Associated gas is a viable source of fuel for industrial gas turbines. Flaring of this fuel resource has not only resulted in environmental pollution and deterioration but also huge energy and economic loss. TURBOMATCH, a Cranfield University performance simulation software was used in modeling a hypothetical but realistic 296MW reheat gas turbine engine.The study was carried out using one clean fleet and three degraded fleets – the optimistic, medium, and pessimistic. Optimization of the fleet compositions and thermal efficiencies were achieved using Genetic algorithm. Detailed operations and maintenance costs analysis for the various fleets were carried out. .Results from the optimization show the optimized fleet compositions, from the various fleets and their turbine entry temperatures for 20 years life span of the project. the result from the 11th to the 20th year of the project, only one unit of engine was left due to engine divestment.  Results of the optimized efficiencies for all the fleets show a gradual reduction in optimized efficiencies over the years of the project. Similarly, for all the scenarios considered, from the 11th to the 20th year of the project, with only one unit of engine left, the optimized efficiency trend is observed to be Clean > Optimistic > Medium > Pessimistic.Results from the fleets operations and maintenance costs show that the clean, optimistic, medium, and pessimistic degraded fleets have total operations and maintenance costs to be 1.224, 1.242, 1.265, and 1.297 billion US dollars respectively. Engine degradation resulted to 1.4%, 3.3%, and 5.9% increase in the operations and maintenance costs of the optimistic, medium, and pessimistic degraded fleets respectively.The results, approach and methodology presented in this paper would be a very useful decision-making tool for investors and governments who would want to invest in the economic utilization of associated gas using gas turbines.

Welded joints sometimes exhibit poor corrosion resistance, due to variation in chemical composition at the weld surface or Heat Affected Zone (HAZ), induced stress and the microstructure formation. There is a need to enhance welds corrosion resistance and microstructural properties of such joints through post weld tempering (PWT). In this study, PWT effect on the corrosion resistance and microstructure properties of UNS G10400 carbon steel was investigated. The UNS G10400 samples, were cut to the desired dimensions, welded by means of electric metal arc welding process and subjected to PWT, at 550ºC, 650ºC, and 700ºC, for 1 h, respectively. The samples were immersed in seawater environment and its corrosion resistance and microstructure properties were then evaluated, using gravimetric technique, Open Circuit Potential (OCP), Potentiodynamic Polarization (PDP), Electrochemical Impedance Spectroscopy (EIS) and Scanning Electron Microscope (SEM)/ Energy-Dispersive X-ray Spectroscopy (EDX), respectively. The findings show that the post-weld tempered (PWT) samples exhibited higher corrosion resistance compared to the as-welded samples. The corrosion rate values are 0.1351, 0.06331, 0.06271 and 0.01578mm/year for as-welded, PWT-5500C, PWT-6500C and PWT-7000C samples respectively. The SEM/EDX images of PWT samples revealed an increased in grain size, forming a tempered martensite. These results are due to re-crystallization and grain growth resulting from post-weld tempering. Therefore, an appropriate post weld tempering for UNS G10400 carbon steel welded joints is recommended for advanced industrial applications.

The next step in the evolution of manufacturing will be the implementation of flexible, scalable systems that produce a product in the most favorable environment using the best available tools, techniques, and resources to achieve significant cost savings, increased productivity, and long-term benefits. Through a review of relevant literature and a series of case studies, this study assessed the efficiency of sustainable manufacturing at the plant and line levels.The study's basis was the influence of economic, social, and environmental aspects on manufacturing sustainability. Discussions on the fundamental approaches for analysing the performance of sustainable manufacturing at various production levels had taken place throughout the research. This study also extensively analysed the approaches currently used to analyse sustainable manufacturing performance, and it explored and examined the challenges encountered. These approaches are addressed in this study through a case study of a recycle-friendly automotive aluminium alloy business and production of carbonated bottled drinks. The framework is then used to suggest a thorough set of approaches for analysing sustainable manufacturing at the plant and production line levels.