Large-diameter globe valves are generally used in boiler outlets, main gas-distributing cylinders, main steam pipes and so forth.
Generally, the pressure difference at the boiler outlet is large, so the steam velocity is high and the erosion destruction to the sealing surface is great. In addition, the combustion efficiency of the boiler cannot be 100%, otherwise the steam at the outlet of the boiler will have a large water content, easily causing cavitation to the valve sealing surface.
For the stop valve near the boiler outlet and the gas-distributing cylinder, the steam just discharged from the boiler has intermittent overheating. In the process of saturation of the steam, if the boiler water treatment is not carried out well, some acid and base will be often separated out, which will cause corrosion and erosion to the sealing surface. There are also some crystallizable substances that may adhere to the sealing surface of the valve and crystallize, resulting in the valve not being tightly sealed.
For the inlet and outlet valves used for the gas-distributing cylinder, the steam consumption varies from time to time due to the steam consumption of the outlet of the valve, production requirements and other reasons. When the flow rate changes greatly, it is easy to produce flash evaporation, cavitation and so on, thus causing erosion, cavitation and other destructive effects on the valve sealing surface.
Usually, when a large-diameter pipeline is operated, the pipeline needs to be preheated, and the preheating process generally requires a small flow of steam to pass through the pipe, so that the globe valve can be completely opened after the pipeline is slowly and uniformly heated to a certain extent, which avoids excessive expansion caused by rapid temperature rise of the pipeline and damage to some joints. However, in this process, the valve opening is often very small. As a result, the erosion rate is much higher than normal, seriously reducing the service life of the valve sealing surface.
Generally, the pressure difference at the boiler outlet is large, so the steam velocity is high and the erosion destruction to the sealing surface is great. In addition, the combustion efficiency of the boiler cannot be 100%, otherwise the steam at the outlet of the boiler will have a large water content, easily causing cavitation to the valve sealing surface.
For the stop valve near the boiler outlet and the gas-distributing cylinder, the steam just discharged from the boiler has intermittent overheating. In the process of saturation of the steam, if the boiler water treatment is not carried out well, some acid and base will be often separated out, which will cause corrosion and erosion to the sealing surface. There are also some crystallizable substances that may adhere to the sealing surface of the valve and crystallize, resulting in the valve not being tightly sealed.
For the inlet and outlet valves used for the gas-distributing cylinder, the steam consumption varies from time to time due to the steam consumption of the outlet of the valve, production requirements and other reasons. When the flow rate changes greatly, it is easy to produce flash evaporation, cavitation and so on, thus causing erosion, cavitation and other destructive effects on the valve sealing surface.
Usually, when a large-diameter pipeline is operated, the pipeline needs to be preheated, and the preheating process generally requires a small flow of steam to pass through the pipe, so that the globe valve can be completely opened after the pipeline is slowly and uniformly heated to a certain extent, which avoids excessive expansion caused by rapid temperature rise of the pipeline and damage to some joints. However, in this process, the valve opening is often very small. As a result, the erosion rate is much higher than normal, seriously reducing the service life of the valve sealing surface.
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