Views: 18 Author: Site Editor Publish Time: 2023-03-02 Origin: Site
A globe valve is a valve in which the closing part (disc) moves along the centerline of the seat. According to this moving form of the disc, the change in the valve seat opening is proportional to the disc stroke. Because the stem opening or closing stroke of this type of valve is short, and it has a very reliable shut-off function, and because the change of the valve seat opening is proportional to the stroke of the valve disc, it is very suitable for the adjustment of the flow. Therefore, this type of valve is ideal for use as a shut-off or regulation and throttling.
Once the disc of the globe valve is removed from the closed position, there is no longer contact between its valve seat and the sealing surface of the disc, so the mechanical wear of its sealing surface is very small, so its sealing performance is very good. The disadvantage is that particles in the flowing medium may be trapped between the sealing surfaces. However, if the valve disc is made into a steel ball or porcelain ball, this problem will be solved. Since the seat and disc of most globe valves are relatively easy to repair or replace, and there is no need to disassemble the entire valve from the pipeline when repairing and replacing the sealing element, this is very suitable when the valve and pipeline are welded together.
Due to the change in the direction of the flow of the medium through such valves, the minimum flow resistance of globe valves is also higher than most other types of valves. However, depending on the body structure and the layout of the stem relative to the inlet and outlet channels, this situation can be improved. At the same time, due to the small stroke between the opening and closing of the shut-off valve disc and the sealing surface can withstand multiple opening and closing, it is very suitable for occasions that require frequent opening and closing.
Globe valves can be used in most media process systems. It has developed various forms of globe valves to meet various uses in petrochemical, electric power, metallurgy, urban construction, chemical industry and other sectors.
The use of globe valves is extremely common, but due to the large opening and closing torque, long structural length, and usually the nominal size is limited to DN250 or less, there are also DN400, but special attention should be paid to the inlet and outlet direction when selecting. Generally, most of the globe valve media below DN150 flow from under the disc, while the globe valve above DN200 mostly flows from the top of the disc. This is due to the closing torque of the valve. In order to reduce the opening or closing torque, generally DN200 and above the globe valve is equipped with internal bypass or external bypass valve. However, the American Petroleum Institute standard API 623 stipulates that the maximum nominal pressure is CL2500, the maximum nominal size is NPS12, and its nominal pressure is CL150 ~ CL1500, and the nominal size is NPS24.
The most obvious advantages of globe valves are:
1. During the opening and closing process, the friction between the valve disc and the sealing surface of the valve body is smaller than that of the gate valve, so it is wear-resistant.
2. The opening height is generally only 1/4 of the diameter of the valve seat channel, so it is much smaller than the gate valve.
3. Usually there is only one sealing surface on the valve body and disc, so the production process is better and easy to maintain.
However, the disadvantages of the globe valve cannot be ignored. The disadvantage is mainly that the flow resistance coefficient is relatively large, so it causes pressure loss, especially in hydraulic devices, this pressure loss is particularly obvious.
More details of globe valves, please go to https://www.mingpinmetals.com/Globe-Valve-pl3917724.html