Routine inspections of a carbon steel wood pulp digester revealed a sharply increasing number of cracks in the overlay metal on the internal surface of the digester after 1 and 2 years of service. The weld overlay was composed of type 309 stainless steel on the top fourth of the digester and of a proprietary high-nickel material on the bottom three-fourths. Examination revealed three distinct modes of deterioration. General corrosion was linked to the use of unspecified overlay metal. Cracking resulted during installation from the use of a material susceptible to hot cracking. Deep corrosion fissures then developed at hot crack sites as a result of crevice corrosion. Use of the appropriate overlay material was recommended.
Robert D. Port, Corrosion and Cracking of the Internal Surfaces of a Black Liquor Digester, Handbook of Case Histories in Failure Analysis, Vol 1, Edited By Khlefa A. Esaklul, ASM International, 1992, p 128–131, https://doi.org/10.31399/asm.fach.v01.c9001049
Download citation file: