Reasons for leakage of boiler water cooled wall pipe in thermal power units

A leakage occurred in the water cooled wall pipe of a power plant boiler, causing the unit to shut down. The reasons for the leakage of water cooled wall pipes were analyzed using methods such as macroscopic observation, chemical composition analysis, mechanical property testing, metallographic examination, scanning electron microscopy analysis, outer diameter and wall thickness measurement. The results show that the end and root of the fin notch of the water cooled wall tube had a sharp shape and did not undergo a smooth transition. Stress concentration occurred at this point, and the boiler was subjected to alternating stress and vibration caused by structural loosening during operation. Cracks initiated and continued to expand at the stress concentration point, ultimately led to leakage of the water cooled wall tube.