Some of the admiralty brass tubes were failing in a heat exchanger. The heat exchanger cooled air by passing river water through the inside of the tubes. The wall thickness of all tubes ranged between 1.19 to 1.27 mm (0.047 to 0.050 in.). General intergranular corrosion occurred at the inside surfaces of the tubes. Transgranular stress-corrosion cracking, probably the result of sulphates under basic conditions, and dezincification occurred also as the result of galvanic corrosion under the deposits in the tubes. Recommendations were to use a closed-loop water system to eliminate sulphates, ammonia, etc., and to run trials on one unit with tubes of other alloys such as 80-20 Cu-Ni or 70-30 Cu-Ni to evaluate their performance prior to any large scale retubing operations.
Philip J. Kenny, Stress-Corrosion Cracking and Galvanic Corrosion of Admiralty Brass, ASM Failure Analysis Case Histories: Power Generating Equipment, ASM International, 2019, https://doi.org/10.31399/asm.fach.power.c9001651
Download citation file:
Join ASM International
Being a member of the world’s largest association of materials professionals provides the benefits and resources you need to accomplish your personal and professional goals.