Faculty Publications
Permanent URI for this communityhttps://idr.nitk.ac.in/handle/123456789/18736
Publications by NITK Faculty
Browse
4 results
Search Results
Item Failure analysis of service exposed austenitic stainless steel pipelines(Elsevier Ltd, 2020) Sreevidya, N.; Abhijith, S.; Albert, S.K.; Vinod, V.; Banerjee, I.Several leaks appeared in Austenitic Stainless Steel (ASS) pipelines installed for transporting water in a test loop after a few years of operation at Indira Gandhi Centre for Atomic Research, Kalpakkam. The locations of leaks were mostly on pipe fittings like bends, but a few were noticed on the pipe away from the fittings too. This paper presents the results of failure analysis carried out on leaking of pipes and fittings. Investigation carried out include optical as well as scanning electron microscopy, energy dispersive spectroscopy, electron back scattered diffraction analysis and microhardness measurements. In addition, double loop electrochemical potentio-kinetic reactivation experiments were conducted on specimens extracted from the pipe side and fitting side of a weld that was found leaking. Further ASS pipe welds prepared with different surface finish conditions were exposed to the environment of the installed pipeline and surface degradation in these pipe welds were compared to reveal the effect of surface treatment on degradation of the welds. It is found that the sensitization along with residual stress generated during welding facilitated intergranular stress corrosion cracking in pipe fittings made of AISI 304 stainless steel resulting in the leaks observed in the pipe fittings. Cracks initiated from the corrosion pits present near the weld, which most likely would have formed due to improper cleaning given to the weld zone after completion of the weld. Leak observed in the pipe is attributed to the crevice corrosion that progressed from a defect present in the pipe making it grown across the thickness. The defect itself was result of an improper repair by arc welding, of a discontinuity that was found in the pipe. The pipe is produced from sheets by resistance welding and the origin of the discontinuity is the poor joint formation during resistance welding. The paper also gives recommendation on good fabrication practices to be followed so that similar kind of failures could be avoided in future. © 2019 Elsevier LtdItem Characterization of spatial variability of vertisol micronutrients by geostatistical techniques in Deccan Plateau of India(Springer Science and Business Media Deutschland GmbH, 2020) Vinod, V.; Shetty, A.; Shrihari, S.In vertisols, accounting for the spatial variability of micronutrients is important for sustainable agriculture. In this study, the assessment of spatial variability maps is carried out by the geostatistical technique in SpaceStat 4.0®. A total of 68 random soil samples were collected from small-scale agricultural lands from Kalaburagi, Karnataka, India. The chemical analysis for iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) was carried out in microwave plasma-atomic emission spectroscopy. The coefficient of variation (CV) showed different micronutrients variability (CV > 35%). The significant correlation is among Cu with Fe and Mn (r = 0.753 and 0.258, respectively). The Box–Cox transformation converted the raw data to normal distribution efficiently. Spherical semivariogram model defined the spatial structure for all micronutrients. The nugget/sill ratio specifies that the Zn showed strong spatial dependence and rest micronutrients moderate. Ordinary kriging is applied for generating maps. The spatial variability maps exhibited different distribution pattern; maps generated are utilized as initial guidance for site-specific management practices and the amount of fertilizer application rate planned in the vertisols. The obtained range and spatial distribution maps act as the baseline in this region for administration planners. © 2019, Springer Nature Switzerland AG.Item Geostatistical analysis on spatial variability of soil nutrients in vertisols of Deccan plateau region of North Karnataka, India(International Journal of Mathematical, Engineering and Management Sciences, 2020) Vinod, V.; Shetty, A.; Shrihari, S.Different methods of land use and management have a significant effect on soil properties distribution. Understanding of variations in soil nutrients in agricultural land use is important. An increase in extraction of nutrients, soil degradation, and management of nutrients is leading to a decline in quality of vertisols across the Deccan plateau of India. Though there are studies on spatial variability of vertisols macronutrients, studies on available calcium (Ca) and available magnesium (Mg) are rare. This study is conducted in Gulbarga taluk, north Karnataka, India, to evaluate the variability of soil pH, Ca, Mg, and Zinc (Zn). A total of 78 samples of soils are collected at 0 to 15 cm depth based on the accessibility and distribution of field patterns. Four subsamples represent a single composite sample. Agilent 4200 MP-AES (Microwave Plasma-Atomic. Emission Spectrometer) was used for determining the concentration of soil nutrients. The soil nutrients represent wide variation in coefficient of variation (CV) with a value of 6 % (for pH) to 70.9 % (for Zn). The soil pH showed a significantly positive correlation to Ca and a negative correlation to Mg. Geostatistical investigation indicates spherical model is the best fit for all nutrients. Except for Ca, all nutrients showed moderate spatial dependence. Ordinary kriging is used to generate spatial variability maps. The maps of spatial variability are highly variable in nutrients content and indicate that site-specific management needs to be taken by local authorities and improve the livelihood of marginal farmers and also for sustainable agriculture. © 2020, International Journal of Mathematical, Engineering and Management Sciences.Item Spatial variability of vertisols nutrients in the Deccan plateau region of north Karnataka, India(Springer Science and Business Media B.V., 2021) Vinod, V.; Shetty, A.; Shrihari, S.The status of soil fertility is a concern, especially in the Deccan plateau vertisols of India. Vertisols are productive if they are managed well. Understanding the spatial variability of soil macronutrients is necessary for agriculture to maintain sustainability. The objective of the present study was to explore the spatial variability of macronutrients [available nitrogen (N), available potassium (K), and available phosphorus (P)], soil pH, and electrical conductivity (EC), in scattered small-size fields of northern Karnataka, India. This region is known as the “pigeon pea vessel” of the state. The sixty-eight random topsoil samples were collected from marginal farms, which are less than two acres in size in the study region. The geostatistical analysis is carried out in SpaceStat 4.0® to find the spatial variability of macronutrients, soil pH, and EC. The coefficient of variation monitors the variation in the nutrients of the soil. The variogram analysis has shown K, soil pH, and EC are best fit to spherical model, N and P for an exponential model. According to the ratio of nugget/sill, it indicates they are moderate spatial dependent, excluding N. Using the best fit model, surface maps are generated using ordinary kriging method. The kriged maps exhibited a heterogeneous pattern of macronutrients because of separate farming methods. The spatial variability maps are used as initial regulation by policymakers for site nutrient management, including fertilization in vertisols. This is essential for sustainable and precise management of the fields, which are aimed at increasing the productivity of the crops; low productivity vertisols must be used in cultivation on a global scale due to current shortage of food supplies and agricultural resources land. © 2020, Springer Nature B.V.