Selection of Materials for Rotary Seal Valve

The performance of the sealing material used in rotary seal valve is the key to determine the sealing and service life of the rotary feed valve. The temperature range of the rotary valve is very large，and due to the large difference between the linear expansion coefficient of the hard alloy and the linear expansion coefficient of the metal matrix, the internal stress caused by the temperature change is larger when the system is overhauled, it requires larger tensile strength of the cemented carbide. The hard alloy and metal do not infiltrate the atomic structure of stainless steel and WC-Co cemented carbide is different. The WC-Co cemented carbide is mainly composed of ion bond and covalent bond, and the 316 stainless steel is mainly composed of metal bonds. The bonding between 316 stainless steel and WC-Co cemented carbide has a bond type conversion and matching, and they are almost not infiltrated. Therefore, the joint is difficult to achieve a good connection strength through common welding to connect stainless steel and WC-Co cemented carbide, so we need to find a reasonable connection method to achieve a reliable connection between the seal and the base of the rotary valve.

In order to verify the effect of the internal stress of the matrix on the cemented carbide seal ring, we choose WC-Co superfine crystal cemented carbide as the sealing material of the rotary valve. First, heat the cemented carbide seal ring and the metal matrix to 300 C and then cool them to the room temperature.

According to the design standard of the valve, after the valve parts are finished according to the design requirements, we need to inspect the reliability of the valve after the installation of the principle from the bottom to the top, from the inside to the outside. Usually the test procedures are as follows: after the installation is completed, the valve body need to run the shell seal leak test. We need to find whether there are defects or improper coordination problem of the valve parts in the process and assembly process and. Then precisely grind the rotary valve hard seal to ensure the sealing effect. After rotary valve installed distribution, the accuracy and safety of the operation procedure of the valve should be verified for more than 3 hours. After the whole inspection is unmistakable, the leakage test of the simulated working condition should be carried out to verify the reliability of the valve.