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Drumeanu A.C.,Petroleum Gas University of Ploiesti
IOP Conference Series: Materials Science and Engineering | Year: 2017

Frequently the durability of the forging dies is firstly determined by the non-isothermal fatigue wear, which causes the cracks appearance on their internal surfaces, much more before their abrasion wear to reach the limit value. In these conditions it is necessary to design the forging dies firstly by the point of view of the non-isothermal fatigue wear. For a correctly choosing and using of metallic material, it is necessary to determine their intrinsic characteristics regarding its cyclic non-isothermal stresses durability. The experimental determination of these characteristics implies a lot of experiments, which are done in specific conditions, different from those used for isothermal mechanical fatigue durability determination. The paper presents the experimental results concerning intrinsic characteristic determination of the forging dies steel. Based on these results there were determined specific equations which characterize this kind of stresses, and the diagrams that represent their graphic image. These data can be used both in designing and exploitation of the forging dies. © Published under licence by IOP Publishing Ltd.

Dinita A.,Petroleum Gas University of Ploiesti
IOP Conference Series: Materials Science and Engineering | Year: 2017

This article presents a method for assessing the accuracy of the measurements obtained at different tests conducted in laboratories by implementing the interlaboratory comparison method (organization, performance and evaluation of measurements of tests on the same or similar items by two or more laboratories under predetermined conditions). The program (independent software application), realised by the author and described in this paper, analyses the measurement accuracy and performance of testing laboratory by comparing the results obtained from different tests, using the modify Youden diagram, helping identify different types of errors that can occur in measurement, according to ISO 13528:2015, Statistical methods for use in proficiency testing by interlaboratory comparison. A case study is presented in the article by determining the chemical composition of identical samples from five different laboratories. The Youden diagram obtained from this study case was used to identify errors in the laboratory testing equipment. © Published under licence by IOP Publishing Ltd.

Ripeanu R.G.,Petroleum Gas University of Ploiesti
IOP Conference Series: Materials Science and Engineering | Year: 2017

The main failures of heat exchangers are: corrosion of tubes and jacket, tubes blockage and failures of tube to tubesheet joints also by corrosion. The most critical zone is tube to tubesheet joints. Depending on types of tube to tubesheet joints, in order to better respect conditions of tension and compression, this paper analyses the tubesheet holes shapes, smooth and with a grove, on corrosion behavior. In the case of welding tubes with tubesheet, welding parameters modify corrosion behavior. Were realized welded joints by three welding regimes and tested at corrosion in two media, tap water and industrial water. Were tested also samples made of smooth tubes, finned tubes and tubes coated with a passive product as applied by a heat exchanger manufacturer. For all samples, the roughness parameters were measured, before and after the corrosion tests. The obtained corrosion rates show that stress values and their distribution along the joint modify the corrosion behavior. The optimum welding parameters were established in order to increase the joint durability. The paper has shown that passive product used is not proper chosen and the technology of obtaining rolled thread pipes diminishes tubes' durability by increasing the corrosion rate. © Published under licence by IOP Publishing Ltd.

Drumeanu A.C.,Petroleum Gas University of Ploiesti
IOP Conference Series: Materials Science and Engineering | Year: 2017

Polyacrylamide (PAM) is one of the most widely used and technically important water-soluble polymers. Polyacrylamide (PAM) is usually obtained by free radical polymerization of acrylamide (AM) and in its partially hydrolysed form is a synthetic straight-chain polymer of acrylamide monomers, some of which have been hydrolysed. The structure of HPAM molecule is a flexible chain. This kind of structure is known as a random coil in polymer chemistry. Due to the hydrolysed groups contained in its molecule, HPAM has multiple charges distributed along the chain that make it a polyelectrolyte. The paper presents the experimental results concerning the lubricant solutions based on polyacrylamide behaviour when were tested on the four ball machine. It has to be mentioned that this kind of polymer was not used until now in lubrication and the studies concerning its tribological behaviour are at the beginning. © Published under licence by IOP Publishing Ltd.

Agency: European Commission | Branch: FP7 | Program: MC-IRSES | Phase: FP7-PEOPLE-2012-IRSES | Award Amount: 830.30K | Year: 2012

Pipeline systems have supreme significance for an effective functioning of industry providing Eastern and Western European markets with energy resources: crude oil, natural gas and liquid petroleum products. Taking into account long life of pipeline networks and situation, when over 20% of large-diameter pipelines are with an exhausted lifetime, an important task at the present time becomes an ensuring of reliability for these transport systems. An intensive study shows that among the main reasons of pipeline accidents are the volumetric surface defects (VSD) arising as a result of corrosion or erosion-corrosion processes and by this way considerably decreasing the pipeline strength. In order to ensure efficient and safe operation of existing pipelines, operating companies routinely inspect the pipes. The methods that are used for this purpose, like smart pig, are sufficiently expensive, require, in some cases, significant reconstruction and have an insufficient sensitivity. An application of new composite materials for the repair of damaged pipelines considerably improved situation in the last time. However numerous standards associated with this type of repair are based on simplified approaches and do not take into account the stress-strain state in the damaged areas. Strategic objective of the project is addressed to the improvement of infrastructure in EU and Third counties by the rising of reliability of existing pipeline systems. Work over this project will serve IRSES main goal achievement strengthening research partnerships through short period staff exchanges and networking activities between organisations from EU and Third countries. The scientific and technical objectives are improvement of existing and developing of new methods for detection and repair of VSD based on low-frequency ultrasonic testing with directional waves and advanced composite repair systems to bring efficiency of damaged section up to the level of undamaged pipeline.

