China cast iron globe valve supplier share with you: Cast steel globe valve is a compulsory sealed valve, so when the valve is closed, pressure must be applied to the disc to force the sealing surface to not leak. When the medium enters the valve from below the valve disc, the resistance to be overcome by the operating force is the friction between the valve stem and the packing and the thrust generated by the pressure of the medium. The force to close the valve is greater than the force to open the valve. The diameter must be large, otherwise the failure of the valve stem bending will occur.
In recent years, since the emergence of self-sealing valves, the medium flow direction of the cast steel globe valve has changed from above the valve disc into the valve cavity. At this time, under the action of the medium pressure, the force to close the valve is small, and the force to open the valve is large. The diameter of the valve stem can be reduced accordingly. At the same time, this type of valve is also tight under the action of the medium. China ’s valve “Sanhua Group” has stipulated that the flow direction of cast steel globe valves shall be used from top to bottom. When the cast steel globe valve is opened, the opening height of the valve flap is 25% to 30% of the nominal diameter, and the flow has reached the maximum, indicating that the valve has reached the fully open position. Therefore, the full-open position of the cast steel globe valve should be determined by the stroke of the valve disc.
China cast iron globe valve has a simpler structure than a gate valve, and is more convenient to manufacture and maintain. The sealing surface is not easy to wear and abrasions, and has good sealing performance. There is no relative sliding between the valve disc and the sealing surface of the valve body during opening and closing. Therefore, the wear and abrasion are not serious, the sealing performance is good, and the service life is long. When opening and closing, the valve disc travel is small, so the height of the cast steel globe valve is smaller than that of the gate valve, but the structure length is longer than the gate valve. Closing is more laborious, and the principal of opening and closing time.
The fluid resistance is large, because the medium passage in the valve body is more tortuous, the fluid resistance is large, and the power consumption is large. When the nominal pressure PN≤16MPa in the direction of the medium flow, the flow is generally adopted and the medium flows upward from the valve disc; when the nominal pressure PN≥20MPa, Generally, counter current is used, and the medium flows downward from the valve disc. To increase the seal capacity. In use, the medium of the cast steel globe valve can only flow in one direction, and the flow direction cannot be changed. When fully opened, the disc is often eroded. The stem axis of the cast steel globe valve is perpendicular to the seat sealing surface. The opening or closing stroke of the valve stem is relatively short, and it has a very reliable shut-off action, which makes this valve suitable for use as a medium for cutting or regulating and throttling.

Carbon Steel Stainless Steel Globe Valve

The disadvantages of carbon steel stainless steel globe valve:
The fluid resistance is large, and the force required when opening and closing is large. It is not suitable for media with particles, large viscosity and easy to coke, and has poor regulation performance.
Advantages of cast steel globe valve: Double sealing design (corrugated pipe + packing) If the bellows fails, the valve stem packing will be avoided, and external leakage, and in accordance with international sealing standards, no fluid loss, reduce energy loss, improve plant equipment safety, use Long life, reduced maintenance times, reduced operating costs, rugged and durable bellows seal design to ensure zero stem leakage and provide maintenance-free conditions. The bellows-sealed cast steel globe valve adopts the bellows seal design, which completely eliminates the shortcomings of the common valve stem packing seals, such as aging, and easy to leak, which not only improves the use of energy efficiency, increases the safety of production equipment, reduces maintenance costs and frequent Maintenance also provides a clean and safe working environment.