with small diameters are usually connected by external threads or cutting sleeves. Globe valves
with large diameters can also adopt flanged connections.
Most of the globe valves are driven by handwheels or handles. A few high-pressure globe valves
with large diameters or occasions which require automatic operation can also be electrically driven.
The flow resistance of the globe valve
is great, and the closing torque is also great, which affect globe valve being used in places that requires large diameters. At present, the structure of the globe valve has been studied and improved at home and abroad to reduce the flow resistance and closing torque, so that globe valves
can be widely used. For example, internal pressure self-balancing globe valves have emerged in recent years. The applications of various types of globe valves
are briefly described as the following.
Needle globe valves
The needle globe valve is used for precise flow control. The valve clack is usually an integral part of the valve stem and has a very precise needle-like head that fits the valve seat. Moreover, screw pitches of stem threads of needle-shaped globe valves are smaller than those of normal globe valves. Under normal circumstances, the size of the valve seat hole of the needle globe valve is smaller than that of the pipe. Therefore, the needle globe valve is only used in pipelines with a small nominal size.
Oblique globe valves
The valve stem and the passage of the oblique globe valve are at an angle, and the sealing surface of the valve seat and inlet and outlet passages also have a certain angle. The valve body can be made into the integral part or separated part. Oblique globe valves hardly change the flow direction of the fluid, and the flow resistance is the smallest in the globe valve. Hard alloys can be welded on the valve seat and valve sealing surface so as to make the entire valve more resistant to erosion and corrosion, which makes the oblique globe valve very suitable for pipe control in alumina systems and pipes with coke and solid particles.
Angle globe valves
The biggest advantage of the angled globe valve is that it can be installed at the corner of the piping system, which not only don't need a 90°elbow, but also easy to operate. The angled globe valve is very suitable for synthetic ammonia production systems and refrigeration systems in fertilizer plants. For example, J44H-160 and J44H-320 angled globe valves are designed for ammonia production systems.
Steel ball or ceramic ball sealing globe valves
The structural characteristics of the valve are that the valve body is divided into a joint type and a split type, and that the valve clack is a ceramic ball which is made of STL hard alloy steel balls or amorphous powder materials through press forming, high-temperature sintering and fine-prepared processes. Sealing globe valves are usually used for pipes with smaller nominal sizes from DN6 to DN25 due to the size of the sphere. They are applied to high temperature and high pressure steam pipelines of nuclear power plants and thermal power plants, instrumentation pipelines for sampling and sewage systems, and pipelines which are resistant to temperature, pressure, abrasion and corrosion in the chemical engineering system.