Gate Valve

1. Body
This is the main pressure-retaining part of the valve and contains other operational parts such as the gate and seat. Moreover, it provides passage to flow from the valve and is connected to the piping on both ends. A variety of connections including threaded, flange, butt weld, compression fitting, and tube fitting can serve in connecting the body to the piping. Selecting the best connection type is key and is determined by client’s specifications, valve size, and operating pressure.
 

2. Bonnet
The bonnet provides another pressure-retaining part that encloses and protects a gate valve’s stem and wedge. Generally, connects and disconnects from the body to provide access for the repair or maintenance of internal components. Common body-bonnet connections include:
• Screwed Bonnet: This simple body-bonnet connection offers quick access into the valve. However, they are limited to small size gate valves and low-pressure applications. When used in these applications, screwed bonnets can deliver a long-lasting, leak-proof seal and easy disassembly.
• Union Bonnet: In this design, a union nut rests on the lower edge of the bonnet, and screws into the threads of the valve body. As a result, it prevents the leak-proof seal from deteriorating over time. This more robust connection provides a better option than the screwed bonnet when operators require frequent bonnet removal.
• Bolted Bonnet: As valve sizes get larger and the working pressure increases, using flanges and bolts becomes necessary. This robust connection requires a gasket to seal the body-bonnet joint.
• Welded Bonnet: This option works well for designs where the operator does not require the disassembly of the body bonnet. It offers a much lighter assembly than the bolted bonnet and operates in the same pressure range.
• Pressure Seal Bonnet: A pressure seal bonnet is specifically for high-pressure applications in excess of 1,500 psi (103 bar). It has a unique mechanism where the operation pressure helps to improve the body-bonnet joint seal as the internal pressure increases. Typically, it is used alongside bolts and flanges.
 

3. Gate
The gate, sometimes referred to as a disc or obturator, moves to either obstruct or allow flow through the valve. There are several types of gate designs and technologies depending on the application’s requirements. Design types include:
• Wedge gate: This common gate utilizes a wedge-shaped disc, which sits or rises from two inclined seats to obstruct or allow flow respectively. It is ideal for applications where there is high flow or turbulence such as steam service.
Because of its shape, frictional seat wear is minimal rubs and thus sticks under high differential pressures. As a result, it lasts longer than most other types of gates. In the case of high temperature, a flexible wedge gate provides a better option than a solid gate and prevents thermal locking as well.
• Slab gate: The slab gate provides a through-conduit gate and derives its name from its design. It is a single-piece gate containing a bore-size hole that aligns to the pipe bore when in the open position.
As a result, it provides a smooth turbulence-free flow, making it ideal for systems that require minimum pressure loss. Although the valve seat often remains debris free, the disc cavity is prone to catching foreign materials. Thus, slab gates usually include a plug to remove these materials during maintenance.
• Knife gate: Whenever flow contains plastic solids and high-viscosity slurries such as paper pulp, a knife gate provide an effective option. The knife gate enables it to cut through these materials and stop the flow.
• Parallel Slide gate: The parallel slide gate works well in high-pressure and temperature applications in which with their internal springs feature located between both discs, helps the disc to be in contact with the seat rings and prevent thermal expansion.
 

4. Seat
A gate valve has two seats that interface with the gate to ensure the sealing of the valve. These seats come either as part of the body or in a seat ring construction. When the seat is part of the body, then they are both made of the same material. Whereas in a ring construction, the seats threads or presses into position before welding onto the valve body. This method allows for more variation than in integral seats, and provides the preferred method in high-temperature applications.
 

5. Stem
The stem’s forged shaft transfers motion from the actuator to the gate when closing or opening the valve. A gate valve uses either a rising or non-rising stem.
• Rising stem: A rising stem connects directly to the gate and rises when opening the valve, and lowers when the valve is closing. As a result, they contain built-in visual indicators and are easy to lubricate due to their exposed threading.
However, they contact the flow medium, increasing threading corrosion and debris carryover risk. Also, due to the motion of the stem, they are not suitable for use with bevel gears or automatic actuation.
• Non-rising stem: For a non-rising stem, the disc threads internally to the stem, so it moves up and down the stem for opening and closing. This makes it ideal for applications with space limitations, automatic actuation, and corrosive media.

Zhejiang Bozheng Copper Co., Ltd. is located in the "the valve capital of China"-Yuhuan (a city by the East China Sea in the Yangtze River Delta economic circle). Founded in 1998, the company is a comprehensive enterprise integrating research and development, design, manufacturing, sales and service.

After decades of exploration and development, "Bozheng" has become a high-quality brand in the domestic valve industry. We will continue to provide advanced and stable products and perfect sales services for domestic and foreign users, and strive to serve as a healthy and safe shield to create a safe living environment for each home.

In the course of nearly 20 years of innovation and development, Bozheng people have been adhering to the qualities of fairness, stability, and keeping promises. We increased the investment in hardware and software and built a set of mature and competitive product structures. Our products are widely used in construction, plumbing, gas, chemical, petroleum, electric power and many other industries. With reliable quality, complete varieties, safety and convenience, long service life and other characteristics, the products have won praise and affirmation from the majority of dealers and users alike.