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The Finite Element Method in the function of corrosion damage assessment of pipelines
Get PDFPipelines, with specifics in design, construction, testing and safety requirements must be designed
based on all relevant influences to ensure that they are safe during their working life. Allowable
stresses must be limited by possible errors in working conditions, in order to completely eliminate
the uncertainty arising from the production, the calculation model, the actual working conditions and
the characteristics and behavior of the material. In the paper, on the example of modeling and
calculation of the corrosion-damaged structure of the ammonia (NH3) transfer pipeline, a
methodological approach to the calculation using the Finite Element Method (FEM), is shown, in
accordance with the methods defined by the new and general approach to standardization and
technical harmonization for pressure equipment (Pressure Equipment Directive - PED 97/23 EC).
The paper uses advanced modeling techniques of corroded surfaces, based on FEM, with the aim of
developing a procedure for assessing the residual strength of steel pipelines operating in the
environmental conditions of the chemical products industry. The presentation of possible damages
and consequences caused by the corrosion of steel pipelines in the chemical products industry is also
given, and the possibility of taking measures to prevent such occurrences is discussed
Negative impacts of petroleum coke as an energy source in the brick-making industry
Get PDFThe technical features of the issues caused by the brick industry's usage of petroleum coke as a fuel were identified in this study. The effects were evaluated in terms of the concentration of hazardous materials in petroleum coke, the CO2, SO2 and NOx emissions in the flue gases, the corrosion of refractory materials in the furnace, the corrosion of pipelines and metal structures in the dryer and furnace, the deposition of sulfate scum on dry products, and the fixation of white scum on finished products. To assess the microstructure and composition of the regions of the samples exposed to flue gases and that inside the material, refractory brick samples from the furnace walls were examined under a microscope. The compressive stress of the part of the sample affected by the flue gas from the kiln is lowered by 37.3 %, which is caused by the agglomeration of sulfate salts and the presence of a high quantity of vanadium. It was determined that, regardless of potential energy savings, the sulfur concentration in petroleum coke must be below 5% if utilized as an energy source in the brick sector since there are suitable conditions for accelerated corrosion processes
Naučnoistraživački projekat MoDeCo2000. Realizacija projekta u 2020. godini
Get PDFProjekat MoDeCo2000 (Dizajn maltera za konzervaciju – Rimska granica na Dunavu 2000 godina kasnije/Mortar Design for Conservation – Danube Roman Frontier 2000 Years After: MoDeCo2000) jeste naučnoistraživački projekat finansiran iz programa PROMIS, Fonda za nauku Republike Srbije. Trajanje projekta iznosi dve godine, od sredine 2020. do sredine 2022. godine. Nosilac projekta je Arheološki institut, koga zastupaju dr Emilija Nikolić (rukovodilac) i dr Mladen Jovičić. Arheološki institut projekat sprovodi zajedno sa Institutom za ispitivanje materijala u Beogradu (Ljiljana Miličić, Ivana Delić Nikolić) i Tehnološkim fakultetom Univerziteta u Novom Sadu (dr Snežana Vučetić, dr Jonjaua Ranogajec). Članovi istraživačkog tima su stručnjaci različitih naučnih oblasti, kako humanističkih tako i tehničko-tehnoloških i prirodnih, te je multidisciplinarni pristup svakako jedna od najvećih vrednosti projekta
Construction and demolition mix waste in traditional ceramics
No full textIn this paper, the drying modeling of roofing tiles was done using a "lumped" approach. In other words, several forces that are influencing internal moisture transport are combined to create effective moisture diffusivity. For this reason, the effective diffusivity coefficient was added to Cranck's diffusion equation. In their earlier works, the authors published the solution to the diffusion equation, which assumes that effective diffusivity is constant. It was demonstrated that, particularly if shrinkage is not taken into account during the computation stage, the simulated drying curves differ from the experimental results. The next step was to ascertain the time-dependent effective diffusivity and to more precisely anticipate the drying kinetic. The general functional relationship between effective moisture diffusivity and Fourier number was first determined to fulfill this assignment. Experimental proof of the proposed model was provided. Less than 3% of the outcomes from the simulation and the experiment deviated from each other. This was a resounding affirmation that effective diffusivity is not constant during drying and that all internal transport mechanisms are observable in their time-dependent relation
Application of pyrophyllite in high-temperature treated building materials
Get PDFPhyllosilicate mineral pyrophyllite is predominantly used in the ceramic industry because it exhibits high refractoriness. Due to its thermal transformation into mullite, pyrophyllite is stable at elevated temperatures, making it a suitable mineral additive for refractory non-shaped materials and various ceramic shaped products. In this study, pyrophyllite is employed as 50 % clay replacement in the ceramics and up to 30 % cement replacement in mortars. Physico-mechanical properties were investigated. The firing shrinkage in the ceramics treated at 1200°C was reduced by pyrophyllite addition. Pyrophyllite acted as additional pozzolana during cement hydration. Within the microstructure, it formed micro-reinforcement in the shape of crystalline folia, which improves the mechanical properties of ordinary Portland cement, high aluminate cement, and blended cement mortars. The investigation proved the efficiency and suitability of pyrophyllite employed as a substitution for clay in ceramics and a cement replacement in mortars
Connectivity approach in urban protected area management based on soil and vegetation chemical status
