Radial segmented shaft seals play a vital role in the reliable operation of large hydro turbines, which can feature shaft sizes ranging from 400 to 2000+ mm (16 to 80 inches). Understanding the specific leakage pathways within these seals is critical, particularly when considering the varying designs and material compositions used in modern sealing solutions. 

Given the structural and operational complexity of these seals, understanding their leakage pathways is essential for predictive maintenance and design optimization: 

1. Segmental Interaction Points

The interaction points between segmented carbon rings, especially in the tongue and groove areas, are critical leakage pathways. The design of these areas, particularly in the context of the seal’s three-stage construction, necessitates precise engineering to minimize leakage. The introduction of higher-pressure injection flow between the first and second rings not only aids in lubrication and cooling but also serves as a preventive measure against abrasive ingress, thereby influencing the leakage dynamics. 

2. Dynamic Sealing Interfaces

The area where the seal contacts the rotating shaft is of paramount importance. Utilizing materials like SXL enhances the seal’s resistance to wear and abrasion, thus reducing the likelihood of leakage. The seal’s design, incorporating a garter spring, ensures consistent pressure against the shaft, minimizing the gap and, consequently, the leakage potential during both operational and downtime periods. 

3. Static Sealing Interface

The seal’s contact with the housing introduces another potential leakage path. Despite the seal’s design to conform to the housing under differential pressure, this interface can never be perfectly sealed. Understanding the material properties, such as those of SXL, helps in predicting the seal’s behavior under varying pressure conditions and aligning the seal design accordingly to mitigate leakage.