The financial cost of downtime can be very significant, especially in manufacturing industries. As a result, no business wants to experience downtime. In this study, the reliability of two identical machines code named GDA and GDB used in a cement manufacturing industry was assessed by analysis of failure times data of components in the machines by applying Weibull distribution method. The estimates of the Weibull parameters, θ and β were obtained using a reliability software tool ‘Windchill Quality Solutions 11.0 Tryout’ and the mean time to failure, failure rate and reliability of the machines was successfully determined. The result obtained showed that, the machines are undergoing rapid wear out as the values of the shape parameter obtained were greater than four. The plots of the failure rate also showed that the machines are in their wear out periods as the failure rate curves were observed to be increasing. The values of the mean time to failure of the two machines were found to be very close. The reliability of the machines was found to be increasing as their values of scale parameter, θ increases with machine GDA having the highest reliability.
The microstructure of a weldment can be maintained by ensuring a steady state homogenous melting profile of the welding operation, which includes the deposition of optimum volumes of melted filler wire and substantial part of the heat affected zones of the parent metal to form the weld pool. The melting pattern of the entire welding process should be protected from atmospheric air, so as to enhance weldment quality. In this study, the melting profile of mild steel is investigated by looking at the parent metal angular distortion bead width and penetration volumes of deposited filler and the melting efficiency was determined. Predictive models were also developed to determine the above listed melting properties by applying the regression analysis. The result obtained showed that, there is almost a perfect fit between the calculated and predicted angular distortion, as well as between the calculated and predicted volume of filler wire melted. There is also a close correlation between the calculated and predicted melting efficiency. However, for the bead width, bead penetration and volume of weld metal deposited, there were variations of values and a heterogeneous correlation between the calculated, measured and predicted values. The effects of the process parameters on the obtained properties of the melting profile were investigated and optimum process parameters were determined.
The focus of this study was to investigate the impact of corrosion attack in carbon steel C-1040 marine piping system using weight loss method. Two carbon steel specimens (coupons) of cylindrical shape were selected and weighed before they were exposed to two different test solutions (corrosion media) at a concentration of 0.2M and 0.04M in seawater and freshwater respectively at room temperature for eight weeks. The weight loss was taken as the difference in the weight of the coupons before and after immersion in the two different test solutions. The corrosion rates of the coupons were calculated from the weight loss obtained. The experimental result from weight loss method was calculated using engineering equation solver (EES). The weight loss and rate of corrosion of the two coupons varied as higher corrosion rate and weight losses were observed in coupon 2. The weight loss and corrosion rate in 0.2M concentration of coupon 2 in seawater environment increased from 0.04 g to 0.53 g, 0.007133 mmpy to 0.0181 mmpy while coupon 1 showed an increase from 0.01 g to 0.25 g, 0.0035 mmpy to 0.005573 mmpy was observed in 0.04M concentration in freshwater environment. This shows that carbon steel metal was more susceptible to corrosion attack in seawater environment than in the freshwater environment. The micrograph results of coupon 2 before and after immersion in 0.2M of seawater for about 1344 hrs showed evidence of uniform (general) corrosion as the coupon surface was rough and jarring. The grain boundaries of the surface morphology also revealed general corrosion effects on the coupon after immersion as the film present on the surface was cracked as a result of corrosion impact.
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