Engineers from Exponent, Menlo Park, Calif., pointed out in a presentation at MS&T 2019 that although stainless steel is resistant to general corrosion, the failure analysis of a stainless steel hot water heater shows that it could be susceptible to other modes of corrosion.
Hot water heaters constructed from carbon steel for domestic use commonly have a limited lifetime due to corrosion susceptibility in municipal tap water. Corrosion mitigation techniques include coatings and cathodic protection to reduce the rate of corrosion or prevent exposure of the underlying steel to the aqueous environment.
A limited number of manufacturers produce hot water heaters from more corrosion-resistant materials such as austenitic stainless steels. Although these alloys are designed to be more resistant to general corrosion, they tend to be more susceptible to other modes of corrosion, such as localized corrosion and stress corrosion cracking.
During normal operation, a stainless steel indirect hot water heater started leaking after approximately 25 years of service. This presentation details the failure analysis that was conducted to evaluate the mode and cause of failure.
Title: Failure Analysis of a Corrosion Resistant Hot Water Heater
Authors: Noah Budiansky, Vir Narinkari, Ockert Van Der Schijff, Exponent Inc.
https://www.matscitech.org/MST19/TechnicalProgram
