Duplex Al-based thermal spray coatings for corrosion protection in high temperature refinery applications

Abstract

The application of thermal spray coatings has been effective in preventing corrosion of steel and iron products. It has been used in a wide range of applications spreading from the petroleum to the food industry. In this work, the performance and effectiveness of a two-layered aluminum-based thermal spray coating applied to an ASTM A387 G11 steel was evaluated. The coating structure was comprised of an inner Al-Fe-Cr layer and an outer layer of aluminum. Coated samples were tested in the reactor zone of a fluid catalytic cracking unit (FCCU) of a petrochemical plant for 2.5 years. The reactor zone temperature was about 793 K (520 °C) and the environment was a mixed gas containing sulfur, oxygen and carbon. Laboratory-scale tests were also conducted on the coated samples in order to gain a better understanding of the corrosive effect of the gaseous species present in the FCCU atmosphere. Porosity present in the thermal spray coatings allowed the penetration of the atmosphere corrodents, which instigated intergranular corrosion of the steel substrate. The presence of an inner Al-Fe-Cr layer did not prevent coating spallation, which further contributed to the internal corrosion process

Corrosion Mechanism and Countermeasures in Oil Refineries - Comprehensive Review

“…It has also been suggested that the amount of Sulphur and naphthenic acid in crude oil has an effect on the rate of corrosion. It has been the subject of extensive research in a number of studies, as shown in Figure (4) [35]. Predicting how naphthenic acid will corrode is hard because of the complex interactions between the type of crude oil, temperature, flow rate, type of alloy, surface state and Sulphur contented [36].…”

Preparation of PMMA/hBN composite coatings for metal surface protection

“…As was described in the previous test with NaCl solution, porosity gives to the ions in solution a free path through the coating, increasing the extent of the acid attack to the polymeric matrix. After some time, the stress in the coating increases and cracks are formed due to the corrosion process started 32 , causing the collapse of the coating, and consequently, weight loss.…”

Sulfidation-Oxidation Resistance of Thermal Diffusion Multi-Layered Coatings on Steels

“…Surface engineering, specifically through the advanced coating formation route, can be considered as an alternative strategy for high-temperature sulfidation and sulfidation-oxidation protection, especially if low-cost steels are used as substrate materials. Different coating materials and technologies for corrosion protection can be listed [ 21 , 22 , 23 , 24 , 25 , 26 ]. However, many coating options either have poor performance at high temperatures or insignificant thicknesses compared to possible structural defects, or poor adhesion and bonding to steel substrates, which leads to detachment issues at elevated temperatures.…”