To Deal With Liquid Cooling Butterfly Valve Corrosion Problems, Remember These Nine Anti-corrosion Tips!
Corrosion is a major factor contributing to Butterfly Valve cooling damage. Therefore, cooling Butterfly Valve corrosion protection is a crucial consideration in cooling water Butterfly Valve protection. How should Butterfly Valve data center corrosion be protected? Here are nine tips for corrosion prevention!
1. Select corrosion-resistant materials based on the corrosive medium
In actual production, media corrosion is extremely complex. Even for cooling Butterfly Valve made of the same material, the media's concentration, temperature, and pressure can affect the material differently. For every 10°C increase in media temperature, the corrosion rate increases by approximately 1-3 times. Media concentration significantly influences cooling water Butterfly Valve material corrosion. For example, lead exhibits minimal corrosion in low-concentration sulfuric acid, but corrosion increases dramatically when the concentration exceeds 96%. Carbon steel, on the other hand, exhibits severe corrosion at sulfuric acid concentrations around 50%, but corrosion decreases sharply when the concentration increases above 6%. Aluminum is highly corrosive in concentrated nitric acid with a concentration above 80%, but corrosion is more severe in medium and low concentrations. Although stainless steel exhibits strong corrosion resistance in dilute nitric acid, corrosion is exacerbated in concentrated nitric acid above 95%. As the examples above demonstrate, the correct selection of Butterfly Valve cooling materials requires careful consideration of specific circumstances, analysis of various factors influencing corrosion, and reference to relevant anti-corrosion manuals.
2. Using Non-metallic Materials
Non-metallic materials offer excellent corrosion resistance. As long as the water cooling Butterfly Valve's operating temperature and pressure meet the requirements for non-metallic materials, they can not only address corrosion issues but also conserve precious metals. cooling Butterfly Valve bodies, bonnets, linings, and sealing surfaces are often made of non-metallic materials. Gaskets and fillers are primarily made of non-metallic materials. water cooling Butterfly Valve linings are typically made of plastics such as polytetrafluoroethylene (PTFE) and chlorinated polyether, as well as rubbers such as natural rubber, neoprene, and nitrile rubber, while the cooling water Butterfly Valve body and bonnet are typically constructed of cast iron or carbon steel. This ensures both Butterfly Valve cooling system strength and corrosion resistance. Pinch water cooling Butterfly Valve are also designed based on rubber's excellent corrosion resistance and exceptional flexibility. Currently, plastics such as nylon and polytetrafluoroethylene, as well as natural and synthetic rubbers, are increasingly being used to create various sealing surfaces and rings for various valves. These non-metallic materials used as sealing surfaces not only have good corrosion resistance but also good sealing performance, and are particularly suitable for use in media with particles. Of course, their strength and heat resistance are relatively low, and their scope of application is limited. The emergence of flexible graphite has enabled non-metallic materials to enter the high-temperature field, solving the long-standing problem of packing and gasket leakage, and is also a good high-temperature lubricant.
* Commonly used non-metallic materials for applicable working conditions
3. Metal surface treatment
(1) Valve connection
Valve connection screws are often treated with galvanizing, chromium plating, and oxidation (blueing) to improve their resistance to atmospheric and medium corrosion. In addition to the above treatment methods, other fasteners are also treated with phosphating and other surface treatments depending on the situation.
(2) Sealing surfaces and small-diameter closing parts
Surface processes such as nitriding and boronizing are often used to improve their corrosion resistance and wear resistance. The valve disc made of 38CrMoAlA has a nitriding layer ≥0.4mm. (3) Anti-corrosion of valve stems
Surface treatment processes such as nitriding, boronizing, chrome plating, and nickel plating are widely used to improve its corrosion resistance, corrosion resistance, and wear resistance. Different surface treatments should be suitable for different valve stem materials and working environments. For valve stems in contact with the atmosphere, water vapor medium, and asbestos packing, hard chrome plating and gas nitriding processes can be used (stainless steel should not use ion nitriding processes); valves in hydrogen sulfide atmospheres use electroplated high-phosphorus nickel coatings for better protection; 38CrMoAlA can also resist corrosion by ion and gas nitriding, but hard chrome plating is not suitable; 2Cr13 can resist ammonia corrosion after quenching and tempering, and carbon steel using gas nitriding can also resist ammonia corrosion, while all phosphorus nickel coatings are not resistant to ammonia corrosion; 38CrMoAlA material has excellent corrosion resistance and comprehensive performance after gas nitriding, and it is mostly used to make valve stems.
