Improvement of Stem Seal Structure for Flat Gate Valves

Flat gate valves play a crucial role in fluid control systems across various industrial applications. However, one persistent challenge in their practical usage has been stem seal leakage. To address this issue, thorough research has been conducted, leading to significant improvements in the seal structure of flat gate valves. This article elaborates on the refined seal design and outlines essential considerations for its implementation.

Enhanced Seal Structure

1. In response to stem seal leakage, a multi-layered seal structure has been devised. The primary seal consists of an O-ring, complemented by additional layers of filler seals. The selection of O-ring specifications is contingent upon the valve's pressure rating, with appropriate interference fit or one-way stop ring configurations employed to meet general sealing requirements.
2. The filler seal employs a serial connection structure, strategically designed to withstand the pressures and friction generated during stem movement. Specifically, the lower end face of the upper filler box is pressed against the filler of the mid-flange filler box, while the filler within the upper filler box is compressed by a filler pressure cap. Once the filler boxes are loaded with filler material, axial compression is achieved either through rotating bearing seats or by individual compression methods, ensuring effective stem sealing.

Key Considerations for Improvement

Material Selection: The choice of seal material is pivotal. Optimal elasticity and wear resistance are sought to accommodate the refined multi-level serial structure effectively.
Compression Maintenance: To prolong seal life, maintaining compression across all filler layers is imperative. This compensates for stem-induced wear. Experimental evidence suggests that a single compression event can sustain filler integrity, offering superior reliability compared to multiple compression cycles.
Maintenance Protocol: In instances of stem seal leakage in high-pressure flat gate valves, immediate filler replacement is advised over repetitive compression attempts. For zero-leakage requirements, adhering strictly to prescribed filler lifespan intervals is paramount, eschewing cost-saving measures that entail recurrent compression.
The enhancements made to the stem seal structure of flat gate valves, coupled with meticulous adherence to maintenance protocols, promise to mitigate stem seal leakage effectively. This not only bolsters valve performance but also ensures a more stable and reliable fluid control framework across industrial domains.

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