Technical Inspection Engineering
Gholamreza Rashed; maryam salehi; Mohammadreza Shishesaz; Iman Danaee
Abstract
The effect of using Conocarpus extract as a green inhibitor on the corrosion behavior of mild steel in a 1M HCL environment was investigated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy ...
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The effect of using Conocarpus extract as a green inhibitor on the corrosion behavior of mild steel in a 1M HCL environment was investigated by electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), scanning electron microscopy (SEM), and Fourier-transform infrared spectroscopy (FTIR). The impedance test showed that the polarization resistance increased from 29 for the blank solution to 299 for the solution containing 2500 ppm of Conocarpus extract. The results of the polarization test showed that at room temperature, the corrosion current density for the blank solution decreased from 3.5E-4 to 2.6E-5for the solution containing 2500 ppm of Conocarpus extract, and the potential was shifted to negative values. The polarization test was performed at three temperatures of 25, 55, and 85. The results showed that the efficiency of 1925 ppm has decreased from 93% at room temperature to 86% at 85 ° C. Obviously, the high-temperature efficiency has not reduced significantly, which means the effectiveness of Conocarpus extract at high temperatures. FTIR test also proved that the corrosion inhibitory effect of Conocarpus extract is due to the presence of heteroatoms such as N, S, and O. The adsorption isotherm results showed that the adsorption of the extract as a single layer on the surface is consistent with the Langmuir isotherm.
Mechanical Engineering – Applied Design
Gholamreza Rashed; Hadi Eskandari; Ardeshir Savari
Abstract
The purpose of this study is to investigate bending moment and the axial load capacity of a pressurized pipe suffering from a through-wall circumferential crack repaired by a composite sleeve. The three-dimensional finite element method (FEM) was adopted to compute the results, and the failure assessment ...
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The purpose of this study is to investigate bending moment and the axial load capacity of a pressurized pipe suffering from a through-wall circumferential crack repaired by a composite sleeve. The three-dimensional finite element method (FEM) was adopted to compute the results, and the failure assessment diagram (FAD) was employed to investigate the failure behavior of the repaired pipe. The findings revealed that, for the investigated range of applied loads and angles of the crack, the interaction of brittle and ductile failure modes is negligible. Additionally, the yield strength of the cracked pipe was considered as reference stress to achieve a conservative design. Two cases of the combined loading state consisting of internal pressure/bending moment and internal pressure/axial tensile force were investigated. Repairing the crack under combined loadings using carbon-epoxy composites was studied where the influences of various parameters, including internal pressure, crack angle, and the composite patch thickness on the capacity of the cracked pipe to withstand bending moment and axial load were included. The results indicated that the bending moment and axial load capacities of the cracked pipe depend on internal pressure, crack angle, and the composite patch thickness; nevertheless, the crack angle is the main parameter. A composite sleeve can increase both bending moment and axial load capacity of the cracked pipe, but bending moment can be increased further than axial load. Using the composite patch to repair the cracked pipe caused the bending moment capacity to improve from 14.28% to 120%. On the other hand, the composite patch raised the axial load capacity from 5.1% to 93.5%. Additionally, an increase in the composite patch thickness caused the axial load capacity to extend more than bending load capacity.
Elahe Shekari; Mohammad Reza Shishesaz; Gholamreza Rashed; Mansoor Farzam; E Khayer
Abstract
The current study assesses the root causes of hydrogen blisters on low strength carbon steel equipment. For this purpose, some experiments including hardness test, non-destructive test (NDT), metallography, and fractograpghy are conducted. The microstructure of two blisters is assessed by means of optical ...
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The current study assesses the root causes of hydrogen blisters on low strength carbon steel equipment. For this purpose, some experiments including hardness test, non-destructive test (NDT), metallography, and fractograpghy are conducted. The microstructure of two blisters is assessed by means of optical microscopy and scanning electron microscopy (SEM). The microstructural studies show that the steel plate has some inclusions and banded ferrite/pearlite structure. The energy dispersive x-ray spectroscopy (EDS) results indicate that these inclusions mainly contain Mn, S, Al, Ca, and Si. The results show that the inclusions and planar imperfections found in the NDT have been the nucleation locations for blisters in the plate. Remediation action plans are recommended to prevent further occurrence and growth of hydrogen blisters.
