Difference between soft seal ball valve and hard seal ball valve
If ball valves are classified according to seal, they can be divided into two categories: imported soft seal ball valves and imported hard seal ball valves. Because their sealing materials are different, the product characteristics are also different, and the applicable working conditions and occasions of the products will be different. Combined with the product characteristics of American Weidun VTON, a commonly used ball valve brand, this paper analyzes the differences between the two, so as to help users select the application.
1、 Understand the next two products from their definitions
1. Imported soft sealing ball valve: it refers to that the sealing material embedded on the valve seat is non-metallic material, generally PTFE or plastic materials such as rubber, nylon and graphite, that is, the soft sealing material is used as the sealing material of the ball valve; For example, the soft sealing ball valve of American Weidun VTON brand ball valve with large consumption generally adopts tetrafluoro sealing material.
2. Imported hard seal ball valve: it refers to the ball valve whose sealing ball and valve seat are made of metal.
2、 The difference between the two can be analyzed from the following points
1. Differences in structural characteristics
Soft seal ball valve is a seal between metal and non-metal, such as nylon, tetrafluoroethylene and rubber
The hard seal of the hard seal inlet ball valve is the seal between metal and metal, and the sealing ball and valve seat are metal. The soft and hard seal is for the sealing material of the valve seat. The hard seal is precision machined with the valve seat material to ensure the matching accuracy with the valve core (ball). Generally, there are stainless steel and copper. Soft seal means that the sealing material embedded on the valve seat is non-metallic material. Because the soft sealing material has a certain elasticity, the requirements for machining accuracy are relatively low for hard seal. It is the most common product type of imported ball valve
2. Differences in manufacturing processes
Generally, the soft seal can reach very high, while the hard seal can be high or low according to the requirements; The soft seal needs fire prevention, because the material of the soft seal will leak at high temperature, while the hard seal does not have this problem; Hard seal can generally do high pressure, but soft seal can't; Due to the problem of flowing medium, soft seal can not be used in some occasions (such as some corrosive media); Rear hard seal valves are generally more expensive than soft seal valves. As for manufacturing, there is little difference between the two, mainly the difference between the valve seat. The soft seal is non-metallic and the hard seal is metallic.
3. Differences in selection and Application
From the product performance of the famous ball valve brand American Weidun VTON, we can see that the service temperature of soft seal imported ball valve is generally within 250 ℃, and that of hard seal ball valve can reach 600 ℃; Soft sealing ball valve has good sealing performance, but it is not wear-resistant. The sealing performance of hard sealing ball valve is poor compared with soft sealing butterfly valve, but it is wear-resistant. It is more suitable for media containing particulate impurities.
The difference between imported soft seal ball valve and imported hard seal ball valve is mainly the difference of sealing performance, temperature resistance, wear and erosion resistance; Therefore, taking Weidun VTON, the representative brand of ball valve, as an example, soft seal ball valve is more suitable for clean water, oil and gas at room temperature, while hard seal ball valve is more suitable for high-temperature oil, steam and medium containing particulate impurities