API Globe Valve Flange Type Casting Steel

The working principle of API Globe Valve and national standard globe valve is similar, but the structure will be different. Similarly, the use of raw materials is also different. It should be said that the American standard globe valve is more widely used in international projects and is a general and excellent international standard.

When Globe valve is closed, pressure must be applied to the valve disc to force the sealing surface not to leak. When the medium enters valve six from below the valve disc, the resistance that the operating force needs to overcome is the friction force between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve, so the valve The diameter of the stem should be large, otherwise the failure of the top of the valve stem will occur. In recent years, since the emergence of self-sealing valves, the medium flow direction of the flanged globe valve has been changed from the top of the valve disc into the valve cavity. At this time, under the action of the medium pressure, the force to close the valve is small, while the force to open the valve is large. The diameter of the rod can be reduced accordingly. At the same time, under the action of the medium, this form of valve is also tighter. my country's valve "Three Chemicals" once stipulated that the flow direction of the globe valve should be from top to bottom.

When the globe valve is opened, when the opening height of the valve disc is 25% to 30% of the nominal diameter, the flow rate has reached the maximum, indicating that the valve has reached the fully open position. Therefore, the fully open position of the globe valve should be determined by the stroke of the valve disc. This type of valve should generally be installed horizontally in the pipeline

The American standard globe valve can only flow the medium in one direction, and it is directional during installation. The structural length of the American standard globe valve is longer than that of the Gate Valve, and at the same time, the fluid resistance is large, and the sealing reliability is not very strong during long-term operation.

The advantage of the American standard globe valve is that in the process of opening and closing, the friction between the disc and the sealing surface of the valve body is smaller than that of the gate valve, so it is very wear-resistant. At the opening height, it is generally 1/4 of the diameter of the valve seat passage, so it is much smaller than the gate valve. Usually there is only one sealing surface on the valve body and the valve disc. In the manufacturing process, the performance is better and the maintenance is very convenient.

The working principle of American standard globe valve, use and maintenance

1. Globe valves should be selected on the pipelines and devices of high temperature and high pressure media. Such as nuclear power plants, petrochemicals, thermal power plants, high temperature and high pressure pipelines of industrial systems.

2. On the pipeline where the convection resistance is required. That is, where the pressure loss is not considered.

3. Instrument valves, sampling valves, needle valves, pressure gauge valves, etc. can be selected for small valves.

4. Flow adjustment and pressure adjustment, but the requirements for adjustment accuracy are not very high, and the diameter of the pipeline is relatively small, for example, it should be selected on pipelines with a nominal diameter of ≤50mm.

5. Small fertilizers and large fertilizers in synthetic industrial production should choose high pressure angle globe valve or high pressure angle globe valve with nominal pressure PN160 nominal pressure 16MPa or PN320 nominal pressure 32MPa.

6. In the desiliconization workshop and the pipelines prone to coking in the alumina Bayer process, it is easy to choose the direct-flow stop valve and the direct-flow stop valve with the valve body separated, the valve seat can be removed, and the cemented carbide sealing pair.