Everything You Need to Know About Bellows Seal Globe Valves

What Is a Bellows Seal Globe Valve?

A bellows seal globe valve is a specially designed valve that is highly suitable for industries dealing with hazardous substances. The valve’s unique design ensures that even the smallest leakages, which can be extremely critical in certain industries, are prevented. This is particularly important in industries such as the chemical and nuclear industry, where there is a high risk of leakage, explosion, and health hazards due to the flow of flammable, hazardous, extremely poisonous, and toxic media through the pipelines. The bellows seal globe valve, therefore, meets specific stringent leakage and sealing requirements that are essential in such industries.

How Do Bellows Seal Globe Valves Work?

Bellows seal globe valves work by using a compact structure that includes bellows for sealing the valve stem components. The bellows valve has a bellow inside, and the lower end of the stainless-steel bellows is welded to the stem to prevent the system fluid from eroding the stem. The other end is positioned between the body of the valve and the cover of the valve to create a permanent seal. This double seal configuration eliminates leakage. Even if the bellows collapse, the stem packaging will prevent further leakage. The bellows are welded to the valve stem to ensure stable operating efficiency and prevent the vibration of the valve stem induced by the movement of the valve insert.

What Are the Key Components of Bellows Seal Globe Valve?

The cast steel bellows seal globe valve consists of body, disc, stem, bonnet, bellows seal, and packing. The valve body is the primary component that houses the valve disc, which controls the flow of media. The valve stem connects the valve disc to the actuator or handwheel, which opens or closes the valve. The bonnet covers the stem and packing and the bellows valve provides a seal to prevent leakage. The following is the photo of bellow seal globe valve.

Types of Bellows Seal Globe Valve

There are several types of bellows seal valves and globe valves available in the market, each with unique design features and applications. Here are some of the most common types of bellows seal globe valves:

Welded Ends bellow seal globe valve

This type of valve has welded metal bellows that provides a flexible, leak-proof seal and protects the stem from corrosion. Welded ends bellows seal globe valves are ideal for high-temperature and high-pressure applications.

Flanged bellow seal globe valve

This type of valve has a flanged connection that makes it easy to install and remove. Flanged bellows seal globe valves are suitable for applications that require frequent maintenance and inspection.

din globe valve with bellows

Socket-welded bellows seal globe valve

This type of valve has socket-welded connection ends which are suitable for high-pressure applications.

Threaded bellows seal globe valve

This type of valve has a threaded connection that makes it easy to install and remove. Threaded bellows seal globe valves are commonly used for small pipeline.

Extended bellows seal globe valve

This type of valve has extended bellows that provide additional protection against corrosion and allows the valve to operate at extreme temperatures and pressures.

api globe valve with bellows

Y Pattern Bellows seal globe valve

The Y-Type Bellows Seal Globe Valve is an exceptionally secure and reliable component, featuring a double sealing structure of bellows and packing. This ensures complete protection from any potential leakage at the stem, making it ideal for use in pipelines carrying dangerous, flammable, explosive, toxic or valuable substances. Additionally, its construction ensures tight seals are maintained under high temperatures and pressures, while also minimizing any risk of leaks.

Applications of Bellows Seal Globe Valve

The bellows seal globe valve is widely used in industries where leak-proof and corrosion-resistant valves are required. Some common applications of the bellows seal globe valve are:

• Chemical industry: The valve is used to control the flow of chemicals, acids, and other corrosive media.

• Petrochemical industry: The valve is used in refineries and petrochemical plants to control the flow of various media.

• Pharmaceutical industry: The valve is used in pharmaceutical plants to control the flow of sterile media.

• Food and beverage industry: The valve is used to control the flow of food-grade media, such as milk, juice, and beer.

Advantages of Bellows Seal Globe Valve

• Zero Leakage: The bellows seal provides a leak-proof seal that prevents fluid from leaking out of the valve.

• Corrosion-resistant: The bellows seal protects the stem from corrosion, which extends the valve’s lifespan.

• Maintenance-free: The bellows seal design eliminates the need for maintenance, which reduces downtime and lowers operating costs.

• High temperature and pressure resistance: The bellows seal globe valve can withstand high temperatures and pressures, making it suitable for use in a wide range of applications.

How to Select the Bellows?

1. Inner Diameter: The inner diameter of the bellows should be greater than the stem diameter, typically 115 mm. This allows the stem to move freely within the bellows without causing any damage.

2. Outer Diameter: The outer diameter of the bellows is usually selected based on the inner diameter. The ratio of the outer to the inner diameter is generally between 113 to 115.

3. Wall Thickness, Number of Layers, Corrugations, and Length: These specifications should meet the requirements of pressure resistance, stroke, and cycle life of the corrugated pipe, ensuring that the bellows can endure operational pressures and temperatures.

4. Bellows Design: For handling higher pressures, a multiply design of bellows (using 2 or 3 piles of the metal wall) is recommended.

5. Material: The material of the bellows components should be selected based on the allowable temperature range, formability, welding performance, and compatibility with the medium. This guarantees the longevity of the bellows in various operational conditions.

What Causes Leakage in Bellows Seal Globe Valves and How Can It Be Prevented?

Conclusion

In conclusion, bellows seal globe valves are an essential component in many industries due to their superior sealing capabilities and robust design. They offer numerous advantages, including enhanced safety, environmental protection, and energy conservation. However, it’s important to select the right bellows and take necessary precautions to ensure safe and efficient operation.