Metal as one of the most common used materials in industry, needs a proper management for it will not contaminate the land. Metal waste, or also called scrap metals, is disposed in a scrap yard. To prevent the accumulation of scrap metals in the scrap yard area, reducing the generation of it is important. Especially when the auction procedure for scrap metals takes a long time. PLTGU Muara Karang had upgraded GTG 1.3 to Advanced Extendor Combustion System in October 2016 to improve its operational excellence. The impacts of upgrading gas turbine to Advanced Extendor Combustion System, are not only for better efficiency in performance, but also extending the maintenance interval up to 32000 hours. By extending the maintenance interval, combustion inspection, which is usually performed every 8000 hours, can be dismissed. The total maintenance duration needed also reduced from 120 days to 66 days on 8 years period. This leads to reducing metal waste generated during maintenance. By calculating the spare parts that required to be replaced in one combustion inspection, the metal waste reduction potential is 2.26 ton. For 8 years period, the combustor upgrade help to reduce metal waste generation about 75.02%.