A super-preservation(SP) film for stainless steel has been developed to extend the service life of refinery plant equipment. The surface is based on in-situ chemical and electrochemical modifications of stainless-steel surfaces. X-ray Photoelectron Spectroscopy (XPS) studies have shown that super-preservation film thickness is 100 times that of the natural passivated film. In 6wt% FeCl3 corrosion tests, the corrosion rates were reduced by about an order of magnitude.
This technology is suitable for resisting corrosion caused by chloride ions, sulfur, hydrogen sulfide, and naphthenic acids. It has been successfully applied to internals in refineries for over a decade. We present the applications of super-preservation film in low-sulfur, high-acid crude oil processing units as well as sour crude oil processing units. In Case 1, a Crude Distillation Unit (CDU) processing crude oil with Total Acid Number (TAN) of 3.5-4.5mgKOH/g and sulfur content of 0.23% (wt.), in the high temperature scrubbing section of a vacuum tower, super-preservation treated packing saw a 3 times improvement over conventional packing. In Case 2, in high temperature sulfur-naphthenic acid corrosion conditions, treated 304 and 316L packing both showed a relatively significant increase in corrosion resistance.
