In valve applications, corrosion is the destruction and deterioration of materials under the action of various environments. Because corrosion is one of the important factors leading to valve damage, so Wuhan Xiete Valve Technology Co., Ltd. in the valve manufacturing process, anti-corrosion measures are the primary consideration.

Valve corrosionDivided into the followingForm

Metal valve corrosion has two forms: uniform corrosion and local corrosion. The rate of uniform corrosion can be evaluated by the annual average corrosion rate. Different parts of the valve are made of different grades of materials, and some parts can be made of less corrosive materials.

1. Uniform corrosion

Uniform corrosion is carried out over the entire surface of the metal. Such as stainless steel, aluminum, titanium, etc. in the oxidation of the environment to produce a layer of protective film, the film under the metal state of uniform corrosion. Another phenomenon, the metal surface corrosion exfoliation, this corrosion is the most dangerous.

2. Local corrosion

Local corrosion occurs in the local position of the metal, it has the following forms:

Pitting usually occurs in the passivation film or protective film on the metal, is due to the existence of defects on the metal surface, the solution can destroy the active ions of the passivation film, so that the passivation film local damage, into the metal interior, become the corrosion hole, it is one of the metal destructive and hidden dangers of the largest corrosion form.

Crevice corrosion occurs in welding, riveting, gasket or sediment under the environment, it is a special form of pitting corrosion. The prevention method is to eliminate the gap.

The delamination corrosion occurs in the layered structure. The corrosion first develops vertically inward, and then corrodes the parallel substances on the surface. Under the expansion force of the corrosion, the surface is layered and peeled off.

Stress corrosion occurs when cracking occurs under the simultaneous action of corrosion and tensile stress. The method of preventing stress corrosion; eliminate or reduce the stress generated in welding and cold working through heat treatment, improve the unreasonable valve structure, avoid stress concentration, adopt electrochemical protection and spray anti-corrosion coating. Add corrosion inhibitor, apply compressive stress and other measures.

Corrosion fatigue occurs at the site of the combined action of alternating stress corrosion, causing the metal to crack. Heat treatment can be carried out to eliminate or reduce stress, surface shot peening and electro-galvanized, chromium, nickel, etc., but pay attention to the coating can not have tensile stress and hydrogen diffusion phenomenon.

Selective corrosion occurs in materials with different components and impurities. In a certain environment, some elements are leached by corrosion, and the remaining uncorroded elements are spongy.

Wear and corrosion is a form of corrosion produced by the alternating action of fluid on metal wear and corrosion. It is a common corrosion of valves. This kind of corrosion occurs in the sealing surface. Prevention methods: selection of corrosion-resistant, wear-resistant materials, improved structural design, the use of cathodic protection.

Corrosion is the destruction caused by the diffusion of hydrogen atoms into the interior of the metal in the form of hydrogen bubbling, hydrogen embrittlement and hydrogen erosion.

Strong steels and steels containing non-metals are prone to hydrogen bubbling. Hydrogen bubbling is easy to occur when petroleum contains sulfides and hydrides. Use dead steel without holes instead of boiling steel with holes, use rubber and plastic for protection, and add corrosion inhibitor to prevent bubbling.

The lattice in strong steel is highly denatured, and after hydrogen atoms enter, the 4 lattice strain is greater, causing financial embrittlement. Alloy steel containing nickel and lead should be selected, high strength steel with large hydrogen embrittlement should be avoided, and hydrogen embrittlement should be avoided or reduced in welding, electroplating and pickling. High temperature, high pressure hydrogen into the metal, and a combination of elements will produce chemical reaction and destruction, known as hydrogen corrosion. Austenitic stainless steel is completely resistant to high temperature hydrogen corrosion.

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    Wuhan Xiete Valve Technology Co., Ltd.Focus on all kinds of valves,Filter,Gas drainer,Throttle orifice plateIt is a professional manufacturing enterprise integrating R & D, production, sales and after-sales, with 20 years of rich experience in the industry. It owns the Xiete valve brand, builds the best R & D professional team in the industry, and has a number of independently designed and developed patented products. Provide customers with the bestValve function customization solution, and has successfully provided professional design customization services for many enterprises and institutions. At the same time, Wuhan Xiete Valve Technology Co., Ltd. has obtained ISO9001 quality system certification and TS special equipment license. Our product types, complete styles, quality assurance, factory direct sales, economical, convenient and fast to provide customers with one-stop service!

 

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