Estimation of Metal Loss by Corrosion Process in Heat Exchangers Applied to Hydrotreating Systems

Abstract

It is well known that among of all the components of hydrotreating systems used in the industrial processes, the heat exchangers that pre-heat the reactor suffer the greatest degree of degradation by pitting corrosion due to extreme temperature exposure. Typically, two different mathematical analysis were used to estimate the probability of failure by metal loss as a consequence of pitting corrosión mechanism: short-term and long-term corrosion rate (STCR and LTCR, respectively), as designated by API 510 standard method. However, the results are often misunderstood when the difference between the calculated data of STCR and LTCR is large. For this reason, in this research the STCRs and LTCRs models were fitted to a generalized extreme value distribution (GEVD) to characterize the metal loss that take place in four heat exchangers, as well as to determine what kind of corrosion rate model is better for predicting the metal loss estimation. According to the results obtained in this research, the STCR model appears to be the most appropriate analysis for estimating future metal loss by pitting corrosion for the heat exchangers reactors used in hydrotreating systems.