Leakage Cause Analysis of Water-Wall Pipe in Subcritical Boiler

In view of the local cracking and leakage water-wall pipe Subcritical Boiler in a thermal power plant, mechanism water wall was studied by means macroscopic analysis, chemical composition metallographic structure, Brinell hardness test, tensile test at room temperature scanning electron microscopy. The results show that there is no misuse materials or unqualified cracked leaked pipe. There are large number corrosion deposits pits on inner pipe, showing obvious characteristics under scale. Compared with position section, tumor products also found, indicating overall section. Corrosion scale causes thickness pipeline to be reduced continuously. pearlite spheroidization microstructure near crack grade 4, holes intergranular cracks can seen. At same time, oxide decarburization layer edge crack, hydrogen making value lower than standard value. Therefore, it inferred main tubes corrosion.