(4) Small-diameter valve bodies and handwheels
Often chrome plating is used to improve their corrosion resistance and decorate valves. 4. Thermal Spraying
Thermal spraying is a process for applying coatings and has become a new technology for surface protection. Most metals and their alloys, metal oxide ceramics, metal-ceramic composites, and hard metal compounds can be coated on metal or non-metal substrates using one or more thermal spraying methods. Thermal spraying can improve surface corrosion resistance, wear resistance, and high-temperature resistance, thereby extending service life. Thermal spraying of special functional coatings offers special properties such as thermal insulation, electrical insulation (or anti-electrostatic), abradable seals, self-lubrication, thermal radiation protection, and electromagnetic shielding. Thermal spraying can also be used to repair components.
5. Spray Coatings
Coatings are a widely used corrosion protection method and are an indispensable anti-corrosion material and identification mark on valve products. Coatings are also non-metallic materials. They are typically formulated with synthetic resins, rubber slurries, vegetable oils, solvents, and other ingredients. They are applied to metal surfaces to isolate them from the medium and atmosphere, achieving their corrosion protection purpose. Coatings are primarily used in less corrosive environments such as water, salt water, seawater, and air. The interior of valves is often painted with anti-corrosion paint to prevent corrosion from media such as water and air. The paint is mixed with different colors to indicate the material used. Valves are typically sprayed with paint every six months to one year.
6. Adding Corrosion Inhibitors
Corrosion inhibitors control corrosion by promoting battery polarization. They are primarily used in media and packings. Adding corrosion inhibitors to media can slow corrosion of equipment and valves. For example, chromium-nickel stainless steel in oxygen-free sulfuric acid undergoes a pyrolysis state over a wide solubility range, resulting in severe corrosion. However, adding a small amount of an oxidizing agent, such as copper sulfate or nitric acid, can convert the stainless steel to a passive state, forming a protective film on the surface that resists the attack of the media. In hydrochloric acid, adding a small amount of an oxidizing agent can reduce corrosion of titanium. Water is often used as the test medium for valve pressure testing, which can easily cause valve corrosion. Adding a small amount of sodium nitrite to the water can prevent water-induced corrosion.
7. Electrochemical Protection
There are two types of electrochemical protection: anodic protection and cathodic protection. For example, if zinc is used to protect iron, it corrodes. Zinc is called a sacrificial metal. In production practice, anodic protection is less common, while cathodic protection is more common. Cathodic protection is used for large and important valves, offering an economical, simple, and effective method. Adding zinc to asbestos filler to protect the valve stem also falls under cathodic protection.
8. Controlling the Corrosive Environment
The term "environment" has both a broad and narrow meaning. The broad definition of "environment" refers to the surroundings of the valve installation and the media flowing through it; the narrow definition of "environment" refers to the conditions surrounding the valve installation. Most environments cannot be controlled, and production processes cannot be arbitrarily altered. Environmental control measures should only be employed when they do not harm the product or process, such as deoxygenating boiler water or adjusting pH with alkali in oil refining processes. The atmosphere is filled with dust, water vapor, and smoke. Especially in production environments, smoke, halogen, toxic gases emitted by equipment, and fine particles can all cause varying degrees of corrosion to valves.
Operators should regularly clean, purge, and refuel valves as specified in the operating procedures. These are effective measures to control environmental corrosion. Installing protective covers on valve stems, installing ground wells on ground valves, and spraying paint on valve surfaces are all ways to prevent corrosive substances from corroding valves.
Increasing ambient temperatures and air pollution, especially for equipment and valves in closed environments, can accelerate corrosion. Open workshops or ventilation and cooling measures should be used whenever possible to mitigate environmental corrosion.
9. Improving Processing Technology and Valve Structure
Corrosion protection for valves is a consideration from the very beginning of design. A valve with a reasonable structural design and correct processing methods will undoubtedly be effective in mitigating corrosion. Therefore, design and manufacturing departments should improve components with unreasonable structural design, incorrect processing methods, and high corrosion risk to ensure they meet the requirements of various operating conditions.
