Ultra-high Pressure Self Pressure Sealing Forged Gate Valves

In the development of gate valves, the United States has always taken the lead. In the 1960s, the United States began to study the high-pressure gate valve with 105MPa. With the increase in pressure, the structure of the gate valve has also undergone tremendous changes, from a rising stem to a non rising stem. In the 1970s, research on the gate valve focused on materials and processes, and now a series of materials and process forms of gate valve parts have been formed; in the 1980s, gate valves are developed in the direction of higher pressure and more reasonable structures; in the 1990s, the research on gate valves was toward the development of automation design, compact structure, small sizes and higher pressure.
 
The forged steel gate valve controls the flow in the pipeline. A gate valve is widely used for water, oil, natural gas, food and other industries due to the characteristics of low flow resistance, flexible opening and closing, long service life, compact structure, safety and reliability. The demand for forged steel gate valves is increasing day by day due to the rapid development of China's industry and the development of export markets, which requires valve manufacturers to continuously improve their processing technologies, striving to increase production capacity under the premise of ensuring product quality.
 
In response to market demand, production efficiency and product performance and quality of forged gate valves are greatly improved by developing new sealing structure and packing of valve bodies, new handwheels and fixtures for valve bodies. The forged steel gate valves can compete with similar products at home and abroad, and quickly occupy the market.
 
The ultra-high pressure self-pressure sealed forged steel gate valve is a kind of valve used to control the medium in the pipeline. Once this series of valves fail in the operation, leakages and rupture of valves will occur, resulting in economic losses and posing a great threat to personnel safety. In view of the defects of existing products, the research on the following part were conducted based on a large number of tests and analyses and the latest advanced literature at home and abroad.
 
1. The design of the sealing of the valve body's middle cavity
The sealing of the middle cavity of the valve body relies on the pressure of the medium acting on the end face of the stuffing box to make the sealing ring sealed under pressure. The higher the medium pressure is, the better the sealing performance becomes. Stainless steel is adopted for the sealing ring, instead of graphite to make the sealing more stable.
 
2. The design of thrust bearing
In order to reduce the coefficient of friction in the opening and closing process of the valve, two thrust bearings are provided between the valve stem nut and the valve bonnet, so that the opening and closing process can be smooth.
 
3. The design of the packing of the stem
Graphite is one of the commonly used materials for the sealing of valve stems. The packing will be lost after being scoured by the pressure medium for a long time. If the packing is not filled in time, the packing force will be decreased and failures will occur, which is easy to cause the leakage of the medium. The forged steel gate valve adopts an eyelet bolt structure loaded by a disc spring to make up for this deficiency and ensure the sealing effect of the packing.
 
4. Design and research of the calibrate tool of the gate valve's sealing 
The calibrate tool of the gate valve's sealing can make the copper ring or steel ring in the designated position inside the gate valve. A standardized clamping position can improve the internal sealing performance of the gate valve, and increase the service life of the gate valve under the same conditions.
 
5. The design of the handwheel
When the valve's opening and closing torque is great under high pressure, the opening and closing by the common handwheel will make your hands uncomfortable. The handwheel used in this article is an outer corrugated oval hand wheel, which is better and more humane.
 
6. The design of the fixture for the valve body
A new type of fixture for the valve body is designed. The valve body that needs to be tooled is placed on the base and then the clamping bolt is used to rotate. The clamping bolt pushes the fixture to move down along the mounting block so that the fixture clamps the valve body. At this time, the staff can use both hands to tool the valve body. When the tooling is completed, turn the clamping bolt in the opposite direction to move the fixture upwards, and take out the valve body completed by the tooling from the base, thereby improving the tooling of the valve body. It is convenient to fix the valve body, and make the hands of the staff not tied, so that the staff can perform tooling on the valve body with both hands at the same time, and improving the efficiency of the tooling of the valve body.
 
Key points of innovation

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