Gray-Iron Paper-Drier Head Removed from Service
A paper drier head manufactured from gray cast iron was removed from service as a result of NDE detection of crack-like surface discontinuities. This component was subjected to internal steam pressure to provide heat energy for drying. Investigation (visual inspection, chemical analysis, mechanical testing, as-polished 54x magnification, etched with nital 33x/54x/215x/230x magnification) supported the conclusions that the NDE indications were the consequence of a cold-shut condition in the casting. The cold shut served as a stress-concentration site and was therefore a potential source of crack initiation. The combination of low material strength and a casting defect was a potential source of unexpected fracture during service, because the component was under pressure from steam. Recommendations included removing other dryer heads exhibiting similar discontinuities and/or material quality from service.
Gray-Iron Paper-Drier Head Removed from Service, ASM Failure Analysis Case Histories: Pulp and Paper Processing Equipment, ASM International, 2019, https://doi.org/10.31399/asm.fach.pulp.c0089567
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