Issues related to vapor phase corrosion inhibitors

Vapor-phase corrosion inhibitor is a volatile corrosion inhibitor. The gas that evaporates automatically at room temperature can inhibit atmospheric corrosion of metals. Therefore, when using vapor phase corrosion inhibitors, the surface, inner cavity, pipes, grooves and even gaps of metal products can be protected without direct contact with the metal surface. Due to its long anti-rust period, easy operation, and low cost, the research and application of vapor phase corrosion inhibitors and vapor phase corrosion inhibition technology have developed rapidly in recent years. 1. Multi-purpose universal vapor phase corrosion inhibitor. In the past 20 years, vapor phase corrosion inhibitors have been almost always used for the protection of steel and metal materials and products. However, there are varying degrees of corrosion or incompatibility with various non-ferrous metals, so that for non-ferrous metal parts such as copper, zinc, and cadmium in various metal assembly mechanical products, it is often necessary to take isolation protection measures or abandon the use of vapor phase corrosion inhibitor technology. The research and application of multi-efficiency gas-phase corrosion inhibitors that have corrosion inhibition effects on ferrous metals and non-ferrous metals have always been one of the key development directions of gas-phase corrosion inhibitors [1]. 　　In the early 1960s, the anti-tarnishing effect of benzotriazole on brass was confirmed, thus opening the door to the use of vapor phase corrosion inhibitors to protect copper-based materials. Various experimental results show that in addition to excellent corrosion inhibition properties for copper and copper alloys, benzenetriazole also has good corrosion inhibition effects on silver, silver-plated layers, zinc, zinc-plated layers, cadmium-plated layers and other metals. In addition, in recent years, various derivatives of benzotriazole, such as * * Triazole, 3-amino-1.2.4-benzenetriazole, diphenyltriazole, and tetrazole were studied. The results show that the above corrosion inhibitors have good protective effects on zinc, cadmium, lead, nickel, tin, and copper, and also have certain corrosion inhibition effects on steel, magnesium, and aluminum [2]. 1-Hydroxybenzenetriazole (a new type of water-soluble high-efficiency vapor phase corrosion inhibitor) developed by Hunan University not only has good corrosion inhibition properties for brass and copper in neutral or alkaline aqueous solutions, but also has good corrosion inhibition effects on steel and cast iron. This corrosion inhibitor has low toxicity and less pollution. When its aqueous solution concentration is above 0.05%, it has good corrosion inhibition and bacterial growth inhibition effects. When it is used in conjunction with other corrosion inhibitors such as phosphate, the anti-rust performance can be further improved. In addition to benzene triazole and its derivatives, chromate compounds (such as cyclohexylamine chromate, dicyclohexylamine chromate, tert-butyl chromate), o-nitro compounds such as o-nitrophenol dicyclohexylamine, o-nitrophenol triethanolamine, o-nitrophenol tetraethylenepentamine, o-nitrophenol * * * Organic amine salts of formic acid, cinnamate, borate, thioureas, thiazole, and imidazole compounds have certain corrosion inhibition effects on a variety of nonferrous metals and coatings [3]. 　　At present, more than 1/3 of the vapor phase corrosion inhibitor materials reported in the United States, Japan and other countries are general-purpose multi-efficiency vapor phase corrosion inhibitor materials. 2 High-efficiency and low-toxic gas-phase corrosion inhibitors In the research and development process of gas-phase corrosion inhibitors, nitrite once occupied a dominant position, so that in the literature introducing gas-phase corrosion inhibitors in various countries around the world, dicyclohexylamine nitrite is still often represented. Due to its effective long-term anti-rust ability and excellent salt spray resistance for steel products, it is indispensable in anti-rust packaging materials for military equipment and exported mechanical and electrical products. In August 1990, my country conducted an unpacking inspection of firearms sealed with dicyclohexylamine nitrite in 1964. They were still bright and rust-free after 26 years. The storage location included the Sichuan area where the temperature, humidity and salt spray atmosphere were relatively high. 　　