Catastrophic Effect of Leak from Condenser and its influence in Remaining life of Superheater Boiler Tube SA 213 T91

This study was conducted to analyze the effects of condenser leakage in a boiler and its impact on the remaining lifespan of the final superheater tube. The tube is of the SA 213 T91 type, which has been in operation for approximately 13 years or over 100,000 equivalent operating hours (EOH). It is an alloy steel composed of chromium (Cr) and molybdenum (Mo), known for its excellent mechanical and thermal properties at high temperatures, as well as its resistance to corrosion. Due to the poor quality of the boiler feedwater, contaminated by seawater because of condenser leakage, the tube experienced corrosion and deposit formation inside. Research includes an examination of the log sheet for boiler water quality, visual inspection of the tube's inner surface, chemical composition testing, thickness testing, tube diameter testing, and creep rupture testing. The analysis of water quality data shows a decrease in pH levels and an increase in chloride (Cl) concentration. Creep testing and the remaining life prediction of the tube, using the Larson-Miller parameter equation for the material, 30.530 = T (30 + log Tr) 10⁻³, indicate that for every 10°C increase in temperature, the remaining lifespan of the tube decreases significantly. For instance, if the metal tube temperature is at 570°C, its actual remaining lifespan is estimated to be 119.53 years, whereas at 580°C, the remaining lifespan drops to 44.97 years. These calculations demonstrate that creep void propagation at high temperatures occurs rapidly, leading to a significantly reduced rupture time of the material.