The advantage of plug valve application is that the valve body installed on the top of the whole is equivalent to the ball valve installed on the top of the whole. Compared with two-piece or three-piece ball valve, it is a completely different type and application product.
Let us understand the advantages and disadvantages of the plug valve and the main purpose of the plug valve:
1. The valve body adopts an integrated top installation design, with simple structure, convenient online maintenance, no leakage of the valve body, and high strength of the piping system.
2. The medium in the chemical process is very corrosive. In a chemical environment, the valve body is often corroded by the medium. Therefore, the valve body used in the chemical process must have strong impermeability. In addition, the valve body of the plug valve is resistant to intergranular corrosion and is a g-class casting. The quality of the castings is Grade 2 and the accuracy is Grade 5
3. The opening and closing part, namely the cock, is completely covered by the bushing, the valve body and the cock are not worn out, and the bushing and top seal can be replaced easily and economically. You can complete the maintenance and renewal of 300 valves. Compared with the metal hard seal ball valves in this range, °C has a clear competitive advantage in long-term use.
4. The entire machined surface of the plug valve is only the top surface and flange, and all other parts are cast in one time. There is no treatment in the valve body. Compared with the ball valve, it has the advantage of small handling capacity.
5. The plug valve can be designed to perform specific functions according to user needs. The plug valve is an ideal choice for customer-specific valve products. The plug valve makes it easy for you to customize the process. It can adapt to three-way, four-way, five-way, six-way, double-valve or multi-valve group, and various sheath requirements. For example, the six-way distribution valve used in the polyester industry is a plug valve customized according to the requirements of the patentee, which increases the difficulty of the ball valve as a customized valve.
6. At present, the plug valve has no gap or end face seal. Ball valve design with or without clearance, but only the design of the ball valve can keep the clearance between the valve ball and the valve body between 1 to 3 mm. The benefits of coating surface sealing applications cannot be realized. Due to this feature of the plug valve, the plug valve is easy to crystallize and viscous, and is suitable for handling many harsh media, such as fluid corrosion and deposits containing catalytic particles.
7. The coated bushing has surface sealing performance, which can strictly control the "zero leakage" test requirements of the API598 soft seal seat, and can meet the requirements of TA-Luft or iso15848 valve stem sealing. The general characteristics of plug valves are long service life and high reliability. It is suitable for a variety of corrosive, abrasive, toxic, continuous operation and other media and equipment, and has the advantages of application in the chemical industry. Wide range of applications.
Disadvantages of plug valve
1. The surface seal design increases the requirements for driving torque. For pneumatic actuators, the use of actuators and accessories larger than ball valves will increase the user's cost. For example, in the PP process, the main stop valve uses a plug valve instead of a ball valve, and the high-frequency switch valve uses a ball valve, so the pneumatic plug valve is basically used in the main cut-off position. I will. It is not entirely recommended to use a plug valve during adjustment. High-frequency switching is not an advantage of plug valves. High reliability stop valve.
2. In some applications, improper selection of the bushing material or improper valve body design will cause the PTFE bush to expand and cause the required driving torque of the valve in the bushing deformation release zone to change many times. In order to draw proper materials and have strong pertinence, this situation is basically avoided.
3. The one-time investment of the plug valve is higher than that of the ball valve. However, as the reliability of the plug valve and the total life cycle cost are gradually accepted by domestic users, more and more users will need a plug valve that continues to use the original process design, and the decision to switch to a ball valve will gradually decrease.