However, the toxicity of nitrite has attracted more and more attention. Entering the 21st century, driven by sustainable development strategies, the development of low-pollution, non-polluting gas phase corrosion inhibitors will be a top priority. The international environmental standards ISO 14000 have been successively promulgated and implemented since 1996. Now many * * It is stipulated that MSDS (Material Safety Data) must be attached when purchasing gas-phase corrosion inhibitor materials, so great attention must be paid to the research and application of high-efficiency and low-toxicity gas-phase corrosion inhibitors. 　　The American company CORTECCORPRATION, which has been widely reported recently, said that after 20 years of development, it has become the world leader in vapor phase rust prevention technology. The company researches and produces more than 10 series of more than 200 efficient and non-polluting vapor phase corrosion inhibitor technologies and products, including metal cutting fluids, grinding fluids, cleaning agents, rust inhibitors, vapor phase anti-rust paper, and vapor phase anti-rust films containing vapor phase corrosion inhibitors ( It has both electrostatic shielding and electrostatic dissipation functions), vapor phase anti-rust tablets, pills, lozenges, powders, liquids, aerosols, etc., and has been recognized by the U.S. military and the U.S. Drug and Food Administration (FDA). The company's products have been sold in more than 70 countries around the world. * * It has been widely promoted and applied. 　　The high-efficiency, low-toxicity and high-stability vapor phase corrosion inhibitors for steel reported abroad are mostly imidazole compounds, such as 2-methylimidazole, 2-ethyl-4-methylimidazole and 2-isopropylimidazole. They have excellent anti-rust properties and can meet the US military standard MIL-I-22110. Thermal stability is as high as 250 ℃, low toxicity, and LD50 is 1 500 to 3 000. mg/kg, has no harmful physiological toxicity to the human body and can be degraded by bacteria. They can be extracted from by-products of the vitamin B6 production process at low cost. 　　Japan has recently reported a general-purpose vapor phase corrosion inhibitor with good anti-rust effect on a variety of metals. The representative ones are 1,2,4-triazole and its derivatives. It has good anti-rust effect on more than 10 kinds of metals and their alloys including steel, iron, copper, silver, aluminum, zinc, nickel, tin, cadmium, magnesium, lead and their alloys in various atmospheres. It is non-toxic, has high solubility in water and good stability. Such as 4-H-1,2,4-triazole, 4-H-3,5-dimethyl-1,2,4triazole, etc. According to data reports, the LD50 of 3-amino-1,2,4-triazole is 14 700 mg/kg. Many domestic colleges and universities and scientific research institutes such as East China University of Science and Technology have also been committed to the research of high-efficiency and low-toxic gas phase corrosion inhibitors in recent years. The advancement of organic synthesis technology enables people to design and synthesize new gas phase corrosion inhibitors based on the structure-activity relationship of corrosion inhibitors. The research and development of oligomeric corrosion inhibitors is the development direction of high-efficiency and low-toxic gas phase corrosion inhibitors. The corrosion inhibitor molecules contain 2 or more active units. Oligomers are different from polymers. They have a certain ability to dissolve and evaporate, and have a large coverage area on the metal surface. The synergistic effect between various active groups in the molecule can * * Improve its corrosion inhibition ability. Generally speaking, polymers are less toxic than their monomers and have better compatibility with various carriers. Under the guidance of this molecular design concept, oligomeric corrosion inhibitors with two or more functional groups have been released one after another [4], such as amino, hydroxyl, alkyl, nitro, etc. A new type of gas-phase corrosion inhibitor made from extracts from the by-products of synthetic fatty acids and alkyl and amino low polymers has excellent corrosion inhibition performance and low toxicity. After toxicity tests conducted by medical and health institutions, its LD50 was 8 968 mg/kg and 9 013 mg/kg respectively, which falls within the actual non-toxic range [5]. 