The valve is a pipeline accessory used to open and close the pipeline, control the flow direction, adjust and control the parameters (temperature, pressure and flow) of the transmission medium. From simple stop valves to various valves used in complex automatic control systems, they have a wide variety and specifications. The nominal diameter of valves ranges from small instrument valves to industrial pipeline valves with a diameter of 10m. The working pressure of the valve can range from 0.0013mpa to 1000MPa, and the working temperature can range from c-270 ℃ to 1430 ℃. During the use of the valve, the sealing surface of the valve is often damaged, and internal leakage will occur if it is damaged. Why does this happen? There are many aspects to understand here. Let's take a look.

機械損傷，密封面在開閉過咱中會產生擦傷、碰傷、擠傷等損壞。兩密封面之間在高溫高壓的作用下發(fā)生原子相互滲透滲出，產生粘連現(xiàn)象。當兩密封面相互移動時，粘連處輕易拉撕。密封面表面粗拙度越高，這種現(xiàn)象越輕易發(fā)生。閥門在封閉過程中、閥瓣在回座過程中會碰傷和擠傷密封面，使密封表面局部磨損或產生壓痕。

Mechanical damage: the sealing surface will be scratched, bumped and squeezed during opening and closing. Under the action of high temperature and high pressure, atoms permeate and exude each other, resulting in adhesion. When the two sealing surfaces move with each other, the adhesive part can be easily pulled and torn. The higher the coarseness of the sealing surface, the easier this phenomenon occurs. During the sealing process of the valve and the reseating process of the valve disc, the sealing surface will be bumped and squeezed, resulting in local wear or indentation on the sealing surface.

介質的沖蝕，它是介質活動時對密封面磨損、沖洗、汽蝕的結果。介質在一定的速度下，介質中的浮游細粒抵觸觸犯密封面，使其造成局部損壞，高速活動的介質直接沖洗密封面，使其造成局部損壞，介質混流和局部汽化時，產氣憤泡爆 破沖擊密封面表面，造成局部損壞。介質的沖蝕加之化學侵蝕交替作用，會強烈的浸蝕密封面。

Medium erosion is the result of wear, flushing and cavitation of the sealing surface when the medium is active. When the medium is at a certain speed, the floating fine particles in the medium collide with the sealing surface and cause local damage. The high-speed moving medium directly washes the sealing surface to cause local damage. When the medium is mixed and partially vaporized, gas bubble blasting will impact the sealing surface and cause local damage. The alternating action of medium erosion and chemical erosion will strongly etch the sealing surface.

介質的化學侵蝕，密封面附近的介質在不產生電流的情況下，介質直接與密封面起化學作用，侵蝕密封面。安裝不正和維修不力導致密封面工作不正常，閥門帶病運轉，過早地損壞了密封面。

Chemical erosion of the medium. When the medium near the sealing surface does not generate current, the medium directly acts with the sealing surface to erode the sealing surface. Improper installation and maintenance led to abnormal operation of the sealing surface, faulty operation of the valve and premature damage to the sealing surface.

選型不當和操縱不好所引起的損壞。主要表現(xiàn)在沒有按工況前提選用閥門，把截斷閥當節(jié)流閥使用，導致封閉比壓過大以及封閉過快或封閉不嚴，使密封面受到?jīng)_蝕和磨損

Damage caused by improper model selection and poor operation. The main performance is that the valve is not selected according to the working conditions, and the block valve is used as a throttle valve, resulting in excessive sealing specific pressure, too fast sealing or lax sealing, so that the sealing surface is eroded and worn