BS in Materials Engineering
Materials Engineering Department
Chevron Corporation and other refiners face challenges predicting the service life of piping in coker furnaces. This is largely due to a build up coke on a single surface of the piping. This coke build up results in carbon penetration into the surface of the 347 stainless steel used for the pipes. Carbon penetration can lead to degradation of the surface and ultimately, the failure of the pipe. Current modeling software has difficulty predicting the influence of sulfur on the carbon penetration rate. This study aims to provide a baseline for further study into the subject. The carbon penetration rate of 347 stainless steel was investigated at four temperatures ranging from 900°F to 1400°F on a bed of activated charcoal over a period of 100 to 200 hours. It is expected that higher temperatures and longer times will allow for greater diffusion of carbon into austenite, although some chromium carbide may form at the surface. Apart from chromium carbide formation, the carbon absorption into the austenitic matrix should remain a single phase process. Carburization rate was characterized by EDS, metallographic analysis, and microhardness measurements. Results will lead to determination of the non-steady state diffusion coefficient for carbon into 347 stainless steel.