大口径截止阀一般应用在锅炉出口、主分汽缸、蒸汽主管等位置，这些位置存在以下问题:

Large diameter globe valves are generally used in boiler outlets, main distribution cylinders, steam main pipes, and other positions, which have the following problems:

1)锅炉出口一般压差比较大，因此蒸汽流速也更大，对密封面的冲蚀破坏作用也较大。另外锅炉燃烧效率不可能为100%，这样将造成锅炉出口处的蒸汽含水量较大，容易对阀门密封面产生空化和汽蚀的破坏作用。

1) The pressure difference at the outlet of the boiler is generally large, so the steam flow rate is also higher, which has a greater impact on the erosion and damage of the sealing surface. In addition, the combustion efficiency of the boiler cannot be 100%, which will cause a high water content in the steam at the outlet of the boiler, making it easy to cause cavitation and cavitation damage to the valve sealing surface.

2)对锅炉出口及分汽缸附近的截止阀，因为刚从锅炉出来的蒸汽，有间断性过热现象发生，在其饱和的过程中，若锅炉水软化处理不是太好的话，往往会析出部分酸碱物质，对密封面会造成腐蚀和冲蚀;还有一些可结晶的物质也可能附着在阀门密封面结晶，导致阀门无法严密密封。

2) For the shut-off valves near the boiler outlet and distribution cylinder, intermittent overheating occurs due to the steam just coming out of the boiler. During its saturation process, if the boiler water is not softened properly, some acidic and alkaline substances will often precipitate, causing corrosion and erosion to the sealing surface; Some crystalline substances may also adhere to the valve sealing surface and crystallize, causing the valve to fail to seal tightly.

3)分汽缸进出口阀门，因阀后蒸汽用量因生产要求等原因而造成用汽量时大时小，在流速变化较大的情况下，很容易产生闪蒸、空化等现象，从而对阀门密封面造成冲蚀、汽蚀等破坏作用。

3) The inlet and outlet valves of the split cylinder are prone to phenomena such as flash evaporation and cavitation due to varying steam consumption due to production requirements and other factors. When the flow rate changes significantly, this can cause damage to the valve sealing surface, such as erosion and cavitation.

4)一般大管径管线开启时，都需要对管线进行预热，而预热过程一般要求很小流量蒸汽通过，使管线缓慢均匀加热到一定程度后，才能完全开启截止阀，避免造成管线急速升温而产生过度膨胀，损坏部分连接部位。但在这过程中，阀门开度往往非常小，从而造成冲蚀率远远大于正常使用效果，严重降低阀门密封面的使用寿命。

4) When a large diameter pipeline is opened, it is generally necessary to preheat the pipeline, and the preheating process generally requires a small flow of steam to pass through, so that the pipeline can be slowly and evenly heated to a certain degree before the shut-off valve can be fully opened to avoid excessive expansion caused by rapid heating of the pipeline, which may damage some connection parts. However, during this process, the valve opening is often very small, resulting in a much higher erosion rate than normal use, seriously reducing the service life of the valve sealing surface.

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