Humidity and Corrosion Effects
The humidity in marine environments is usually high, which has a significant impact on valves. In general, the humidity of the valve should be maintained between 50% and 80% relative humidity, while the humidity in marine environments often exceeds this range. Valves made of different materials are at risk of corrosion in high humidity marine environments. For example, cast iron valves are prone to rust, and they are more prone to corrosion when the humidity is too high; Although stainless steel valves have strong corrosion resistance, they can also cause internal corrosion in high humidity marine environments. In addition, factors such as ocean salt vapor can accelerate the corrosion process of valves, affecting their normal use and lifespan.
The impact of chemical substances
Chemicals in the marine environment can have an impact on valve materials. There are various salts dissolved in seawater, which mainly come from the weathering products of crustal rocks and soluble compounds ejected from seamounts. More than 80 elements have been determined. These chemicals may cause chemical reactions when in contact with valve materials, leading to a decrease in valve material performance. For example, in special marine related environments such as offshore drilling platforms and chemical plants, the impact of chemicals on valve materials is more pronounced, making valves in these environments more demanding in terms of humidity and other factors.
The comprehensive impact of work pressure and humidity
In marine environments, some valves are under high pressure. High pressure valves often have stricter humidity requirements because in high-pressure environments, humidity can accelerate corrosion inside the valve, which may lead to serious safety accidents. The combined effect of high pressure and high humidity in the marine environment increases the risk of valve failure, placing higher demands on the safety and reliability of valves.
Corrosion and wear effects
Seawater is a typical corrosive medium in nature, and the corrosion and wear of seawater valves in marine engineering are very complex, including turbulent corrosion, erosion corrosion, and sliding corrosion and wear. Among them, turbulent corrosion and erosion corrosion have been studied extensively, with clear mechanisms and established theoretical models. Sliding corrosion wear is also a typical loss mode of fully immersed zone valves. Studying the corrosion wear of metal materials in the fully immersed zone on the corrosion wear mechanism of valves in seawater and the development of corrosion-resistant wear materials are of great significance. For example, the corrosion and wear behavior of 304 stainless steel valves in seawater is influenced by various factors, such as seawater pH, halide ion concentration, initial surface roughness, and anode applied potential. In high pH environments, seawater exhibits good lubricity and low corrosiveness, and 304 stainless steel valves show low corrosion and wear rates; The high concentration of halide ions improves the lubricity of seawater and reduces the wear rate, but at the same time increases the corrosion of metals by seawater, especially increasing the sensitivity of 304 stainless steel valves to pitting corrosion; The larger the initial surface roughness of the valve, the longer the running in time, and the more severe the abrasive wear; Applying an external potential to the anode will accelerate the corrosion of 304 stainless steel valves, alter the contact surface characteristics, and increase their corrosion and wear rate.
