Each control valve has its own advantage and so does the globe valve. But when you want to choose the right one, you need to know everything about different globe valve parts and their function to make an informed decision and also make sure that this control valve type is the right fit for your system and also avoid different problems and issues that are caused by a failing valve. In this article, Linquip will tell you all about different globe valve parts and also explain their use and application.
What is a globe valve?
Globe valves are types of valves that regulate the flow of different gasses or liquids. They can also start or stop the flow. Globe valves have different parts such as disc, plug, ring seat, etc. and there are also different Globe valve types in the market such as y type globe valve, Z globe valves and angle types that are designed for specific purposes to serve diverse flow control needs and provide different globe valve functions.
Globe valve symbol is so easy to use and to remember: It’s a colored circle that contains 2 triangles on either side.
This linear-motion valve enables different industries such as pharmaceuticals, aerospace, petrochemicals, etc. to have better control over their systems.
What are different globe valve parts?
Now that you know what a globe valve is, let’s dive into a detailed explanation about different globe valve parts and learn their function in a globe valve, one by one.
No matter what type of globe valve you have, there are several key parts that all globe valves contain: body, seat ring, cage, bonnet, stem, and plug (disk).
The body is the main structure of the valve that keeps everything together. This part contains all internal parts of the globe valve to allow the control of the substance that needs regulation. The opening of the body contains ports (usually two or three ports) to enable the movement of the fluid to the inside or outside of the globe valve.
The seat is among other globe valve parts that seal the space between the disk/stem and bonnet. Seat ring can be screwed into the valve or torqued. The seat is also known as seat ring and provides a shutoff surface that’s stable and also replaceable. Seat rings can hold the cage firmly to the body of the valve.
Cage is also a globe valve part that we already mentioned its name while we explained the function of the seat ring! This cage has been designed to surround the stem and the plug within the globe valve. The cage is among the parts that determines the flow within the globe valve. With the movement of the plug, the flow can increase or decrease. Based on the layout and the design of the openings, the flow of the material inside the valve differs.
Another task that cages are responsible for is to help guide the plug to the seat to provide a good shutoff.
The bonnet is one of the outer globe valve parts that’s connected to the body to provide a leak-proof closure. There are different bonnet types such as bolted, screw-in, or union bonnet that are used in different globe valves. Each of these bonnet types has its own advantage. For example, the union bonnet not only adds strength to the body, but is also great for the applications that need regular cleaning or inspection. The screw-in bonnet with its simple design offers a pressure-tight seal. And the last bonnet type, the bolted bonnets that are attached with bolts are great for higher pressures.
The stem is part of the globe valve that connects the disk to the handwheel or the valve actuator to transmit the actuation force. Since it connects the actuator to the parts inside of the globe valve, it is considered as one of the critical globe valve parts. If the valves are controlled by actuators, the stem is smooth but for the manual valves, they are threaded.
The ends of a smooth steam are threaded allowing the connection to the actuator and the plug. A wearable packing surrounds the smooth stem to prevent leaking material from the valve. So, the packing should be replaced regularly in the maintenance period. The stem can withstand a large amount of compression force in the closure state. And when the valve is opening, it has high tensile strength.
The plug or the disk is among the essential globe valve parts. It moves perpendicular to the seat and its movement can block or free the flow since it works as a moveable physical barrier. When the valve is closed, the plug sits against the seat to block the flow and when it sits above the sits and enables the flow of the material.
Different disk arrangements have been designed for globe valves such as composite type, ball type, and needle type. The composite disk can provide better shut off, while the ball type is used for low-temperature and low-pressure systems. The needle disk has the advantage of providing a better throttling compared to the other two.
Advantages and disadvantages of globe valves
Each valve type has certain advantages as well as disadvantages. Among the advantages of the globe valve, we can mention the fast operation due to its short stroke length as well as easy repair and maintenance since the disk and seat can be accessed from the globe valve top. Another advantage of using a globe valve is that it works well for frequent operation due to its materials. It also provides a better shut off compared to other valves.
Every good device has disadvantages too! When globe valve parts are large, resulting in a larger globe, it requires considerable power and also increases the noise when it’s activated. Another disadvantage of the globe valves is that they are heavier compared to other valves with the same purpose.
That’s all there is to know about globe valve parts and their function! Do you know any details that can help our readers expand their knowledge on the subject? Then comment below and share your experience with us and our readers. And if you have any questions, feel free to sign up on Linquip and one of our experts will answer your questions right away.