No full textThe quality and vitality of cities largely depend on the design, management, and maintenance of green areas, including urban protected areas (UPAs), since they provide multiple benefits for the city. Due to urbanization and higher anthropogenic pressure, green areas are decreasing which directly affects natural habitats and biodiversity. This study aims to assess soil and vegetation chemical status in UPAs in the city of Belgrade, Serbia, and to understand how their distance from pollution hotspots affects soil and vegetation quality. Additionally, this paper considers the inclusion of soil and vegetation conditions in the urban protected areas management as a basis for introducing a connectivity approach to expand green infrastructure throughout the city. Chemical properties, the content of nutrients (C, N, P, and K), and microelements (Cr, Co, Ni, Cu, Zn, As, Cd, Sn, Pb, Zr, U, and Th) in soil and conifer needles were analyzed. Results showed that the distance of pollution hotspots does not affect nutrient and microelements concentrations in soil, i.e., they do not vary significantly between sites and do not exceed remediation intervention values. However, the microelements status of vegetation is affected since Cr, Cu, Zn, Sn, and Pb are higher in needles from trees from the city center. The state of soil and plant composition supports the establishment of a network of green corridors and should become a part of management strategies, thus helping biodiversity protection, climate change mitigation, and human well-being in the cities
The macro- and microelements content in Cedrus atlantica (Endl.) Manetti ex Carrière (Pinaceae) needles as an indicator for assessing the environmental status
No full textThe main objective of this study was to analyze the capacity of Cedrus atlantica (Endl.) Manetti ex Carrière 1855 to accumulate macro- and microelements in order to assess the environmental status. The element concentrations were measured using X-ray Fluorescence (XRF) analysis. The obtained pH values in this study show that the urban soils are neutral to slightly alkaline with low OM content. Macroelements with the highest mean concentrations in soil are Si, Al, Fe, K, Mg, and Ca. The ratio > 2 was determined for mean concentrations of Ca in the soil and Mg in needles from the Zvezdara forest, and for mean concentrations of Cl, Ti, and Fe in needles from the Byford’s forest in relation to the reference site. The accumulation pattern of the macroelements based on the Biological Concentration Factor (BCF) values > 1 for needles is for P, S, Cl, and Ca. Microelements with the highest mean values in soil are Ba, Zr, Ce, Cr, Zn, Rb, Sr, V, and La. Microelements with the highest mean values in Atlas cedar needles are Ce, La, Ba, and Cs. The ratio > 2 was determined for Cr and V concentrations in the needles from the Byford’s and Zvezdara forests and for Cu concentrations in needles from the Byford’s forest in relation to the reference site. The accumulation pattern of the microelements based on the BCF for needles is higher for I, Cs, Mo, Ag, Cd, In, Sn, Sb, and Tl. Since differences in the concentrations of macro- and microelements in the urban areas and the reference site can be identified C. atlantica can be recommended for assessing the environmental status
Influence of Aggregate Type on the Properties on SCC with Fly Ash
No full textThis study compared the performance of self-compacting concrete (SCC) based on fly ash addition and limestone filler. A SCC prepared with Portland cement, river sand, and limestone filler was used as a reference sample. Additional experimental self-compacting concretes with different types of fine aggregates, fillers, and special additives for increasing freeze-thaw resistance were prepared and optimized. The correlation between mix design, i.e., percentage of barite sand and additives, and properties of fresh SCC (slump-flow test, V-funnel test, and L-box test), as well as properties of hardened SCC (compressive strengths), were investigated and discussed
Socio-Economic Analysis of the Construction and Building Materials’ Usage—Ecological Awareness in the Case of Serbia
Get PDFThe main idea of the present study was to investigate the impact of the ongoing world
crisis on the socio-economic issues in Serbia concerning building materials usage and purchase. This research fills in the gaps in the literature and contributes to the comprehension of how the crisis has affected salaries, market pricing, and materials consumption in the building sector. The data are gathered through a questionnaire and analyzed using a statistical methodology (frequencies, descriptive statistics, and Spearman’s correlations). Most of the former studies investigated the surveys conducted on specialists in the field, while this study analyzed the perspectives of random people. Socio-demographic issues are analyzed along with materials consumption before and after the crisis. A special emphasis is given to ecological awareness and novel materials usage. Additionally, it captures a broad shift in the economy and ecological consciousness in a developing country. The majority of respondents are open to using novel building materials and products, but their choice would largely be influenced by cost, the amount of effort involved, and their understanding of the advantages. Statistical approaches revealed that the crisis has a considerable impact on the markets for construction and building supplies, altering consumers’ decisions when purchasing.
This contribution lays the groundwork for developing countries in the modern world to improve
sustainability and adopt circular thinking. Professionals in Serbia need to have a more eco-aware
mindset and enhance how they provide pertinent information to potential clients. This study is
limited by the number of respondents. For future mathematical modeling and forecasting, more
answerers are needed
Uporedna statistička analiza zagađenja površinskog sedimenta iz priobalnih i centralnih delova Bokokotorskog zaliva za period od 2005. do 2019. godine
No full textPet kompleksnih indeksa (PLI, RI, mERMq, TRI, CSI) određeno je za svaku od 40 lokacija tokom perioda istraživanja (2005, 2007, 2013, 2019) uzimajući u obzir osam teških metala. Primenom klasterske analize (CA) i analize glavnih komponenti (PCA) na vrednosti indeksa zagađenja, izvršeno je prostorno i vremensko poređenje kvaliteta sedimenta. Rezultati statističke analize pokazali su povišen stepen kontaminacije sedimenta u 2005. godini u Kotorskom i Tivatskom zalivu, dok je u 2007., 2013., i 2019. godini bio u Tivatskom zalivu. PCA, CA i indeksi zagađenja ukazali su na povećanje nivoa zagađenja sedimenta u Tivatskom zalivu u periodu od 2005. do 2019