Elliptic Confidence on Correspondence Analysis Stainless Steels Corrosion Problem

Stainless steel is the primary material of the lowerside superheater (LSSH) convection pipe support for petroleum or natural gas. Stainless steel corrosion is a severe challenge in equipment maintenance and operation. Corrosion may cause structural defects, leaks, and even failures in superheater convection pipes that could disrupt production and lead to reduced product quality. The Sigma phase occurrence is an indicator of the existence of stainless-steel corrosion. This corrosion occurs due to the exposure of steel to extremely high temperatures over a long period. The experiment was conducted on ASTM A297 after 24 years of operation. The testing sample was acquired from an Indonesian petrochemical company as part of the LSSH convection pipe support. Specimens of the material were heated at a high temperature over 500 °C. The corrosion process was observed based on the corrosion location and color. To analyze and understand this corrosion problem, correspondence analysis was performed. One statistical technique for examining the relationship between two sets of categorical variables is correspondence analysis. In the context of stainless-steel corrosion, the first variable is corrosion location categorized into three locations: A, B, and C, while the second variable is corrosion color divided into light brown (LBr), dark brown(DBr), bluish blue(BBr), light blue(LBl) and dark blue(DBl). Furthermore, elliptic confidence regions were used to estimate the extent to which points in a two-dimensional space represent different corrosion levels in line with the observed variables. The location and corrosion color of stainless steel are found to be statistically significantly correlated in the results; location A tends to be blue, location B tends to be brown, and location C is uncertain because it depends on whether it is light blue or dark brown. It suggests distribution patterns and identifies areas that are more susceptible to corrosion. These findings assist engineers in making decisions regarding the preservation and maintenance of stainless steel to reduce the corrosion rate.