998 resultados para Pipe, Steel


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Letter to S.D. Woodruff from A. Jeffrey importer of Hardware, Iron, Steel, and Window Glass of St. Catharines, Ont. A. Jeffrey says that he will be able to supply Mr. Woodruff with glass and iron pipe, June 7, 1875.

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This paper is the first part of an extensive work focusing the technological development of steel fiber reinforced concrete pipes (FRCP). Here is presented and discussed the experimental campaign focusing the test procedure and the mechanical behavior obtained for each of the dosages of fiber used. In the second part ("Steel fiber reinforced concrete pipes. Part 2: Numerical model to simulate the crushing test"), the aspects of FRCP numerical modeling are presented and analyzed using the same experimental results in order to be validated. This study was carried out trying to reduce some uncertainties related to FRCP performance and provide a better condition to the use of these components. In this respect, an experimental study was carried out using sewage concrete pipes in full scale as specimens. The diameter of the specimens was 600 mm, and they had a length of 2500 mm. The pipes were reinforced with traditional bars and different contents of steel fibers in order to compare their performance through the crushing test. Two test procedures were used in that sense. In the 1st Series, the diameter displacement was monitored by the use of two LVDTs positioned at both extremities of the pipes. In the 2nd Series, just one LVDT is positioned at the spigot. The results shown a more rigidity response of the pipe during tests when the displacements were measured at the enlarged section of the socket. The fiber reinforcement was very effective, especially when low level of displacement was imposed to the FRCP. At this condition, the steel fibers showed an equivalent performance to superior class pipes made with traditional reinforced. The fiber content of 40 kg/m3 provided a hardening behavior for the FRCP, and could be considered as equivalent to the critical volume in this condition.

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This paper is part of an extensive work about the technological development, experimental analysis and numerical modeling of steel fibre reinforced concrete pipes. The first part ("Steel fibre reinforced concrete pipes. Part 1: technological analysis of the mechanical behavior") dealt with the technological development of the experimental campaign, the test procedure and the discussion of the structural behavior obtained for each of the dosages of fibre used. This second part deals with the aspects of numerical modeling. In this respect, a numerical model called MAP, which simulates the behavior of fibre reinforced concrete pipes with medium-low range diameters, is introduced. The bases of the numerical model are also mentioned. Subsequently, the experimental results are contrasted with those produced by the numerical model, obtaining excellent correlations. It was possible to conclude that the numerical model is a useful tool for the design of this type of pipes, which represents an important step forward to establish the structural fibres as reinforcement for concrete pipes. Finally, the design for the optimal amount of fibres for a pipe with a diameter of 400 mm is presented as an illustrating example with strategic interest.

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Steel tubular cast-in-place pilings are used throughout the country for many different project types. These piles are a closed-end pipe with varying wall thicknesses and outer diameters, that are driven to depth and then the core is filled with concrete. These piles are typically used for smaller bridges, or secondary structures. Mostly the piling is designed based on a resistance based method which is a function of the soil properties of which the pile is driven through, however there is a structural capacity of these members that is considered to be the upper bound on the loading of the member. This structural capacity is given by the AASHTO LRFD (2010), with two methods. These two methods are based on a composite or non-composite section. Many state agencies and corporations use the non-composite equation because it is requires much less computation and is known to be conservative. However with the trends of the time, more and more structural elements are being investigated to determine ways to better understand the mechanics of the members, which could lead to more efficient and safer designs. In this project, a set of these piling are investigated. The way the cross section reacts to several different loading conditions, along with a more detailed observation of the material properties is considered as part of this research. The evaluation consisted of testing stub sections of pile with varying sizes (10-¾”, 12-¾”), wall thicknesses (0.375”, 0.5”), and testing methods (whole compression, composite compression, push through, core sampling). These stub sections were chosen as they would represent a similar bracing length to many different soils. In addition, a finite element model was developed using ANSYS to predict the strains from the testing of the pile cross sections. This model was able to simulate the strains from most of the loading conditions and sizes that were tested. The bond between the steel shell and the concrete core, along with the concrete strength through the depth of the cross section were some of the material properties of these sections that were investigated.

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This paper presents some experimental data on the size and position of pipes steel ingots as exemp1ified by casting wax under various conditions and noting the size and location of the pipes formed. The results tend to show that the length of the pipe is decreased by: 1. Slow casting 2. By casting large end up instead of down 3. By retarding the cooling of the top

