Wellhead Non-Rising Stem Gate Valve for Oil & Gas Operations

 
The wellhead non-rising stem gate valve is a crucial fluid control device in the oil and gas industry, specifically designed for high-pressure operating environments. This valve enables precise fluid control through manual operation using a handwheel. Renowned for its exceptional sealing performance and reliability, it is widely used in wellhead operations. The wellhead gate valve integrates an advanced floating seat structure and high-performance materials, ensuring it can withstand harsh conditions while maintaining long-term stable operation.

Operating Principle

 
The operation of the wellhead non-rising stem gate valve primarily relies on the trapezoidal thread transmission mechanism between the stem and gate. When the operator turns the handwheel, the stem drives the gate to move up or down, thereby controlling the opening and closing of the valve. This design allows the valve to provide efficient fluid control without the need for additional power. The valve seat features a floating symmetrical structure, which balances inlet and outlet pressure when fully open. A wave spring between the seat and valve body automatically corrects the gate's position, ensuring proper reseating. When fully closed, the high-pressure medium pushes the gate towards the outlet side, achieving seat sealing. Simultaneously, the inlet seat is pushed towards the gate by the high-pressure medium and spring force, creating the necessary sealing pressure, further enhancing the sealing effect.

Key Components

 
The wellhead non-rising stem gate valve is composed of several critical components, including the valve body, seat, gate, stem, wave spring, bonnet, packing, bearings, bearing bracket, gland, and handwheel. The stem is positioned by the bearing bracket and bearings, ensuring precise and stable movement. The lower end of the stem is connected to the gate via trapezoidal threads, forming an integrated gate structure. This design effectively prevents sediment in the pipeline from entering the valve body cavity and minimizes flow resistance when the valve is fully open by aligning the flow guide hole in the gate with the pipeline bore.

Fluid Control and Energy Efficiency

 
When fully open, the guide hole in the gate of the wellhead non-rising stem gate valve aligns with the pipeline bore, allowing fluid to flow smoothly through, preventing turbulence and maintaining the same pressure drop as the pipeline. This design excels in energy efficiency, making it particularly suitable for gas injection processes. Additionally, the full-bore design of the gate ensures that downhole tools and instruments pass through without sticking, further protecting the valve's sealing surface from damage and reducing erosion caused by fluid velocity.

Floating Seat Design

 
The floating seat structure is a standout feature of the wellhead non-rising stem gate valve. The effectiveness of the seal between the seat and gate largely depends on the seat's floating capability. The seat can float axially and radially to prevent galling or seizing between the seat and valve body. To achieve this, a wave spring with high expansion compensation performance is installed between the seat and valve body. This structure not only prevents the seat from seizing during operation but also ensures a good fit with the sealing surface, providing excellent sealing performance even at low pressures.

Thrust Bearing and Stem Structure

 
To further enhance ease of operation, the stem nut is equipped with two high-load-capacity thrust bearings, which effectively absorb the load during gate opening and closing, significantly reducing the torque required to operate the handwheel. Additionally, the seat is fitted with a guide plate, eliminating the possibility of gate misalignment during operation. The stem features a non-rising design, ensuring that internal cavity pressure does not increase during operation and preventing the transfer of lubricant.

Surface Treatment and Material Selection

 
To enhance corrosion resistance and anti-scratch performance, the sealing surfaces of the wellhead non-rising stem gate valve undergo hardening treatment. The seat and gate are made from materials with similar or identical coefficients of thermal expansion to ensure the stability and reliability of the sealing surfaces under varying conditions. Additionally, the sealing surfaces are treated with a nickel-based alloy powder spray welding process, which not only enhances the valve's corrosion resistance but also improves its wear resistance, extending its service life.

Applications and Advantages

 
The wellhead non-rising stem gate valve is widely used in high-pressure fluid control at oil and gas wellheads due to its precise design and high-reliability sealing performance. Its floating seat structure, thrust bearings, and non-rising stem design ensure excellent performance under various harsh conditions. Whether in high-pressure gas injection processes or environments with stringent sealing requirements, this valve delivers outstanding performance, ensuring efficient and safe fluid management.
 
In summary, the wellhead non-rising stem gate valve, with its precise design, excellent sealing performance, and durability, is an indispensable piece of equipment in the oil and gas industry. Whether facing the challenges of high-pressure fluid control or operating in harsh environments, this gate valve consistently demonstrates superior performance, providing robust support for the safety and efficiency of wellhead operations.