Introduce the cause of internal leakage of large caliber globe valve

1) Boiler outlet pressure difference is generally larger, so the steam flow rate is larger, and the erosion damage to the sealing surface is also greater. In addition, the combustion efficiency of the boiler can not be 100%, which will result in a larger water content in the steam at the outlet of the boiler, and easy to cause cavitation and cavitation damage to the valve sealing surface.
2) For the cut-off valve near the outlet of the boiler and the sub-cylinder, because the steam just coming out of the boiler has intermittent overheating, in the process of its saturation, if the softening treatment of the boiler water is not too good, it will often precipitate some acid-base substances, which will cause corrosion and erosion to the sealing surface; and some crystallizable substances will also be found. It may also adhere to the valve sealing surface to crystallize, resulting in the valve can not be tightly sealed.
3) For the inlet and outlet valves of distributor cylinders, the steam consumption after the valves is large or small due to the production requirements and other reasons. When the flow rate changes greatly, it is easy to produce flashing, cavitation and other phenomena, which will cause erosion and cavitation on the sealing surface of the valves.

4) Generally, when large diameter pipeline is opened, it is necessary to preheat the pipeline, and the preheating process generally requires a small flow of steam to pass through, so that the pipeline is heated slowly and evenly to a certain extent, before the cut-off valve can be fully opened, so as to avoid excessive expansion caused by rapid heating of the pipeline and damage parts of the connection. But in this process, the valve opening is often very small, resulting in erosion rate far greater than the normal use effect, seriously reducing the service life of the valve sealing surface.