3 Development and selection of mixed multi-component gas phase corrosion inhibitors Gas phase corrosion inhibitors must meet the two most basic conditions, that is, they should contain one or more corrosion inhibitor groups in their components, and they must have appropriate vapor pressure. If the vapor pressure is too low, the corrosion inhibitor gas cannot saturate the packaging space in a short period of time, which may cause initial corrosion. ； If the vapor is too high, the corrosion inhibitor gas will lose too quickly and a long-lasting anti-rust period cannot be achieved. This requires the mixing of two or more corrosion inhibitors with different vapor pressures. For example, the vapor pressure of dicyclohexylamine nitrite is 0.016 Pa at 21°C, while the vapor pressure of cyclohexylamine carbonate is 53 Pa at 21°C. The mixed use of the two can complement each other, which can not only provide long-term rust prevention, but also shorten the time for the corrosion inhibitor atmosphere to reach equilibrium. 　　At present, mixed vapor phase corrosion inhibitors are mainly used to prevent rust of various metal assemblies. However, it should be pointed out that the mixed gas-phase corrosion inhibitor selected at this time should have a close vapor pressure, otherwise it will cause incompatible metal corrosion due to premature volatilization of a certain component of the gas-phase corrosion inhibitor. Taking the composite metal of steel and brass as an example, if benzene triazole is used as a corrosion inhibitor for copper, it cannot protect the steel at the same time. If other gas phase corrosion inhibitors are selected, it may promote the corrosion of copper. Therefore, similar volatilization degrees must be considered so that the two gas-phase corrosion inhibitors can be preferentially adsorbed on the surface of special metals within a relatively close time to achieve a better synergistic effect and avoid adverse effects as much as possible. So far, almost all of the multi-efficiency vapor phase corrosion inhibitor components reported at home and abroad for multi-metals are mixed gas phase corrosion inhibitors. Therefore, mixed gas phase corrosion inhibitors are still the key research and development direction of gas phase corrosion inhibitors in the future. 4 Multi-carrier applied vapor phase corrosion inhibitors Regarding the application forms of vapor phase corrosion inhibitor technology, there are more than 10 foreign reports, mainly including: 　　(1) Powder method: Put the vapor phase corrosion inhibitor powder into gauze or non-woven bags or directly spread it on different parts of the mechanical equipment. The dosage and effective distance vary with different brands. ； 　　(2) Tablet, Pill, and Tablet Method Mix the gas-phase corrosion inhibitor with an appropriate amount of binder and active material, and press it into tablets, pills, and tablets of different shapes. The usage method is the same as the powder bag method. ； 　　(3) The aerosol method places the gas-phase corrosion inhibitor in a device composed of a reservoir, a heater and a fan. The aerosol or smoke generated by it can condense on the metal surface, while the excess gas-phase corrosion inhibitor is discharged and circulated repeatedly. ； 　　(4) Foam particle method: The gas phase corrosion inhibitor and foaming material are made into foam particles or the gas phase corrosion inhibitor solution is soaked in molecular sieve, montmorillonite or silica gel desiccant, and after drying, it is placed in metal products to prevent rust. ； 　　(5) Vapor phase synthesis method: The raw materials for manufacturing gas phase corrosion inhibitors are used in an environment that needs protection to create a gas phase corrosion inhibitor atmosphere according to the principle of the gas phase synthesis method. This method is suitable for rust prevention of metal walls in the inner cavity of products ； 　　(6) Vapor phase anti-rust water is suitable for immersion or spraying between machining processes to prevent rust. ； 　　(7) The vapor phase anti-rust oil method is suitable for anti-rust of gear boxes and internal combustion engine cylinders. ； 　　(8) Paper (cloth) carrier method This is a more commonly used form at home and abroad. ； 　　(9) After being treated with a gas phase corrosion inhibitor by the gas phase thin film method, the film is made to be transparent, flexible, heat sealable, and has the characteristics of both contact and gas phase rust prevention. In recent years, foreign countries have gradually developed into 2-layer and 3-layer vapor phase films. The inner layer or middle layer is rich in multi-component vapor phase corrosion inhibitors, and the outer layer is transparent, airtight, and watertight [6] ； 　　(10) Peelable vapor phase anti-rust adhesive tape is coated with a layer of silicone and anti-adhesive agent on one side of the base material, and a layer of pressure-sensitive adhesive containing vapor phase corrosion inhibitor is coated on the other side. It will not fall off by itself when attached to the metal surface. It can prevent rust and scratches on the metal surface [7]. 