Corrosion is one of the important elements that cause valve damage. In valve protection, valve corrosion prevention is an important issue to consider. Why is the valve corroded after all? How should the valve stop corrosion prevention? What is the basis for the selection of corrosion-resistant valves? Come and have a look!

閥門(mén)腐蝕方式

Valve corrosion mode

金屬的腐蝕主要是化學(xué)腐蝕和電化學(xué)腐蝕惹起的，非金屬資料的腐蝕普通是直接的化學(xué)和物理作用惹起的毀壞。

The corrosion of metals is mainly caused by chemical corrosion and electrochemical corrosion. The corrosion of non-metallic materials is generally caused by direct chemical and physical effects.

1.化學(xué)腐蝕

1. Chemical corrosion

四周介質(zhì)在不產(chǎn)生電流條件下，直接與金屬起化學(xué)作用，而使其毀壞，如高溫枯燥氣體和非電解溶液對(duì)金屬的腐蝕。

Under the condition that no current is generated, the surrounding medium directly reacts with the metal and destroys it, such as the corrosion of metal by high-temperature dry gas and non electrolytic solution.

2.電化學(xué)腐蝕

2. Electrochemical corrosion

金屬與電解質(zhì)相接觸，產(chǎn)生電子活動(dòng)，而使本身在電化學(xué)作用遭受毀壞，這是腐蝕的主要方式。

The main way of corrosion is that the metal contacts with the electrolyte and produces electronic activities, which destroys itself in the electrochemical action.

常見(jiàn)的酸堿鹽溶液腐蝕、大氣腐蝕、土壤腐蝕、海水腐蝕、微生物腐蝕、不銹鋼的點(diǎn)腐蝕和縫隙腐蝕等等，都是電化學(xué)腐蝕。

The common acid-base salt solution corrosion, atmospheric corrosion, soil corrosion, seawater corrosion, microbial corrosion, spot corrosion and crevice corrosion of stainless steel are all electrochemical corrosion.

電化學(xué)腐蝕不只發(fā)作于能夠起化學(xué)作用的兩種物質(zhì)之間，而且還由于溶液的濃度差、四周氧氣的濃度差、物質(zhì)構(gòu)造的微小差異等等緣由，產(chǎn)生電位的差別，而取得腐蝕的動(dòng)力，使電位低、處于陽(yáng)板位置的金屬受損失。

Electrochemical corrosion occurs not only between two substances that can play a chemical role, but also due to the concentration difference of the solution, the concentration difference of oxygen around, the slight difference of material structure and other reasons, resulting in the difference of potential, and obtaining the power of corrosion, so that the metal with low potential and in the anode position is lost.

9大防腐措施

9 major anti-corrosion measures

1.依據(jù)腐蝕介質(zhì)選用耐蝕資料

1. Select corrosion resistance data according to corrosion medium

在消費(fèi)實(shí)踐中，介質(zhì)的腐蝕是十分的復(fù)雜的，即便在用一介質(zhì)中運(yùn)用的閥門(mén)資料一樣，介質(zhì)的濃度、溫度、壓力不同，介質(zhì)對(duì)資料腐蝕也不一樣。介質(zhì)溫度每升高10℃，腐蝕速度約增加1~3倍。

In consumption practice, the corrosion of medium is very complex. Even if the valve data used in a medium is the same, the corrosion of medium to data is different with the concentration, temperature and pressure of medium. The corrosion rate increases by about 1-3 times when the medium temperature increases by 10 ℃.

介質(zhì)濃度對(duì)閥門(mén)資料腐蝕影響很大，如鉛處在濃度小的硫酸中，腐蝕很小，當(dāng)濃度超越96%時(shí)，腐蝕急劇上升。而碳鋼相反，在硫酸濃度為50%左右時(shí)腐蝕更嚴(yán)重，當(dāng)濃度增加到6%以上時(shí)，腐蝕反而急劇降落。

The medium concentration has a great impact on the corrosion of valve data. For example, the corrosion of lead in sulfuric acid with small concentration is very small. When the concentration exceeds 96%, the corrosion rises sharply. On the contrary, the corrosion of carbon steel is the most serious when the concentration of sulfuric acid is about 50%. When the concentration increases to more than 6%, the corrosion decreases sharply.

