Segmented Shaft Seals
Tough, abrasion resistant Thordon SXL segmented shaft seals offer several technical advantages over carbon graphite-based seals:
- Ease of installation as carbon segments are quite fragile and can break easily
- Provide extended wear life if abrasives are present
- Increased capability to handle transient loading at startup and shutdown
- Easy installation and misalignment tolerance
- Supplied molded to size
Operating parameters for Thordon SXL segmented shaft seals are generally similar to those for carbon graphite seals in terms of maximum interface pressure and minimum leakage rate. Thordon segmented shaft seals have been designed for shafts up to 2000mm (80") diameter. They can be designed for use in either radial or axial sealing systems.
The main shaft seal of a turbine usually operates under high PV-value conditions and may also be frequently exposed to abrasives in the water. Thordon segmented shaft seals are a proven solution working in both clean and abrasive laden water.
Based on Thordon's R&D testing and field experience, Thordon segmented shaft seals are able to operate in a wide range of PV-values with the maximum water pressure tested up to 0.7 MPa (100 psi).
Depending on the shaft size, number of segments, machining precision of segments, sealed water pressure and shaft speed, the amount of leakage can vary widely. It is difficult to predict the leakage rate accurately at the design stage. However, R&D testing has confirmed that for a radial segmented seal consisting of 6 segments running on a 400 mm (15.75") diameter shaft, the leakage rate would be from 10 to 40 l/min (2.6 to 10.6 US gal./min).
Additional advantages of the segmented seal design include easy installation and replacement without removing the shaft. Disassembly of other machine parts may not be required.