Why Sealing Surfaces of Forged Steel Ball Valves Are Damaged?
Forged steel ball valves are mainly used for gas pipelines in urban areas, long-term petroleum pipelines and natural gas pipelines. The security, the weather resistance and the long-term working capability of the forged steel ball valves, and the pressure resistance capacity of the pipelines needs to be fully considered in the process of designing this kind of valve, since these theses valves are usually used for the long-term pipelines. The operation modes of the forged steel ball valve include worm gear drive, pneumatic drive, electric drive and pneumatic-hydraulic drive.
The forged steel ball valve has good high-temperature resistance and wear-resistance. Meanwhile, it is one of the hard-sealed ball valves.
The elastic force of the valve seat on both sides makes the valve seats seal the valve ball tightly. With cemented carbide as the sealing material, the forged steel gate valve can adopt the valve ball with the spray welding coating and finally obtain high hardness. Meanwhile, when the gap between the valve seat and the valve body is sealed by graphite, the working temperature of this kind of ball valve can be up to 425℃.
With cemented carbide as the sealing material and valve ball with the spray welding coating, a forged steel ball valve can adopts the valve body made of chromium-molybdenum steel and have has the working temperature up to 500℃.
The sealing surface of the ball valve‘s body can be damaged easily because of the friction, the collision and the crush when the valve is being opened and closed As a result, the sealing surface will have the indentation crack or concentrated wear. Under high pressure, the adhesion phenomenon occurs between two sealing surfaces of the forged steel valve. The sealing surfaces will be broken when moving. Moreover, the more rougher the surface is, the more the phenomenon occurs.
The abrasion, the water erosion and the cavitation erosion of the forged steel valve‘s sealing surface can easily occur when the media flow inside the valve. This phenomenon is called washout of the media and it always brings the partialy damage to the valve . Thus, the sealing surface of the forged steel ball valve is required to have good quality so that the valve can be resistant to corrosion and erosion of the media.
Besides the normal wear and tear, there are also anthropics factors relevant to the damage of the sealing surface. The anthropic factors include imprecise manufacturing, improper materials, poor designs and maintenance as well as incorrect installation and usage.
All in all, these factors should be avoided so as to lengthen the operating life of the forged steel ball valve.
Source: China Ball Valves Manufacturer – Yaang Pipe Industry (www.ugsteelmill.com)