nozzle connected to a pressure vessel. For this analysis we used the finite element method via a computer interface, the software ANSYS WORKBENCH. It was first necessary to study and intensive training of the software used, and also a study of the ASME Code, Section VIII, which is responsible for the standards used in pressure vessels. We analyzed three cases, which differ primarily in the variation of the diameter of the nozzle in order to analyze the variation of the stresses according to the variation of the diameters. The nozzle diameters were 35, 75 and 105 mm. After the model designed vessel, a pressure was applied on the innervessel of 0.5 MPa. For the smallest diameter, was found the lowest tensions concentrated. Varying between 1 and 223 MPa. Increasing the diameter of the nozzle resulted in increased tensions concentrated around the junction nozzle /vessel. The maximum stresses increased by 78% when the value was increased in diameter from 35 to 75 mm. Since the increase in diameter from 75 to 105 mm, the values of the tensions increased around 43%. These figures emphasize that stress concentrations increased with increasing the diameter of the nozzles, but not linearly

Diretrizes básicas para projetos de vasos de pressão segundo a ASME Trabalho

In this work it was made analysis of a simple pressure vessel, using the analytical development studied in Mechanics of Materials disciplines, and then using the standard required by ASME. Following the simulation was realized using Autodesk Mechanical Simulation software to calculate the principal stresses in a pressure vessel. The simulation was done in a single vessel without nozzles, compared with the analytic calculation. After that, the simulation of another fictitious pressure vessel was done by adding three nozzles to verify the influence of the nozzles in the principal stresses and compared with the analytical results. After the simulation, it was found that the principal are bigger in the pressure vessel with nozzles, but they decrease at a small distance from the nozzle becoming equal to the stresses in the vessel without nozzles. The analytical results calculated according to the ASME agree with simulated results

Estudo das alterações das propriedades mecânicas em aço A-516 grau 70 soldado e submetido a tratamento térmico de alívio de tensões

Pressure vessels are equipments that require a great care because of their high cost and human life risk in case of fail, and its fabrication methods are different for each manufacturer. Normally, pressure vessels and its parts are fabricated by welding, which may change local properties of metals. The head of a pressure vessel is a very important structural component and it is fabricated by welding and mechanical conformation. Because its excellent mechanical properties, de steel A-516 Grade 70 is often used in manufacturing of large pressure vessels that are subjected to high pressure and temperature, but was verified that its mechanical resistance is decreased when submitted to a tension relief heat treatment. By experience it was defined that before mechanical conformation of the head of a large pressure vessel, the steel should be submitted to a stress relief heat treatment in order to facilitate the mechanical conformation, but there is no quantitative analysis to prove this method and study its possible risks. In the present work the steel A-516 Grade 70 demonstrated a decrease of its mechanical resistance when submitted to a stress relief heat treatment, but keeping above the minimum limit defined in the literature. By other side its ductility was substantially increased, being possible to deduce that the stress relief heat treatment before mechanical conformation is a viable e recommended technique, but with reservations. With the data acquired during the fabrication e preparation of the specimen and the result of the tests, it was possible to elaborate a welding procedure that provides the same results obtained in this present work

Tratamento térmico de normalização em tampos de vasos de pressão fabricados de material P275NH

In a market environment increasingly competitive, the companies need to control of this process accurately, avoiding rework or rejection of materials during industrialization. This can be achieved by defining procedure that assure the maintenance of the materials characteristics, as specified initially in the projects. This graduation work has the objective of defining the best heat treatment parameter of normalizing for Heads, part of a pressure vessel, formed in P275NH material. The methodology applied is based on the execution of a sequence of Heat Treatments, using different parameters. The process variables were the cooling velocity, the hold time and the hold temperature variation. As a result of this study, it is noticed that the mechanical properties of the materials are strongly influenced by the hold temperature variation and by the cooling velocity, both determined for the heat treatment cycle

Determinação comparativa do grau de deformação plástica aplicado a componentes obtidos por conformação

The manufacturing process of components of Pressure Vessels has a great importance in the efficiency during the operation and life cycle of the equipment. Taking this into account, the objective of this dissertation was to analyze the methods to determine the strain rate in formed components by measuring the components themselves, and posterior results comparison with the values found in manufacturing standards of Pressure vessels. In this study the whole manufacturing process of a component from a pressure vessel, known as Head or End, was accompanied. Using the methodology obtained from literatures it was possible to execute the relative and logarithmic deformation measurements of these components and compare with the obtained results by means of equations presented in the Standards as AD-Merkblatt and ASME (for pressure vessels). The found results were also compared with the logarithmic methodology, taking into account the deformation of the empirical mesh and the thickness of the components studied. It is possible to conclude from this study that despite the existence of empirical methods of measurement of strain rate in components plastically formed, it is recommended the adoption in all situation of the component manufacturing standard. It can be noticed and explained during the development of this study and through the results found

Tratamento térmico de normalização em tampos de vasos de pressão fabricados de material P275NH

In a market environment increasingly competitive, the companies need to control of this process accurately, avoiding rework or rejection of materials during industrialization. This can be achieved by defining procedure that assure the maintenance of the materials characteristics, as specified initially in the projects. This graduation work has the objective of defining the best heat treatment parameter of normalizing for Heads, part of a pressure vessel, formed in P275NH material. The methodology applied is based on the execution of a sequence of Heat Treatments, using different parameters. The process variables were the cooling velocity, the hold time and the hold temperature variation. As a result of this study, it is noticed that the mechanical properties of the materials are strongly influenced by the hold temperature variation and by the cooling velocity, both determined for the heat treatment cycle

Determinação comparativa do grau de deformação plástica aplicado a componentes obtidos por conformação

The manufacturing process of components of Pressure Vessels has a great importance in the efficiency during the operation and life cycle of the equipment. Taking this into account, the objective of this dissertation was to analyze the methods to determine the strain rate in formed components by measuring the components themselves, and posterior results comparison with the values found in manufacturing standards of Pressure vessels. In this study the whole manufacturing process of a component from a pressure vessel, known as Head or End, was accompanied. Using the methodology obtained from literatures it was possible to execute the relative and logarithmic deformation measurements of these components and compare with the obtained results by means of equations presented in the Standards as AD-Merkblatt and ASME (for pressure vessels). The found results were also compared with the logarithmic methodology, taking into account the deformation of the empirical mesh and the thickness of the components studied. It is possible to conclude from this study that despite the existence of empirical methods of measurement of strain rate in components plastically formed, it is recommended the adoption in all situation of the component manufacturing standard. It can be noticed and explained during the development of this study and through the results found

Effects of specimen geometry and loading mode on crack growth resistance curves of a high-strength pipeline girth weld

This work presents an investigation of the ductile tearing properties for a girth weld made of an API 5L X80 pipeline steel using experimentally measured crack growth resistance curves. Use of these materials is motivated by the increasing demand in the number of applications for manufacturing high strength pipes for the oil and gas industry including marine applications and steel catenary risers. Testing of the pipeline girth welds employed side-grooved, clamped SE(T) specimens and shallow crack bend SE(B) specimens with a weld centerline notch to determine the crack growth resistance curves based upon the unloading compliance (UC) method using the single specimen technique. Recently developed compliance functions and η-factors applicable for SE(T) and SE(B) fracture specimens with homogeneous material and overmatched welds are introduced to determine crack growth resistance data from laboratory measurements of load-displacement records.