Bonnet Globe Valve

What is bonnet globe valve?

The bonnet of the globe valve has many connection methods, usually welding, thread, flange, or by means of a pressure self-sealing device, or the bonnet and the valve body can be made into a whole without connection. So the bonnet globe valve refers not just to a certain kind of valve, but to the generality of a type of valve.

Welded bonnet globe valve

The structure of welded connection bonnet is not only economical but also reliable, and is not limited by valve size, operating pressure and temperature. But its disadvantage is that it is difficult to maintain, and the inside of the valve can only be accessed if the welding seam is removed. Therefore, welded bonnets are usually only used for long-term maintenance-free valves, disposable valves, or valves where it is more difficult to seal the bonnet connection than disassemble the valve for overhaul.

The difference between welded bonnet globe valve and welded globe valve:

Welded bonnet globe valves are different from welded globe valves. Welded globe valve refers to the connection method of the valve. Welded bonnet globe valve refers to the design form of globe valve bonnet. In the valve of this design, the valve body and the bonnet are connected by threaded connection, and they are all welded and sealed. If special requirements, penetration welding can also be used. Welded globe valve is suitable for small-diameter pipes, and the sealing surface is not easy to wear and scratch. It has the advantages of good sealing performance, small valve disc stroke when opening and closing, and short opening and closing time.

Bolted bonnet globe valve

The structure of the threaded connection valve cover is relatively simple and the price is low. However, the gasket of the bonnet fits tightly against the rotating surface, and loosening or tightening the bonnet is likely to destroy the joint surface. If the valve size is large, the torque required to tighten the bonnet is large. Therefore, the use of threaded bonnet outwards is limited to valves with a nominal size not greater than DN80.

The bonnet can also be connected to the valve body by a separate threaded ring sleeve. The advantage of this configuration is that the joints are fastened so that the joint surfaces do not move relative to each other. Therefore, even if the valve cover is frequently tightened, the joint surface is not easily damaged. Like the threaded bonnet, the bonnet connected with a threaded ring sleeve is limited to valves with a nominal size not greater than DN80.

Flanged bonnet globe valve

The advantage of flanged bonnet over threaded bonnet is that its tightening force can be distributed to all bolts. Therefore, flanged bonnets are suitable for valves of any size and pressure class. However, with the increase of valve size and pressure, the volume and weight of the valve of this structure will become larger and larger. When the valve operating temperature is higher than 350°C (600°F), the load-carrying capacity of the bolt is greatly reduced due to creep relaxation. The flange connection can also be sealed by welding in applications with demanding requirements.

Pressure Sealed Bonnet Globe Valve

This structure compresses the joint surface by medium pressure, which overcomes the disadvantage of heavy weight of other structures. And as the medium pressure increases, the valve cover seal will become tighter and tighter. This structure has become the preferred bonnet connection method for large valves with high temperature and high pressure.

In order to ensure that the pressure self-sealing bonnet can maintain the sealing performance under the condition of large pressure and temperature fluctuations, a disc spring can be loaded on the fastening stud of the bonnet, so that the pressure self-sealing bonnet has a dynamic load function.

The dynamic load bonnet bolts store the required sealing load under constant pressure or temperature transitions. The dynamic load automatically compensates for changes in the fluctuating transition, and as the pressure decreases, the bonnet moves, maintaining a positive load on the pressure sealing gasket.

Connection form without bonnet

Small globe valves can be connected without a bonnet. The inside of the valve is accessible through the stuffing box opening, which should be large enough to pass the valve components.

Different names for globe valve

According to different driving methods: globe control valve with pneumatic actuator, electric globe valve, hydraulic globe valve, etc.;

According to the material: globe valve stainless steel, 304 stainless steel globe valve, 316 stainless steel globe valve, etc.;

According to the diameter: globe valve dn80, globe valve dn40, globe valve dn25, globe valve dn32, etc.

If you need a globe valve, you can contact our sales engineer to help you choose the type. As a 17-year-old valve company, we have the strength to provide you with the most complete series of products. We are mainly engaged in various high temperature and high pressure power station valves. , look forward to your contact.

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