有如鋁在濃度80%以上的濃硝酸中腐蝕性很強(qiáng)，但在中、低濃度的硝酸中腐蝕反而嚴(yán)重。不銹鋼雖說(shuō)對(duì)稀硝酸耐蝕性很強(qiáng)，但在95%以上的濃硝酸中腐蝕反而加重。

For example, aluminum is highly corrosive in concentrated nitric acid with a concentration of more than 80%, but it is severely corroded in medium and low concentrations of nitric acid. Although stainless steel has strong corrosion resistance to dilute nitric acid, the corrosion is aggravated in more than 95% concentrated nitric acid.

從以上幾例能夠看出，正確選用閥門(mén)資料應(yīng)依據(jù)詳細(xì)狀況，剖析各種影響腐蝕要素，按有關(guān)防腐手冊(cè)選用資料。

From the above examples, it can be seen that the correct selection of valve data should be based on the detailed situation, analyze various factors affecting corrosion, and select data according to the relevant anti-corrosion manual.

2.采用非金屬資料

2. Use non-metallic materials

非金屬耐腐蝕性優(yōu)秀，只需閥門(mén)運(yùn)用溫度和壓力契合非金屬資料的請(qǐng)求，不但能處理腐蝕問(wèn)題，而且可儉省貴重金屬。

Non metallic corrosion resistance is excellent. As long as the application temperature and pressure of the valve meet the requirements of non-metallic data, it can not only deal with corrosion problems, but also save precious metals.

閥門(mén)的閥體、閥蓋、襯里、密封面等常用非金屬資料制造，至于墊片，填料主要死非金屬資料制造的。

The valve body, bonnet, lining, sealing surface and other commonly used non-metallic materials are manufactured. As for gaskets, fillers are mainly manufactured from non-metallic materials.

用聚四氟乙稀、氯化聚醚等塑料、以及用自然橡膠、氯丁橡膠、丁晴橡膠等橡膠做閥門(mén)襯里，而閥體、閥蓋主體是普通鑄鐵、碳鋼制成。即保證了閥門(mén)強(qiáng)度，又保證了閥門(mén)不受腐蝕。

The valve is lined with polytetrafluoroethylene, chlorinated polyether and other plastics, as well as natural rubber, neoprene, nitrile rubber and other rubbers, while the body and bonnet are made of ordinary cast iron and carbon steel. It not only ensures the strength of the valve, but also ensures that the valve is not corroded.

夾管閥也是依據(jù)橡膠的優(yōu)秀耐腐蝕性能和優(yōu)良變性能而設(shè)計(jì)出來(lái)的。如今越來(lái)越對(duì)的用尼龍、聚四氟乙稀等塑料，用自然橡膠和合成橡膠做各種各樣的密封面，密封圈，用于各類閥門(mén)上。

The pinch valve is also designed based on the excellent corrosion resistance and excellent denaturation of rubber. Nowadays, nylon, polytetrafluoroethylene and other plastics, natural rubber and synthetic rubber are increasingly used to make various sealing surfaces and rings for all kinds of valves.

這些用作密封面的非金屬資料，不但耐腐蝕性好，而且密封性能好，特別適于帶顆粒介質(zhì)中運(yùn)用。當(dāng)然，它們的強(qiáng)度和耐熱性都較低，應(yīng)用的范圍遭到限制。

These non-metallic materials used as sealing surfaces have not only good corrosion resistance, but also good sealing performance, and are especially suitable for use in media with particles. Of course, their strength and heat resistance are low, and the scope of application is limited.

柔性石墨的呈現(xiàn)，使非金屬進(jìn)入了高溫范疇，處理了長(zhǎng)期難以處理的填料和墊片泄露問(wèn)題，而且是很好的高溫光滑劑。

The appearance of flexible graphite makes non-metallic materials enter the high-temperature category, which solves the problem of packing and gasket leakage that is difficult to deal with for a long time, and is a good high-temperature smoothing agent.

常用非金屬資料適用工況：

Applicable working conditions of common non-metallic materials:

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