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This post was last edited by Shaobin Fluid on 2026-3-17 at 12:03. Industrial valves, as key control components in the process industry, are widely used in fields such as chemicals, pharmaceuticals, and metallurgy, performing important functions such as blocking, regulating, and diverting fluids. However, in actual production operations, valves are exposed to harsh conditions such as high temperatures, high pressures, severe corrosion, and high flow rates for extended periods of time, which poses serious challenges to their reliability. Unplanned shutdowns caused by corrosion-induced failure of industrial valves are a significant issue in chemical, pharmaceutical, and metallurgical processes. Analysis of the corrosion failure mechanism of valves: The failure of industrial valves is usually not the result of a single factor, but rather the outcome of the combined effect of chemical corrosion by the medium and physical erosion by the fluid. Main types of corrosion: According to NACE standards, in conditions where corrosion and erosion occur simultaneously, the total material loss (T) is generally greater than the sum of the loss due to corrosion alone (C) and the loss due to erosion alone (E): T = C + E + S, where S represents the loss resulting from the synergistic effect. Under certain high-speed operating conditions with strong acids, S can account for 30%-50% of the total loss. This means that merely improving the corrosion resistance of the material without enhancing surface hardness or adhesion often fails to completely resolve failure issues. The main types of corrosion in industrial valves and the valves most prone to it. The following are the valve types that are most susceptible to corrosion under typical conditions in the chemical and pharmaceutical industries: control valves/regulation valves. High pressure differences resulting from throttling cause a sharp increase in local flow velocities, which makes cavitation very likely to occur. The collapse of steam bubbles generates microjet impacts, and combined with the corrosion by a strong acidic medium, honeycomb pitting is formed. The typical failure cycle for 316L material is 6-12 months. In ball valves, the sphere and the sealing surface of the valve seat being constantly exposed to the medium can lead to pitting and crevice corrosion. In the presence of concentrated hydrochloric acid or chloride ions, the sealing surface fails rapidly, resulting in internal leakage. In gate valves, the channels in the valve disc are prone to the accumulation of medium, leading to crevice corrosion and intergranular corrosion. Under high temperature and pressure conditions, the corrosion rate at the junction between the valve seat and the valve body increases significantly. In butterfly valves, the fluid erosion in the area where the butterfly disc rotates at high speeds is severe; combined with corrosion, this can lead to erosion-corrosion combined damage, especially in environments containing solid particles or highly oxidizing media. Carbon steel/conventional stainless steel valves (304/316L) have insufficient corrosion resistance in their base material; in media such as hydrochloric acid, sulfuric acid, and aqua regia, the corrosion rate can reach 0.5–2.0 mm/year. These valves face the highest risk of corrosion in applications such as pharmaceutical API synthesis, fine chemical reactions, and oil refining. Tantalum surface alloy coating technology: A corrosion protection solution for various valve products. Tantalum surface alloy valves utilize surface alloying techniques (CVD/CVI deposition processes) to form a uniform layer of pure tantalum atoms (50–200 μm) on the surface of the nickel alloy substrate. This technique does not alter the original structure and strength of the valve, but it endows the surface with all the properties of tantalum metal. It can be widely applied to the following valve products: Control valves – coating of the valve core, seat, and throttle sleeve throughout their internal cavities, providing effective protection against cavitation erosion and corrosion. Ball valve: sphere, valve seat sealing surface coating to prevent pitting and internal leakage. Globe valve: Valve disc, valve seat, and flow channel coatings in the valve body to eliminate the risk of crevice corrosion. Butterfly valve: Coating on the contact area between the butterfly disc and the valve body to enhance erosion resistance. Stop valves, check valves, diaphragm valves: custom-coated full flow channels to meet the requirements of various operating conditions. Core protection mechanism: Self-healing titanium film layer (2-5 nm thick), with a corrosion rate close to 0 in the presence of strong acids (hydrochloric acid, sulfuric acid, nitric acid, aqua regia). It completely prevents the ion release from the substrate; the leaching amount of heavy metals is 50 MPa, and it does not detach under thermal shock or mechanical impact. The cost is only 1/5 to 1/3 of that of pure tantalum valves, and their service life is extended several times. Data on the typical medium corrosion rate of tantalum materials. Conclusion: The failure of industrial valves is mostly due to the combined effect of corrosion and erosion; merely improving the corrosion resistance of the material is not sufficient to address all problems. Experimental data show that the corrosion rate of the alloy layer on the tantalum surface in a strong acid environment is below 0.01 mm/y, and its resistance to cavitation is superior to that of pure tantalum. Field application data show that this technology can significantly extend the service life of valves and reduce the risk of metal ion contamination in the products. Economic analysis shows that under highly corrosive conditions, the life-cycle cost of the tantalum surface alloy solution is lower than that of 316L and Hastelloy. Statement: This article was first published on the WeChat official account; the original title is “Corrosion Failure Analysis of Industrial Valves and the Application of Tantalum Surface Alloy Coatings for Corrosion Prevention”. The intellectual property rights related to the content of this article belong to this service account or its rightful owners. 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