Two Common Methods to Improve the Service Life of the Upper Seal of Globe Valves
Globe valves are essential components in industrial pipeline systems, valued for their simple structure and ease of operation. Their unique working principle—combining rotary and linear movement of the valve stem—enables reliable opening, closing, and sealing functions. However, this motion generates not only the necessary vertical pressure between sealing surfaces but also harmful relative sliding friction. In practice, the upper seal often fails after just a few cycles due to scoring. Minor damage requires disassembly and repair, while severe cases lead to valve scrapping, increasing manufacturing costs and compromising system reliability. To address this, improvements have been made to both the structure and materials of the upper seal.The main stop valve product names of China Stop Valve Network include:GB Cast Steel Flange Globe Valve,GB Stainless Steel Flange Globe Valve,High Temperature and Pressure Power Station Electric Globe Valve,Insulation Globe Valve,Oxygen-specific Globe Valve,Pneumatic Flange Straight-through Globe Valve,Self-sealing Straight-through Globe Valve,Y-type Jacket Insulation Globe Valve.
Structural Improvement: Relocating the Upper Seal to the Disc
By transferring the upper sealing function from the valve stem to the disc, the upper sealing surface on the disc remains stationary relative to the bonnet during operation, eliminating sliding friction. This structural modification significantly extends upper seal life. However, it introduces an additional seal between the disc cover and the disc, adding complexity and reducing cost-effectiveness.
Material Improvement: Hardfacing with Stellite Alloy
Applying a Stellite alloy hardfacing to the valve stem’s sealing cone surface enhances galling resistance and improves sealing performance. Nevertheless, this approach has drawbacks: Stellite alloy is expensive, and the 13Cr martensitic stainless steel stem material offers poor weldability. The hardfacing process requires preheating, post-weld insulation, and additional rough machining to maintain dimensional accuracy. Except for special applications, this method also suffers from low cost-effectiveness.
Feasible Solution: Increasing Valve Stem Cone Surface Hardness
Practice has shown that increasing the hardness of the valve stem cone surface offers a practical and economically viable solution. With relatively simple processing and controlled costs, this method effectively reduces leakage risk, extends valve service life, and enhances product reliability—making it suitable for widespread adoption in standard valve applications.
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