Investigation on Bulging of Blow Pipe in a Blast Furnace
After about a year of uninterrupted service, one of the blow pipes on a blast furnace developed a bulge measuring 300 x 150 x 12 mm. The conical shaped section was removed from the furnace and examined to determine why it failed. The investigation consisted of visual inspection, chemical analysis, microstructural characterization, and mechanical property testing. The pipe was made from nonresulfurized carbon steel as specified and was lined with an alumina refractory. Visual inspection revealed cracks in the refractory lining, which corresponded with the location of the bulge. Microstructural and EDS analysis yielded evidence of overheating, revealing voids, scale, grain boundary oxidation, decarburization, and grain coarsening on the inner surface of the pipe, which also suggest the initiation of creep. Based on the information gathered during the investigation, the blow pipe was exposed to high temperatures when the liner cracked and subsequently bulged out due to creep.
Pankhuri Sinha, Goutam Mukhopadhyay, Sandip Bhattacharyya, Investigation on Bulging of Blow Pipe in a Blast Furnace, Handbook of Case Histories in Failure Analysis, Vol 3, Edited By Larry Berardinis, ASM International, 2019, p 688–694, https://doi.org/10.31399/asm.fach.v03.c9001850
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