An SB407 alloy 800H tube failed at a 100 deg bend shortly after startup of a new steam superheater. Three bends failed and one bend remote from the failure area was examined. Visual examination showed that the fracture started on the outside surface along the inside radius of the bend and propagated in a brittle, intergranular fashion. Chemical analysis revealed that lead contamination was a significant factor in the failure and phosphorus may have contributed. The localized nature of the cracks and minimum secondary cracking suggested a distinct, synergistic effect of applied tensile stress with the contamination. Stress analysis...
Edward J. Franz, Steam Superheater 800H Tube Failure, Handbook of Case Histories in Failure Analysis, Vol 2, Edited By Khlefa A. Esaklul, ASM International, 1993, p 217–221, https://doi.org/10.31399/asm.fach.v02.c9001341
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