The selection and operation of globe valves: Globe valves are valves that close the valve disc moving along the center line of the valve seat. Depending on the type of movement of the valve disc, the change in valve seat opening is in direct proportion to the valve disc stroke. Due to the valve stem of this type of valve opening or closing stroke is relatively short, but also has a very reliable cut-off function, but also because the valve seat opening changes in proportion with the valve stroke is proportional to the flow rate is very suitable for regulation. Therefore, this type of valve is ideally suited for shut-off or regulation as well as throttling. Globe valve selection principle is: 1, high temperature, high pressure medium pipe or device should use the globe valve. Such as thermal power plants, nuclear power plants, petrochemical systems of high temperature and high pressure on the pipeline. 2, on the pipeline on the strict requirements of resistance on the pipeline. That is, the pressure loss is not taken into account. 3, small valve optional needle valve, instrument valve, sampling valve, pressure gauge valve. 4, there is flow regulation or pressure regulation, but the regulation accuracy is not high, and the pipeline diameter is relatively small, such as the nominal pass through the pipeline ≤ 50mm, should be used. 5, synthetic industrial production of small fertilizers and large-scale fertilizer should use nominal pressure PN160 nominal pressure 16MPa or PN320 nominal pressure 32MPa high-pressure angle type stop valve or high-pressure angle throttle. 6, Alumina Bayer process in the production of desiliconization workshop, easy coking pipe, easy to choose the valve body separate, seat can be place, the sealing of the cemented carbide DC globe valve or DC throttle. 7, urban construction in the water supply and heating engineering, the nominal pass through the smaller pipe, the choice of cut-off, balance valve or plunger valve, such as the nominal pass through the pipe less than 150mm. The most obvious advantage is that during the opening and closing process, the valve plate is wearable because of the lower friction between the sealing surfaces of the valve body and the gate valve. The opening height is only 1/4 of the diameter of the valve seat passage, so it is much smaller than the valve. Usually there is only one sealing surface on the valve body and the valve disc, so manufacturing technology is relatively good and easy to maintain. Selection of different materials, can be applied to water, steam, oil, nitric acid, acetic acid, oxidizing media, urea and other media. For stop valves, not only will it be installed and maintained, but it will also be operated. Opening and closing the globe valve, force should be smooth, can not impact. Some of the impact of opening and closing of the high-pressure globe valve components have been considered this impact and the general cut-off valve can not wait for Gang. When the cut-off valve fully open, the hand wheel should be reversed a little, so tight between the threads, so as not to loosen the damage. The first pipe, the internal dirt more, the valve can be micro-Kai, the use of high-speed flow of media, it washed away, and then gently shut down (can not be closed quickly, fierce closed to prevent residual impurities sealing surface) , Open again, so repeated several times, rinse the dirt, then put into normal work. Normally open stop valve, the sealing surface may be stuck with dirt, shut down also use the above method to flush it clean, and then officially closed. Such as the hand wheel, the handle is damaged or lost, should be immediately fitted, can not be replaced by the board wrench in order to avoid damage to the stem square, opening and closing ineffective, resulting in an accident in production. Some media, after the closure of the valve is closed to cool the valve contraction, the operator should be closed again at an appropriate time, so that the sealing surface without fissure, or medium flow through the slit at high speed, it is easy erosion seal surface. Operation, if found to be too strenuous operation, should analyze the reasons. If the packing is too tight, may be appropriate to relax, such as stem skew, should notify the staff to repair. Some shut-off valve, in the closed state, the closure of the thermal expansion, resulting in difficult to open; If you must open at this time, the valve cap can be loosening a half turn to a circle, eliminating the stem stress, and then the plate hand wheel.
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