Analysis of Selection Standard of Anti-corrosion Material for Vinyl Acetate Production Equipment

in the production process of vinyl acetate, the environment in which the equipment is located is usually highly corrosive, because the production process involves a variety of chemical media, such as acetic acid, acetaldehyde and other acidic or oxidizing substances. These media are easy to cause corrosion to equipment materials, thus affecting production efficiency and equipment life. Therefore, when selecting the anti-corrosion material of vinyl acetate production equipment, it is necessary to comprehensively consider the corrosion resistance, mechanical strength, economy and service life of the material. This paper will discuss the selection criteria of anti-corrosion materials for vinyl acetate production equipment in detail from the aspects of corrosion environment analysis, material selection criteria and practical application cases.

Working Environment and Corrosion Characteristics of 1. Vinyl Acetate Production Equipment

in the production process of vinyl acetate, the equipment usually needs to withstand the combined effects of a variety of corrosion factors, including chemical corrosion, electrochemical corrosion and physical corrosion. Specifically, vinyl acetate production equipment may be exposed to the following corrosive media:

1. acetic acid (CH3COOH) acetic acid is a strong corrosive acidic substance, especially at high temperature.
2. Acetaldehyde (CH3CHO): Acetaldehyde is prone to oxidation at high temperatures, generating highly corrosive substances.
3. Other acidic substances such as sulfuric acid, hydrochloric acid, etc., these acidic substances will accelerate the corrosion process of the equipment.

Due to the existence of the above media, the material of the vinyl acetate production equipment must have excellent corrosion resistance to ensure the long-term stable operation of the equipment.

2. anti-corrosion material selection criteria

1. corrosion resistance In the selection of anti-corrosion materials, we must first consider the corrosion resistance of the material. The material shall be resistant to the corrosive media exposed to during vinyl acetate production. Commonly used corrosion-resistant materials include stainless steel, Hastelloy, titanium alloys, and coating materials.

   Among them, Hastelloy (Hastelloy Alloys) is widely used in vinyl acetate production equipment because of its excellent corrosion resistance. Hastelloy is a nickel-based alloy, which has good acid resistance, alkali resistance, oxidation resistance and other properties, especially under high temperature conditions. Common Hastelloy alloys include Hastelloy B, Hastelloy C, and Hastelloy D, which are suitable for different corrosion environments.

2. Mechanical properties In addition to corrosion resistance, the mechanical properties of the material are also one of the important criteria for selection. Vinyl acetate production equipment usually needs to withstand a certain pressure and temperature, so the material must have sufficient strength and toughness. For example, Hastelloy Hastelloy C has excellent mechanical properties at high temperatures, which can meet the requirements of equipment under high temperature and high pressure conditions.

3. Economy When choosing anti-corrosion materials, it is also necessary to consider the economy of the material. The price of different materials varies greatly, so under the premise of meeting the performance requirements, materials with high cost performance should be selected as much as possible. For example, although the coating material is less expensive, it may not reach the expected service life in some corrosive environments, but will increase the maintenance cost of the equipment.

Application of 3. Hastelloy in Vinyl Acetate Production Equipment

hastelloy is a kind of anti-corrosion material widely used in vinyl acetate production equipment. Here are some typical application scenarios:

1. reactor: The reactor is one of the core equipment for vinyl acetate production, and its internal environment usually contains strong corrosive media. Because of its excellent corrosion resistance, Hastelloy has become the first choice of reactor materials.

2. Pipes and heat exchangers: In the production of vinyl acetate, pipes and heat exchangers need to transport and handle a variety of corrosive media. The corrosion resistance of Hastelloy alloy can effectively prevent the corrosion of pipes and heat exchangers and prolong the service life of equipment.

3. Pumps and valves: Pumps and valves are important fluid conveying components in vinyl acetate production equipment. Since these parts need to be frequently exposed to corrosive media, the corrosion resistance of Hastelloy can ensure its long-term stable operation.

4. the choice of other anti-corrosion materials

in addition to Hastelloy, other anti-corrosion materials are also widely used in vinyl acetate production equipment, such:

1. titanium alloy: Titanium alloy is a kind of light and high strength corrosion resistant material, especially in wet corrosion environment. The processing cost of titanium alloy is higher, so it may be more inclined to choose other materials in some non-critical equipment.

2. Coating materials: coating materials (such as epoxy resin, polyurethane, etc.) can be coated on the surface of the device to form a protective film, so as to isolate the corrosive medium from contact with the substrate material. The cost of the coating material is lower, but its service life and corrosion resistance may not be as good as Hastelloy.

5. summary and suggestions

when selecting the anti-corrosion material of vinyl acetate production equipment, the corrosion resistance, mechanical properties, economy and applicability of the material should be considered comprehensively. Hastelloy, as a nickel-based alloy with excellent performance, has become the preferred anti-corrosion material for vinyl acetate production equipment because of its stable performance under high temperature, high pressure and strong corrosion environment.

It is suggested that suitable materials should be selected according to the specific corrosion environment in practical application, and the corrosion resistance of materials should be verified by experimental tests. It should also combine the operating conditions and maintenance costs of the equipment to formulate a reasonable material selection plan to ensure the long-term stable operation of the equipment and the efficient production.