There should be an anti-static mechanism at the joint of the stem and the sphere and at the contact of the stem and the valve body to prevent the static electricity from gathering on the sphere. Stem safety design should prevent "blow-out" under working pressure, and the flange on the stem should be disposed of as a ring ring to reduce friction coefficient.
Characteristics of Traditional Stem Processing Technology
1. The screw flying cutter is used in traditional valve stem threads, which leads to inaccurate thread accuracy, while the traditional chip-free rolling die is easy to be damaged, deformed and distorted.
2. Grinding machine is not accurate and time-consuming.
3. Double clamping and pull-down seal is used in the reverse part, which is poor in concentricity and easy to leak.
4. The end part is indexed by milling machine indexing plate, which is slow in processing, multi-process and time-consuming.
The characteristics of valve stem manufacturing process:
1. The new type of valve stem thread is extruded by self-made, which has high thread strength and accurate accuracy.
2. The concentricity of the threaded part and the polished rod part overcomes the problem of twisting and fragility of the rolling die which has troubled the domestic rolling process for a long time.
3. The precision of light rod position achieves mirror effect, easy to open and close, and good sealing.
4. NC technology is used to form the reverse part at one time, which has high precision and good sealing performance.
5. The T-groove at the end is forged with high efficiency and low cost.
6. The whole production process of valve stem has reached the international advanced level.
Under the strong corrosion, volatile and harmful process conditions, once the stem seal is damaged, the strong corrosion, volatile and harmful process medium leaks out from the control valve stem, which will bring serious consequences to the surrounding environment and personal safety. Using bellows valve stem seal is a way to solve the above problems. Bellows are usually made of stainless steel. This special valve cover structure protects the packing box of the control valve from contact with the fluid. Once the bellows break, the packing box structure above the bellows will prevent serious consequences when the bellows break down and fail. In engineering practice, the pressure rating of bellows should be fully considered in the selection of bellows seal form. The pressure rating of bellows seal will decrease with the increase of temperature. There can be no solid particles in the fluid, and the longest cycle operating life of bellows material. In places where stainless steel is not resistant to strong corrosion of some process media, such as wet chlorine gas, trace hydrochloric acid in wet chlorine gas will cause stainless steel bellows to be corroded quickly.
In progress, the development of science and technology is also faster and faster. The new manufacturing technology of valve stem reduces the cost, improves the work efficiency and meets the requirements of modernization. In addition, bellows globe valve manufacturer prompted that the selection of stem material is also an important work in its production process, I hope not to ignore this important factor. Provided by Sanjing Valve Technology Department
