Failure analysis of Incoloy 800 water immersion heating element

Abstract

Driven by regulations and restrictions of using fossil fuels and reducing carbon dioxide emissions, electrical heating is becoming a good choice for many domestic and industrial applications. High temperature oxidation along with corrosivity of the service environment bring many challenges to heating element designers and service engineers. Many factors, including design, overheating, sheath tube failure, corrosion, and overheating, cause heating elements to fail in use. Failure analysis is one method for enhancing a product's performance, reliability, and design.In this paper, a metallurgical failure analysis of Incoloy 800 water immersion heating element was conducted. Optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Vickers microhardness (Hv), and X-Ray radiography were used to analyze the different components of the failed item.Stress corrosion cracking (SCC) was identified as the cause of the failure. The chloride containing water caused the failure to begin by pitting on the Inconel 800 sheath material's outer surface, and then propagated as stress corrosion cracking (SCC).