Comparison of hard seal ball valve and soft seal ball valve

September 22, 2021

1. Structural mechanism The hard seal of the ball valve is the seal between the metal and the metal. The seal ball body and the valve seat are all metal. Processing accuracy and process are more difficult, generally used in high temperature or high pressure, suitable for granular media. Soft seals are seals between metal and non-metal, such as nylon/PTFE, and the manufacturing standards are the same.

2. The soft and hard seal on the seal material is the seal material of the valve seat. The hard seal is precisely processed with the valve seat material to ensure the accuracy of the valve core (ball). Generally, stainless steel alloy steel carbide is used. Soft sealing means that the sealing material embedded in the valve seat is a non-metallic material. Since the soft sealing material has a certain degree of elasticity, a relatively hard sealing will be required for processing accuracy.

3, due to a lot of chemicals in the manufacturing process, the mechanical industry's working environment is more complex, many are high temperature and high pressure, medium friction resistance, strong corrosion, and now the technology has improved, the use of various materials is better, processing Can keep up with other aspects, so that the hard seal ball valve has been widely promoted.

In fact, the principle of hard seal ball valve and soft seal is the same, but because of the seal between the metal, to take into account the hardness relationship between the metal, as well as working conditions, what medium to take and so on. Hardening treatment is generally required, and the ball and the valve seat must be constantly ground to achieve sealing. The hard seal ball valve has a long production cycle and the processing is more complicated. Therefore, the price of the hard seal ball valve is much higher. 4. Generally, the soft seal can achieve high sealing in the use conditions, and the hard seal can be high or low according to the requirements; the soft seal needs fire protection. Because in the high temperature, the material of the soft seal will leak, but the hard seal does not have this problem; The hard seal can generally do the very high pressure, the soft seal does not work; The soft seal is due to the problem of flowing medium, some occasions are Can not be used (such as some corrosive media). As far as manufacturing is concerned, the difference between the two is not significant. The main difference is the valve seat. The soft seal is non-metal, and the hard seal is metal.

5, in the equipment selection above the soft and hard seal ball valve selection based on the process medium, temperature and pressure, the general medium contains solid particles or wear or temperature is better than 200 degrees the best choice for hard seal, caliber greater than 50 valve pressure difference Large also consider the size of the valve to open the moment, the larger the moment should be used fixed hard seal ball valve, regardless of the soft and hard seals can reach the level of its six sealed.

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Mr. Zheng

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zheng@rmiplast.com

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