Author:Site Editor Publish Time: 2019-01-11 Origin:Site
The double offset butterfly valve is gradually improved by the ordinary butterfly valve to adapt to different working conditions. The earliest butterfly valve structure is mainly the center door panel structure, similar to the adjustment butterfly valve, that is, the axis of the valve stem and the butterfly plate coincides with the center of the industrial valve body pipe.
l Components of Butterfly Valves
l What Is Lowest Working Temperature of Butterfly Valves?
l What Is Highest Working Temperature of Butterfly Valves?
l What Should You Pay Attention to?
Double offset butterfly valve seal consists of metal-rubber, which is sealed by a small compression of the rubber on the metal seat to create a seal. In the long-term work, the axial end positions of the valve body and the disc are always rotated in the state of rubber compression. Therefore, there is wear on the rubber seal for long-term use. At the same time, due to the rubber use temperature (≤120 °C) and rubber seat forming and forming restrictions (nominal diameter DN ≤ 1200mm), such butterfly valves cannot be used in the larger piping system of the metallurgical industry.
Since most of the metallurgical system pipelines are high temperature gas medium (≥200 °C), the sealing is a metal hard sealing butterfly valve, that is, a double offset metal hard sealing butterfly valve. The valve seat is 2Cr13 or surfacing hard alloy. The disc is an elastic sealing ring. The surface is in contact with the surface. The elastic sealing ring creates a seal under the action of the electric device to seal the valve. Since the material of the sealing pair is selected as a metal, the double eccentricity can be used at temperatures above 400 °C. However, since the seal is made of all-metal material, it is difficult to achieve the desired Class A (no visible leakage) due to the seal leakage, which is generally Class C. On the other hand, due to the limitation of material elasticity, the elasticity of the metal is easily lost under high temperature conditions. Therefore, after a period of use, the internal leakage of the valve is significantly increased, thereby losing the meaning of the valve seal and causing the use of the valve. Life expectancy is significantly shortened.
The development of multi-level double offset metal hard sealing butterfly valve solves the problem of high temperature material losing elasticity. The sealing material of the multi-layer double offset metal hard sealing butterfly valve is a composite material (metal and non-metal inter layer), which has the advantages of high temperature resistance (≤500 °C), good resistance to aging and high temperature, especially in the middle. The non-metallic inter layer enables the seal of the seal to produce a step seal form. After long-term use, it can maintain good and reliable high temperature use effect, thus extending the service life of the valve. Widely used in various systems of metallurgical blast furnaces.
Since the application conditions of the multi-level double offset metal hard sealing butterfly valve are mostly the normally open or normally closed state at high temperature. In the normally open state of the valve for several months or even one year, there is a long period of medium scouring of the inlet side seal of the medium to the disc. Such scouring is extremely detrimental to non-metallic layers, and once the valve is required to be closed, severe localized leakage will occur at this location. In response to this situation, the position of the multi-layer sealing ring is changed from the position of the original butterfly plate to the position of the sealing portion of the valve body, and the hard alloy is welded at the sealing ring of the butterfly plate to avoid the above problems.
The development of this butterfly valve has been widely applied by various high temperature systems of metallurgical blast furnaces. For more information, you can visit our company website.
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