Installation and Maintenance of Flanged Gate Valves

Flanged gate valves are widely used in industrial applications due to their excellent sealing performance, simple and reliable structure, and durability. However, high-quality valves alone cannot ensure long-term stable operation of the system. Proper installation and maintenance are essential to ensure their performance. This article provides a comprehensive guide, covering preparation, installation steps, and maintenance, to help you maximize the functionality and advantages of flanged gate valves.

Preparation Before Installation

Proper preparation is essential before installing flanged gate valves. This ensures that the valves meet the application requirements and that the installation process proceeds smoothly.

1. Valve Inspection

Before installation, the user must check the valve's model, specifications, markings, and nameplate. The user should confirm that these meet the requirements of the working conditions. The user must also verify that the connection dimensions match the pipeline and that the flow direction aligns with the valve design.

2. Valve Cleaning

Cleaning is a critical step during installation. The user should thoroughly clean the inner chamber and sealing surfaces of the valve to remove dust, sand, or other debris. Debris can cause poor sealing or operational issues. When using metal gaskets, the user must ensure the flange face is free of damage or scratches. The user should also ensure that the flange groove fits the gasket and apply red lead for grinding to achieve a proper seal.

3. Checking the Sealing Surface

The user must carefully inspect the valve's sealing surface, bolt connections, packing compression, and valve stem rotation. Properly tightened packing components ensure both the valve's sealing performance and operational flexibility.

4. Confirming Installation Position

The user must ensure that the valve is installed in a location that facilitates future inspection and operation. The valve should be easily accessible and should not interfere with the normal use of other pipeline equipment.

Installation Steps for Flanged Gate Valves

The user should follow these steps to ensure the valve's sealing performance, stability, and long-term reliability.

1. Aligning Flange Faces

For gate valves with flanged ends, the user must align the connecting flange faces during installation. The valve and pipeline connection surfaces should be perpendicular and aligned. The flange faces should be parallel, with a proper gap, avoiding misalignment or tilting. If a gasket is used, the user must place it correctly to avoid skewing.

2. Bolt Tightening

The user must tighten the bolts symmetrically and evenly during installation. Uneven tightening can cause residual stress and affect the seal. The user should follow a symmetrical and alternating sequence while gradually applying torque. The user should use appropriate tools and avoid exceeding the specified torque. When using hydraulic or pneumatic tools, the user must be careful to prevent over-tightening.

3. Checking Sealing Effectiveness

After installation, the user must check the valve's sealing performance. The bolts and nuts should be properly tightened without any looseness. For high-temperature valves, the user should re-tighten the connecting bolts, valve cover bolts, and packing gland bolts after the temperature rises to maintain proper sealing.

4. Reserving Operating Space

The user must ensure there is sufficient space around the valve for operation, especially for valves with actuators. For valves with drive devices, the user must strictly follow the wiring diagram during installation to ensure proper operation of the actuator.

Special Installation Considerations for Flanged Gate Valves

In specific operating conditions or special environments, the installation of flanged gate valves requires careful attention to certain key details to ensure safe operation and optimal performance. Below are the installation precautions for flanged gate valves in special scenarios.

1. High-Temperature and Low-Temperature Installation

High-Temperature Valves: For valves operating above 300°C, the user must re-tighten flange bolts, cover bolts, pressure seals, and packing gland bolts after the temperature increases to compensate for expansion.

Low-Temperature Valves: For low-temperature valves, the user must consider thermal contraction effects. Flanges, gaskets, and bolts may shrink at low temperatures, and materials with different thermal expansion coefficients may cause leaks. The user must apply appropriate torque considering these factors.

2. Avoiding Forced Connections

The user must avoid forcibly tightening the flanges during installation. Forced connections can cause residual stress, leading to poor sealing or operational difficulties. The user must ensure all bolts are evenly tightened during installation.

3. Gaskets and Sealing Rings

The user must ensure that metal gaskets or other sealing rings are properly positioned, flat, and evenly lubricated with materials such as red lead. This enhances sealing effectiveness.

4. Material Selection for Flange Bolts

The user must select flange bolts and nuts according to standard requirements. The materials must withstand high temperatures, low temperatures, or corrosive environments. The user must ensure material compatibility to avoid looseness or leaks caused by improper materials.

Inspection and Maintenance After Installation

After installation, the user must conduct a comprehensive inspection to ensure proper valve function.

Pipeline Flushing and Pressure Testing: The user must fully open the valve and flush the pipeline, followed by pressure testing of the system. The user must confirm there are no leaks and that the system reaches the required working pressure.

Long-Term Maintenance and Inspection: The user must regularly check the condition of the flanged gate valve. This includes inspecting the sealing surface, packing condition, and valve stem rotation. The user must promptly address any issues to ensure proper valve operation.

Conclusion

Correct installation and maintenance of flanged gate valves ensure sealing performance, operational flexibility, and extended service life. This reduces system risks and maintenance costs. In both regular working conditions and special environments, following proper installation procedures and regular maintenance plans is essential. With proper management, flanged gate valves can serve as core equipment for pipeline system safety and efficiency, providing continuous support for industrial production.