Creation of anticorrosion coatings for contact devices of rectifying columns

Abstract

Today the main corrosion protection methods applied in contact devices of rectifying oil processing equipment, in particular, in mesh nozzles made of stainless steel, under relatively high temperatures (150–250оC) and in the presence of aggressive components in oil raw materials (hydrogen sulfide, sulfides, mercaptans, other sulphurous compounds, chloride ions, organochlorine connections, water) are to use special alloys as protecting covers as well as corrosion inhibitors that reduce corrosion action of hostile environment. At the same time, the disadvantages of the majority of these methods concern high operational costs, insufficient efficiency or protection ability designed only for a certain factor, but not for combination of them. In this regard corrosion resistance of mesh contact devices made of stainless steel (brand SUS 321) has been studied on three types of samples: alloy wire, welded grid, thin leaf. Titanium nitride (TiN) and metallic coatings from nickel (Ni), titanium (Ti) and chrome (Cr) were used as anticorrosion coatings for the mentioned samples. These coverings were applied on samples in two ways: by means of electrolytic method and vacuum ion-plasma dusting. It was determined that optimal coating thickness is 10–15 microns as it is the thickness at which the produced films possess sufficient plasticity and do not exfoliate from the surface of the corresponding corrosion-proof alloy. The research of corrosion of samples of stainless steel SUS 321 with applied coverings and without them was performed by immersing the samples into compositions that contain oil as well as into the modeling hostile oil-containing environment. As a result of the conducted researches it was determined that the protecting covers of chrome and titanium nitride applied with vacuum ion-plasma dusting method are the most effective coatings from the point of view of anticorrosive protection for mesh contact devices of stainless steel used in rectifying columns.

Keywords

• rectifying column
• mesh contact devices
• stainless steel
• hostile environment
• corrosion inhibitors
• anticorrosion protecting covers