A globe valve and a bellows seal globe valve both belong to the family of globe valves, which are used to control the flow of fluids through a pipeline or system. However, the primary difference between them is the presence of a bellows seal in a bellows seal globe valve.
A bellows seal is a flexible metal component that provides a leak-proof seal and protects the stem from corrosion, which makes the bellows seal globe valve more suitable for applications that require high performance and reliability.
Din globe valve with bellows
Din globe valve
Purpose of Bellows in Valves
The primary purpose of bellows in valves is to provide a flexible, leak-proof seal that protects the stem from corrosion and prevents fluid from eroding the stem. Bellows are also used to compensate for changes in temperature and pressure in the system, which allows the valve to operate smoothly and efficiently.
Difference between Bellows Seal Valve and Common Valve
The primary difference between a bellows seal valve and a common valve is the presence of a bellows seal. A bellows seal valve has flexible metal bellows that provide a leak-proof seal and protect the stem from corrosion, while a normal valve does not have this feature.
Meaning of Bellows Seal
A bellows seal is a flexible metal component that is used in valves to provide a leak-proof seal and protect the stem from corrosion. The bellows seal consists of metal bellows that is welded to the stem and a packing gland that secures the bellows in place.
Reason For Bellows
The primary reason for using bellows in a valve is to provide a flexible, leak-proof seal that protects the stem from corrosion and prevents fluid from eroding the stem. Bellows are also used to compensate for changes in temperature and pressure in the system, which allows the valve to operate smoothly and efficiently.
How Bellows Work
Bellows work by expanding and contracting to compensate for changes in temperature and pressure in the system. When the temperature or pressure in the system changes, the bellows expand or contracts to allow the valve stem to move freely, which prevents damage to the valve and ensures smooth operation.
Types of Valve Seals
There are three types of valve seals: packing, mechanical, and bellows.
Packing seals use a flexible material, such as graphite, to provide a seal around the stem. Mechanical seals use a rotating component to provide a seal, while bellows seals use a flexible metal component to provide a leak-proof seal and protect the stem from corrosion.
Two Types of Valve Seals
The two basic types of valve seals are static and dynamic. Static seals provide a seal between two stationary components, while dynamic seals provide a seal between two moving components.
Disadvantages of Bellows
One of the primary disadvantages of bellows is that they can fail over time, which can lead to leakage and other issues. Bellows can also be more expensive than other types of valve seals, which can make them less suitable for certain applications.
Bellows Failure
Bellows failure can occur due to a variety of factors, such as fatigue, corrosion, or mechanical damage. When a bellows fails, it can lead to leakage, reduced valve performance, and other issues. Regular inspection and maintenance can help prevent bellows failure and ensure the continued performance of the valve.
How Does Bellows Seal Globe Valve
The operational principle of a bellows seal globe valve is based on its unique design, which includes a bellows seal that protects the stem from corrosion and prevents fluid from eroding the stem. The valve consists of a valve body, a valve disc, a valve stem, a bonnet, a bellows seal, and packing.
When the valve is in the open position, the valve disc is lifted away from the valve seat, allowing media to flow through the valve. The stem and the disc move together as the stem is rotated by the actuator. When the valve is in the closed position, the valve disc is pressed against the valve seat, preventing media from flowing through the valve.
Comparison of Bellows Seal Globe Valve with Other Valve Types
Parameter
Globe Valve
Ball Valve
Butterfly Valve
Gate Valve
Diaphragm Valve
Bellows Seal Globe Valve
Flow control
Excellent
Good
Good
Not Suitable
Good
Excellent
Leakage
Low
Low
Low
Low
Very Low
Very low(Zero Leakage)
Corrosion resistance
Good
Good
Good
High
High
Very high
Maintenance
Moderate
Moderate
Moderate
Low
Low
Low
Temperature range
-20°C to 500°C
-40°C to 200°C
-20°C to 120°C
-29°C to 425°C
-29°C to 150°C
-196°C to 600°C
Pressure range
Up to 2500 psi
Up to 1000 psi
Up to 150 psi
Up to 5000 psi
Up to 200 psi
Up to 2500 psi
Applications
Water, steam, gases, oils
Water, gases, oils
Water, air, gases
Steam, water, gases, oils
Slurries, viscous fluids, corrosive chemicals
Corrosive fluids, high temperature, and high pressure applications
