What corrosion inhibitors can effectively prevent SSCC?

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Considering the background related to the prevention of SCC in liquefied petroleum gas storage tanks, the main types of corrosion inhibitors that can effectively prevent sulfide stress corrosion cracking are as follows; all of these have been tested in practice within the refining industry. First, amine-based corrosion inhibitors – represented by the neutralizing type CT2-13 – are the preferred type as recommended by the NACE standards. They help reduce the corrosivity of the medium, maintaining the pH level within the safe range of 9-11, thereby significantly reducing the penetration of hydrogen atoms into the steel matrix and lowering the susceptibility to SCC at its source. II. Imidazoline-based corrosion inhibitors are the most widely used film-forming corrosion inhibitors in the petrochemical industry. For example, the Vikor® RF series; the nitrogen atoms in the imidazoline ring can form stable coordination bonds with the metal surface, resulting in a dense protective film 5–8 μm thick that prevents H₂S from coming into contact with the steel, thereby effectively suppressing electrochemical corrosion and hydrogen-induced cracking. III. Gas-liquid two-phase composite corrosion inhibitors: Designed for the special environment where gas and liquid coexist in LPG storage tanks, these inhibitors are based on imidazoline derivatives, combined with thiazole and organic amine components. They can achieve a corrosion inhibition rate of over 90% at a low concentration of 80 mg/L, providing corrosion protection for both the gas phase and liquid phase areas of the storage tanks; moreover, they require 38.5% less dosage compared to traditional single-phase corrosion inhibitors. IV. Multipolar gene corrosion inhibitors: By forming a strong adsorption film on the metal surface and using hydrophobic groups to prevent water and hydrogen sulfide from corroding the metal matrix, these are specialized corrosion inhibitors optimized for the conditions in liquefied gas storage tanks; they can significantly reduce the likelihood of SCC occurrence. It should be noted that corrosion inhibitors alone cannot fully control SSCC; they need to be used in combination with measures such as control of material hardness and stress-relief heat treatment to achieve the best preventive effects.