Corrosion and Cracking of Lower Furnace Wall Tubes in Recovery Boilers, 1999 Engineering Conference Proceedings
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Harry Dykstra, Neil Risebrough and Angela Wensley
Cracking of composite tubes in recovery boiler side wall tubes has become an important problem as more mills report the incidence of cracking. These cracks typically stop abruptly at the carbon steel interface but there are a number of incidents where significant cracking into the carbon steel has occurred. Historically, cracking has been found at welds and has been attributed to the thermal fatigue cracking. This paper provides examples of tube corrosion and cracking at smelt spout openings, air ports and wall tubes remote from openings. The influence of corrosion is highlighted in these cases with the objective of showing that thermal fatigue, which denies the relevance of corrosive agents, is not adequate to describe the cracking mechanism(s) active in this environment.