Cleja-Tigoiu S.,University of Bucharest | Iancu L.,Petroleum Gas University of Ploiesti
International Journal of Plasticity | Year: 2013

This paper is devoted to elasto-plastic orthotropic model within the multiplicative elasto-plasticity, which describes the change of the orthotropic axes, i.e., orientational anisotropy and the strength-differential effect, when the yield condition is pressure insensitive and dependent on the third invariant of the stress. The orthotropy directions are characterized by Euler angles within the constitutive framework with small elastic strains, large elastic rotations and large plastic distortions. The presence of the plastic spin makes possible the description of the orientational anisotropy. We make herein an attempt to develop a hardening model, which includes the kinematic hardening given by Armstrong and Frederick (1966) law adapted to orthotropic material and isotropic hardening, and complies with the experimentally observed plastic yield and flow behaviour reported by Verma et al. (2011) in tension-compression- tension and compression-tension-compression. By pushing away to the actual configuration the material response, the rate form of the model with the objective derivatives expressed via the elastic rotations is characterized by a differential system for the following unknowns: the Cauchy stress, plastic part of deformation, tensorial and scalar hardening variables and Euler angles. We present the rate elasto-plastic model with a plastic spin in the case of an in-plane rotation of the orthotropy direction, and a plane stress, respectively. In the plane stress, the equation for the rate of the strain in the normal direction is first derived and subsequently the modified expression for the plastic multiplier associated with an in-plane rate of the deformation becomes available. Numerical simulations for the homogeneous deformation process on the sheets and comparisons with experimental data make possible a selection among the plastic spins introduced in this paper, aiming at obtaining a good agreement with the experiments performed for an in-plane stress state by Kim and Yin (1997). When the shear deformation of the plate is numerically simulated, the stabilization of the orientational anisotropy occurs in the presence of the plastic spin, in contrast with the unreasonable behaviour produced in the absence of the plastic spin. © 2013 Elsevier Ltd. All rights reserved.

Schwartz W.R.,Yale University | Ciuparu D.,Petroleum Gas University of Ploiesti | Pfefferle L.D.,Yale University
Journal of Physical Chemistry C | Year: 2012

Palladium-based catalysts supported on metal oxides are attractive for methane combustion at low temperature. However, at temperatures below 450 °C, their tendency to deactivate hinders their usefulness. Catalytic deactivation in this temperature regime has been attributed to a water/hydroxyl inhibition effect. We investigated this effect to better understand the mechanism for catalytic deactivation. Comparative in situ FTIR transmission spectroscopy experiments at 325 °C revealed that hydroxyl accumulation occurs on the oxide supports during catalytic methane combustion and deactivation. The water/hydroxyl accumulation on the support is slow to desorb at this temperature. In light of our recent finding that oxygen from the support is utilized in the methane combustion process, we propose that hydroxyl/water accumulation on the support impedes the catalytic combustion reaction by hindering oxygen mobility on the support. We support this hypothesis by demonstrating that the presence of water on the catalyst inhibits oxygen exchange with the oxide support. © 2012 American Chemical Society.

Radulescu G.,Petroleum Gas University of Ploiesti
Revista de Chimie | Year: 2016

A crude oil plant is a classic unit, having one main column, several sidestrippers and pumparounds. Although its steady state modeling and simulation is a well "known-and-solved" problem, only too little is known about the dynamic simulation of such a plant intimacy. The models for that exist, but the open references mention serious difficulties in building-up a dynamic model that could be appropriate for numerical integration. On the other hand, closed commercial tools for crude oil unit study are developed every day, but they limit the user to the models, parameters and state variables that the producing company is willing to provide its clients. Following a series of two other papers [1, 2], which present in detail the problem of a crude oil plant modeling and dynamic simulation, this work makes a step ahead. An open-loop unit detailed response is given and analyzed, and also interesting features (like unit inverse response) are obser ved here, denoting a good agreement with plant experimental data.

Oprea M.,Petroleum Gas University of Ploiesti
International Journal of Artificial Intelligence | Year: 2012

Artificial intelligence provides a variety of techniques and methods that can be implemented in the environmental decision support systems, for solving different problems such as forecasting, analysis, diagnosis, control and planning, for a better quality of the environment and, thus, of the life. The paper presents an intelligent system, INTELLEnvQ-Air that was developed for air quality analysis in urban regions and for informing the population about the impact of air pollution on human health and possible measures of protection for vulnerable persons. The system integrates two artificial intelligence approaches: feed forward artificial neural networks, for air pollutants concentrations forecasting, and rule-based expert systems for the analysis of air quality and human health impact. © 2012 by IJAI (CESER Publications).

Popa C.,Petroleum Gas University of Ploiesti
Procedia Engineering | Year: 2014

This paper presents an application of plantwide control strategy for a complex process, like catalytic cracking process. The plantwide control strategy assists the engineer in determining how to choose the best manipulated, controlled and measured variables in the plant, when is using advanced control techniques such MPC. The result of applying plantwide control to catalytic cracking process is a hierarchical control structure, which is organized on three levels, with two advanced control techniques for the second level. From economic point of view, the development and the implementation a hierarchical control structure for the catalytic cracking process is leading to increase plant efficiency. © 2014 The Authors. Published by Elsevier Ltd.

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