5 Test methods and standards Although the United States promulgated military standards and federal standards for vapor phase corrosion inhibitors and various vapor phase corrosion inhibitor materials treated with vapor phase corrosion inhibitors as early as the early 1950s, Japan used vapor phase corrosion inhibitor technology extensively in the late 1950s. It also formulated a variety of related standards for vapor phase corrosion inhibitor materials and test methods, and revised or revised them every 3 to 5 years. In the early 1980s, my country began to formulate and promulgate industry standards for relevant departments with reference to advanced foreign standards, which played a positive role in promoting the research and development of vapor phase corrosion inhibitor materials and technologies. However, up to now, the performance evaluation, testing instruments and methods of vapor phase corrosion inhibitors have not changed much over the years, and the testing cycle is also long, which is not conducive to the needs of guiding modern large-scale production. This puts our hope in the near future, using advanced modern instruments, technologies and means to develop some fast, accurate and complete performance evaluation test instruments. It is reported that scientific research institutions of some domestic universities are starting to develop it. At present, rapid screening tests for steel and iron materials have achieved results, and it is expected that there will be substantial breakthroughs in the 21st century. 6. Research on the corrosion inhibition mechanism of gas-phase corrosion inhibitors. Optimal deployment of the vapor pressure of mixed gas-phase corrosion inhibitors. Research on the effective action distance of gas-phase corrosion inhibitors. With a variety of non-ferrous metals and coatings, with various plastics, rubber, paints, wood, grease, glass ceramics, adhesives, etc. * * Issues such as the adaptability or compatibility of non-metallic materials such as desiccants and desiccants still require in-depth and systematic research. 　　Over the past 50 years since the founding of the People's Republic of China, especially the 20 years of reform and opening up, we have experienced * * “"Six Five",“ * * ”, the "Eighth Five-Year Plan" scientific and technological research plan, the variety, specifications, technology and quality of my country's vapor phase corrosion inhibitor materials have been greatly developed and improved. Some are equivalent to the level of the US military's P series and Japan's NP series, but the overall level is comparable to that of developed countries abroad. * * There is still a certain gap. In order to accelerate scientific and technological progress and adapt to the needs of the socialist market economy, an industrial structure integrating teaching, scientific research, and production that integrates industry, academia, and research will surely promote the faster development of my country's vapor corrosion inhibitor technology. ［1］Zeng Zhaomin. Rust prevention［M］.Beijing: National Defense Industry Press, 1978. [2] Xiao Huaibin. Overview of the application of gas phase corrosion inhibitors [J]. Shanghai Paper, 1982(3) [3] Xiao Huaibin. An overview of the pros and cons of nitrite anti-rust additives [A]. Proceedings of the Third National Anti-rust Technology Symposium [C]. [Unknown publication], 1995. [4] Xu Wencai et al. Anti-rust packaging technology [J]. China Packaging, 1998, 18(1) [5] Zhang Daquan, Gao Yingfa, Lu Zhu. Green packaging and vapor phase anti-rust technology [J]. China Packaging, 1998, 18(4) [6] Sanrong Chemical Industry Co., Ltd. Heat-sealable high-efficiency vapor phase anti-rust film [J]. Anti-corrosion management (Japan), 1990, 34(4) [7] Horimasa. Corrosion inhibition effect of 3-amino-1,2,4triazole [J]. Anti-corrosion management (Japan), 1990, 34(1)

I have many articles like this. . I would like to know about the effect and cost of adding corrosion inhibitors during natural gas pipeline transportation. How much does it cost to operate in a year? .

Give it a thumbs up! Do you know about the internal corrosion problem of natural gas pipelines? For example, the calculation of the dosage of corrosion inhibitor. wait. .

This post was last edited by Litao1314 at 2011-11-3 12:55 with reply 4# yfc1981 can communicate! Can provide vapor phase corrosion inhibitor series products