Improvement of sealing structure and materials on High Pressure Hydrogenation Valve

The High Pressure Hydrogenation Valve has a simple structure. The valve can be opened or cut off by the principle of both rotation and lifting of the Valve Stem, and the sealing and upper sealing functions of the valve can be ensured. Due to the special movement principle of the structure, it also causes extremely unfavorable consequences for the force between the sealing pairs on the valve (forming both the required vertical pressure between the sealing pairs and the friction of relative sliding between the sealing pairs). Practice has shown that the upper seal of the valve is often opened and closed only a few times, and leakage is caused by scratches between the sealing pairs. Minor scratches need to be disassembled and repaired, and serious scratches are scrapped due to damage. Such consequences not only increase the manufacturing cost of the enterprise, but also affect the performance of the valve. In order to solve such problems, the structure and materials of the upper seal of the valve were tested and improved.

① Move the upper sealing part of the valve stem to the valve disc (the purpose is to make the upper sealing surface on the valve disc relative to the upper sealing surface on the valve cover in a static and non-slip state during the force process). Although this improvement can increase the life of the upper seal, the structure is more complicated and the cost performance is low due to the need to add a seal between the valve disc cover and the valve disc.
② Change the material of the upper sealing pair. The method of surfacing welding Stellite carbide with good abrasion resistance on the valve stem sealing cone surface has achieved good results, but on the one hand, the cost of Stellite alloy is too high, and on the other hand, the basic material of the valve stem is 13Cr martensitic stainless steel, which has poor weldability. Preheating before welding and heat preservation after welding are required during surfacing welding, and the welding process is complicated. In addition, in order to ensure the dimensional accuracy of the valve stem, rough processing procedures must be added. Comprehensive analysis shows that this solution is not cost-effective except for special requirements.