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Un caloducto en bucle cerrado o Loop Heat Pipe (LHP) es un dispositivo de transferencia de calor cuyo principio de operación se basa en la evaporación/condensación de un fluido de trabajo, que es bombeado a través de un circuito cerrado gracias a fuerzas de capilaridad. Gracias a su flexibilidad, su baja masa y su mínimo (incluso nulo) consumo de potencia, su principal aplicación ha sido identificada como parte del subsistema de control térmico de vehículos espaciales. En el presente trabajo se ha desarrollado un LHP capaz de funcionar eficientemente a temperaturas de hasta 125 oC, siguiendo la actual tendencia de los equipos a bordo de satélites de incrementar su temperatura de operación. En la selección del diseño optimo para dicho LHP, la compatibilidad entre materiales y fluido de trabajo se identificó como uno de los puntos clave. Para seleccionar la mejor combinación, se llevó a cabo una exhaustiva revisión del estado del arte, además de un estudio especifico que incluía el desarrollo de un banco de ensayos de compatibilidad. Como conclusión, la combinación seleccionada como la candidata idónea para ser integrada en el LHP capaz de operar hasta 125 oC fue un evaporador de acero inoxidable, líneas de titanio y amoniaco como fluido de trabajo. En esa línea se diseñó y fabricó un prototipo para ensayos y se desarrolló un modelo de simulación con EcosimPro para evaluar sus prestaciones. Se concluyó que el diseño era adecuado para el rango de operación definido. La incompatibilidad entre el fluido de trabajo y los materiales del LHP está ligada a la generación de gases no condensables. Para un estudio más detallado de los efectos de dichos gases en el funcionamiento del LHP se analizó su comportamiento con diferentes cantidades de nitrógeno inyectadas en su cámara de compensación, simulando un gas no condensable formado en el interior del dispositivo. El estudio se basó en el análisis de las temperaturas medidas experimentalmente a distintos niveles de potencia y temperatura de sumidero o fuente fría. Adicionalmente, dichos resultados se compararon con las predicciones obtenidas por medio del modelo en EcosimPro. Las principales conclusiones obtenidas fueron dos. La primera indica que una cantidad de gas no condensable más de dos veces mayor que la cantidad generada al final de la vida de un satélite típico de telecomunicaciones (15 años) tiene efectos casi despreciables en el funcionamiento del LHP. La segunda es que el principal efecto del gas no condensable es una disminución de la conductancia térmica, especialmente a bajas potencias y temperaturas de sumidero. El efecto es más significativo cuanto mayor es la cantidad de gas añadida. Asimismo, durante la campaña de ensayos se observó un fenómeno no esperado para grandes cantidades de gas no condensable. Dicho fenómeno consiste en un comportamiento oscilatorio, detectado tanto en los ensayos como en la simulación. Este efecto es susceptible de una investigación más profunda y los resultados obtenidos pueden constituir la base para dicha tarea. ABSTRACT Loop Heat Pipes (LHPs) are heat transfer devices whose operating principle is based on the evaporation/condensation of a working fluid, and which use capillary pumping forces to ensure the fluid circulation. Thanks to their flexibility, low mass and minimum (even null) power consumption, their main application has been identified as part of the thermal control subsystem in spacecraft. In the present work, an LHP able to operate efficiently up to 125 oC has been developed, which is in line with the current tendency of satellite on-board equipment to increase their operating temperatures. In selecting the optimal LHP design for the elevated temperature application, the compatibility between the materials and working fluid has been identified as one of the main drivers. An extensive literature review and a dedicated trade-off were performed, in order to select the optimal combination of fluids and materials for the LHP. The trade-off included the development of a dedicated compatibility test stand. In conclusion, the combination of stainless steel evaporator, titanium piping and ammonia as working fluid was selected as the best candidate to operate up to 125 oC. An LHP prototype was designed and manufactured and a simulation model in EcosimPro was developed to evaluate its performance. The first conclusion was that the defined LHP was suitable for the defined operational range. Incompatibility between the working fluid and LHP materials is linked to Non Condensable Gas (NCG) generation. Therefore, the behaviour of the LHP developed with different amounts of nitrogen injected in its compensation chamber to simulate NCG generation, was analyzed. The LHP performance was studied by analysis of the test results at different temperatures and power levels. The test results were also compared to simulations in EcosimPro. Two additional conclusions can be drawn: (i) the effects of an amount of more than two times the expected NCG at the end of life of a typical telecommunications satellite (15 years) is almost negligible on the LHP operation, and (ii) the main effect of the NCG is a decrease in the LHP thermal conductance, especially at low temperatures and low power levels. This decrease is more significant with the progressive addition of NCG. An unexpected phenomenon was observed in the LHP operation with large NCG amounts. Namely, an oscillatory behaviour, which was observed both in the tests and the simulation. This effect provides the basis for further studies concerning oscillations in LHPs.

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Copy in Dept. of Rare Books and Special Collections bound in original black leather stamped in gold. P. 9-10 lacking.

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Mode of access: Internet.

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The initiation of stress corrosion cracking (SCC) was studied using scanning electron microscope observations of linearly increasing stress test specimens. SCC initiation from the following surfaces was studied: (i) initiation from the commercial pipe surface covered by the Zn coating, (ii) initiation from a mechanically polished surface with a deformed layer, and (iii) initiation from an electro-polished surface. SCC initiation involved different features for these surfaces as follows. (i) For the Zn coated commercial pipe surface, a crack in the Zn coating led to the dissolution of the deformed layer and when the deformed layer was penetrated, intergranular SCC initiation became possible. (ii) For a mechanically polished surface with a deformed layer, cracks in the surface oxide concentrated the anodic dissolution to such an extent that there was transgranular SCC in the deformed layer. SCC was intergranular when the deformed layer had been penetrated. Transgranular stress corrosion cracks were stopped at ferrite grain boundaries (GBs) oriented perpendicular to the SCC propagation direction. (iii) For an electro-polished surface, the surface oxide film was cracked at many locations, but intergranular SCC only propagated into the steel when the oxide crack corresponded to a GB. An oxide crack away from a GB is expected to be healed. The observed SCC initiation mechanism was not associated with simple preferential chemical attack of the ferrite GBs. (C) 2003 Elsevier Ltd. All rights reserved.