EnglishWhy Use Extended Stem Valves in Complex Installations
In many industrial settings, you may notice certain valves fitted with long stems—where the actuator is located at ground level while the valve body is buried underground or hidden deep inside equipment. These are known as extended stem valves. Their design is no coincidence; it serves a practical purpose, tailored for installations where space, temperature, or accessibility constraints make conventional valve configurations impractical.
This article will explore the necessity of extended stem valves and explain their value and design logic through two common types: extended stem gate valves and extended stem butterfly valves.
What Is an Extended Stem Valve?
An extended stem valve is a standard valve modified with an extended stem, transmission shaft, or connection tube. This extension increases the distance between the actuator (such as a handwheel, gear operator, or electric actuator) and the valve body itself.
Such a configuration allows operators to open or close the valve from a more accessible location—even if the valve is installed in confined spaces, underground pipelines, or high-temperature zones that are difficult or unsafe to approach directly.
Common types of extended stem valves include:
- Extended stem gate valves
- Extended stem butterfly valves
- Extended stem ball valves
The selection depends on specific working conditions such as installation environment, valve size, control method, and the nature of the media being handled.
Why Do Valves Need Extended Stems?
Extended stem valves are designed to meet special installation and operation needs. They are commonly used in the following four scenarios:
1. Underground or Deep-Buried Installations
In municipal water supply, gas pipelines, and sewage systems, valves are often installed underground or inside manholes. With an extended stem, the actuator can be placed above ground, eliminating the need for operators to enter confined spaces and improving safety.
2. High- or Low-Temperature Systems
In steam lines or cryogenic systems like liquid nitrogen cooling, valve surfaces may become extremely hot or cold. An extended stem moves the operating mechanism to a safer area, reducing the risk of burns or frostbite for personnel.
3. Insulated or Jacketed Systems
In industries such as petrochemical or food processing, pipelines and equipment are often wrapped with insulation or heating jackets. Without an extended stem, operators may need to remove insulation to access the valve, which is inconvenient and affects system stability. Extended stem designs allow operation without disturbing the insulation, maintaining system integrity.
4. Confined or Hazardous Areas
At the bottom of storage tanks, beneath furnaces, or in explosive environments, space is tight and access may be dangerous. Extended stems make it possible to position the actuator in a safe, accessible location—ideal for easier maintenance and remote operation.
Application Example: Extended Stem Gate Valve
An extended stem gate valve is based on a standard gate valve, with a lengthened stem or connecting shaft that allows the actuator (such as a handwheel, T-key, or electric device) to be positioned away from the valve body. This design is especially suitable for buried or hard-to-reach installations. As a shut-off valve, it offers excellent sealing performance and is ideal for pipeline systems that require reliable but infrequent operation.
Key Functions:
1. Remote On/Off Control
By extending the stem, the actuator can be installed at ground level or on an operating platform, allowing remote control of a valve located underground or in a distant location.
2. Improved Safety for Operators
In environments with high/low temperatures, toxic media, or confined spaces, operators can stay away from the hazardous area, reducing the risk of burns, exposure, or injury.
3. Reliable Flow Shut-Off or Opening
Just like a standard gate valve, it controls flow by raising or lowering the gate, providing a tight seal and effective isolation when needed.
4. Suitable for Deep-Buried or Inaccessible Areas
Ideal for installations such as underground chambers, the bottoms of storage tanks, or any area where direct access is difficult. It improves operational efficiency and ease of maintenance.
5. Compatible with Various Actuators
The valve can be operated manually or combined with electric or pneumatic actuators, supporting both manual control and automation requirements.
Application Example: Extended Stem Butterfly Valve
Butterfly valves are known for their compact structure and quick on/off functionality, making them a popular choice in large-diameter pipeline systems. An extended stem butterfly valve modifies the standard design by lengthening the drive shaft, stem, or actuator mount—allowing the operating mechanism (such as a lever, gear operator, or electric actuator) to be positioned away from the valve body. This enables reliable operation in complex or restricted installation environments.
Key Functions:
1. Fast On/Off Flow Control
Butterfly valves feature quick 90-degree rotation for open/close control. The extended stem design preserves this efficiency, ensuring responsive fluid control even over long distances.
2. Remote Manual or Automated Operation
By connecting an extended shaft to the actuator, the valve can be operated remotely via a surface-level handle, gear operator, electric actuator, or control cabinet.
3. Suitable for Extreme Temperature or Insulated Environments
The actuator can be positioned in a temperature-safe zone, protecting both personnel and equipment from heat-related burns or cold-induced damage.
4. Flexible Installation in Limited Spaces
Ideal for installations behind equipment, at height, between floors, or in other space-constrained areas where direct access is difficult.
5. Reduced Maintenance Costs
With the actuator installed in a visible and accessible location, there’s no need to remove insulation, enter underground chambers, or perform complex disassembly—saving time and labor during maintenance.
Advantages of Extended Stem Valves
- Enhanced operational safety – Avoids the need for personnel to enter hazardous or confined areas.
- Remote or ground-level control – Reduces maintenance effort and labor costs.
- Adaptable to complex conditions – Suitable for high/low temperatures, insulated systems, underground installations, and more.
- Flexible, customizable design – Easily tailored to meet the needs of various engineering projects.
Frequently Asked Questions (FAQ)
Q: Are extended stem valves universal? Can they be customized?
A: Extended stem valves are typically customized based on the actual installation environment, especially the required stem length. While the extended parts are made to order, standardized components like connection dimensions and sealing structures usually follow industry standards.
Q: How are buried extended stem valves sealed?
A: Buried valves often come with sealed sleeves and water-stop rings to prevent soil and moisture from entering the stem chamber, ensuring long-term, reliable operation.
Q: Can extended stem butterfly valves be equipped with electric or pneumatic actuators?
A: Yes. The extended stem structure can easily be connected to electric actuators or pneumatic cylinders using a lengthened drive shaft, enabling remote or automated control.
If your project involves buried pipelines, high-temperature systems, insulated equipment, or space-constrained environments, consider extended stem valves during the selection phase. They not only simplify operations but also improve safety and ease of maintenance—a smart structural upgrade for demanding applications.
At Union Valve, we understand that every valve application is unique. That’s why we offer not only standard gate, butterfly, and ball valves, but also fully customized extended stem solutions—including stem length, actuation type, and protective features—based on your project’s specific requirements.
Contact us today to see how Union Valve can be your trusted partner in engineering reliable and efficient flow control solutions.
