Comprehensive analysis of corrosion failure of blast furnace gas pipeline in a steel plant
Tianqi Chen, Liang Sun, Qing Li, Chao Liu, Zhiyong Liu, Xuequn Cheng, Xiaogang Li
Abstract
The corrosion failure of blast furnace gas pipeline made of Q235 carbon steel in a steel plant was investigated. Macro and micro morphology, thickness loss rate and phase composition of rust layer have been comprehensively studied. The macro and micro morphology of failed tube in service for 3.5 years were observed by laser scanning confocal microscope (LSCM), scanning electron microscope (SEM) and energy disperse spectroscopy (EDS), and chemical composition of on-site condensed water and materials was examined. Results indicated that Cl is enriched on the surface of loose corrosion products, which is composed of FeOOH and Fe 2 O 3 . Large thickness loss rate and corrosion gully or holes suggest that mechanism of pitting corrosion are acid chemical corrosion and electrochemical corrosion.