The Pandia digester is a long cylindrical vessel which uses alkaline sulfite liquor to cook sawdust for pulping. The inlet cone was fabricated from AISI 304L stainless steel with E308 welds. Typical liquor concentration was approximately 80% NaOH, 20% Na2SO3 with chloride concentrations at 2 grams per liter. The operating pressures in the inlet cone were up to 1.2 MN/sq m (170 psig). The inlet cone had developed leaks within a year of service. Liquid penetrant inspection showed significant through-wall cracking near the fillet welds joining the bottom flange and side wall and the butt welds. Metallographic specimens were...
D. G. Chakrapani, Stress-Corrosion Cracking of a Pandia Digester Inlet Cone, ASM Failure Analysis Case Histories: Pulp and Paper Processing Equipment, ASM International, 2019, https://doi.org/10.31399/asm.fach.pulp.c9001562
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