Seal Protection of Rotary Valve

The pipeline system with hard erosion medium will wear the valve and pipe strongly. In order to enhance the service life of the equipment, a layer of wear-resistant material is usually added to the inner wall of the equipment. In addition, the valve must have adequate sealing performance, once the mechanical sealing surface is damaged, the valve will soon become invalid. Usually there are two reasons for damage to the seal surface of the valve, which are artificially damage and natural damage. Artificial damage is usually including poor design, poor manufacturing, improper material selection, improper installation, poor use, and poor maintenance. Natural damage is the wear and tear of the valve under normal working conditions. It is the damage caused by the medium to the inevitable corrosion and erosion of the sealing surface.

In the pipeline system with hard particles, except the artificial factors, the damage of the seal surface is usually caused by the erosion and wear of the medium, which is the results of the wear, erosion and cavitation on the sealing surface when the medium flows. When the medium is at a certain speed, the floating fine particles in the medium collide with the seal surface to cause local damage. The high-speed flow medium directly scours the seal surface to cause local damage. When the medium is mixed and local vaporization, it produces the bubble, which blasts impact on the surface of the seal surface, resulting in the damage of the local damage. The erosion and the chemical corrosion of the medium will alternately corrode the sealing surface strongly. The mechanical damage of the seal face is caused by Rubbing, touching, squeezing, etc. in the process of opening and closing. Between the seal surface, the atoms interpenetrate with each other under high temperature and high pressure, resulting in adhesion. When the two seal surfaces are moving, their adhesion is easy to tear. The rougher the surface of the seal surface is, the more likely the phenomenon will happen. During the closing process, the disc will be bruised and squeezed on the seal surface during the closing process, so that the seal surface can be worn or indented locally. Fatigue damage, seal surface in long-term use, under the action of alternating load, resulting in fatigue surface, cracks and stripping layer.

Therefore, in order to achieve the sealing effect of the valve and increase the service life of the valve, the inner wall of the valve body and the seal face should have high wear resistance and erosion resistance, and the wear resistance of the surface is usually adopted at home and abroad. Common methods include surface laser cladding, supersonic flame spraying, surfacing, and wear-resistant parts.