Views: 0 Author: Site Editor Publish Time: 2021-05-07 Origin: Site
The correct operation of stainless steel flange equipment is very important, and stainless steel flanges, nickel alloys, and titanium alloys form a very durable pure protective film with strong adhesion, so they have a good corrosion resistance to erosion and corrosion. The demand flow mechanism to avoid erosion. Corrosion measures and protective structure design and material selection can reduce or avoid erosion and corrosion. Equipment, installations and pipelines can be designed as the velocity of the media impinging flow in the metal business and the geometric streamline shape of the lake flow.
The structural design that adopts the radius of the corner diameter to gradually change the direction of the fluid will reduce the erosion and corrosion. Appropriate adjustment of medium such as value, use of corrosive agent for dissolved oxygen, and passivation treatment can all reduce the degree of corrosion. It is sometimes very economical and suitable to design and use easy-to-replace and thickened parts in places with severe erosion and corrosion. When the design and the state of the medium cannot be changed, the selection of materials with better corrosion resistance will also enhance the stable surface of the metal surface relative to the medium to avoid erosion corrosion. Cavitation corrosion. Cavitation corrosion is a special form of erosion corrosion. The pressure drop of the high-velocity corrosive fluid is enough to form bubbles, and then burst on the material surface. This kind of burst produces end-pressure shock, which not only tears the metal layer, but even breaks the metal body into tiny particles from the matrix. Therefore, this kind of infringement forms rough pits and final perforations on the material surface. Cavitation corrosion is not uncommon in the assembly of turbine blades, ship propeller propellers, and pressure-varying pipe passages.
When the fluid passes through a curved surface, the pressure will decrease, such as an airfoil. When the pressure of the medium drops below the vapor pressure of the medium at a certain point, bubbles will form locally to form a boiling state. These bubbles land on the metal surface and burst and form a continuous flow. The pressure shock is enough to swallow and hollow out the metal surface, protect the mold from the brittle corrosion products attached to the metal surface, and the bubble burst can completely crush the protective layer. Just like flushing corrosion, the thinning or detachment of the metal surface protective film causes fresh metal to be exposed and undergoes more serious corrosion.
The progress of Ziliu makes the corrosion worse. However, even without considering these factors, the constant pressure shock wave itself is enough to hollow out the metal surface. Pump turbines, ship propellers, engines and generator turbine rotors all directly contact high-speed fluids. Cast iron, cast steel and stainless steel flanges are commonly used materials, and severe cavitation corrosion has been reported. For tough metal materials, simple cavitation has no corrosive impact. In fact, the metal is continuously processed to be hard, fatigued, brittle and produce micro-cracks. Therefore, cemented carbide is more resistant to simple cavitation impact. The role of measures and protections to avoid cavitation corrosion is to adopt negative protection. The purpose is not to reduce the corrosion rate of materials, but to isolate and buffer the landing, burst and impact of cavitation bubbles on the metal surface through the precipitated hydrogen gas, which can reduce cavitation corrosion.
The air in the corrosive medium can also corrode by cavitation, because the trapped air can easily become the nucleus of the cavity under lower pressure. Although the use of corrosion-resistant materials cannot be exempted, it can reduce the degree of cavitation corrosion. It is possible to remove the pressure drop bubble generation from the design on the metal surface in contact with the high-speed medium fluid. The correct operation of stainless steel flange equipment is also very important. For example, the pump should not be used in the medium of obstruction or turbulent flow. Vibration corrosion is another special form of erosion corrosion. The metal substrate is in contact with the load on it. In addition, the repeated micro-motion caused by vibration between the solids causes the wear and corrosion of the metal matrix. This tiny movement not only wears off the oxygen film on the metal substrate surface, but also makes the exposed fresh metal surface more oxygen, and overlaps with the worn-off oxygen debris as additional abrasive friction, forming double abrasion, so it is The behavior and causes of wear, abrasion, and corrosion that are aggravated by corrosion. Erosion corrosion is the corrosion of fluid liquid. In contrast, grinding corrosion is the wear caused by the mutual movement of the alloy and another solid in dry and humid air. The oxygen film formed on the alloy surface in the dry air is worn away due to contact vibration and becomes a new abrasive.