Fit and forget these bearings for months or even years

There is one less thing for hydro engineers to worry about when designing dams. This is if they choose Vesconite Hilube speciality polymer bearings which can be fitted and forgotten about for months and even years.

This has been the experience of several engineers working on hydropower projects, including recent ones in North and South Africa. The one in North Africa involved the installation of control arm linkages on the radial deep sluice gates on a hydropower dam on the Nile River seven years ago, while the one in South Africa, which is nearing completion, involves the use of Vesconite Hilube trunnion bearings on the tainter gates at the Kruisvallei Hydro Power Plant on the Ash River.

The engineers on both projects were particularly pleased with the fact that the bearings will perform reliably over many decades since they exhibit low creep, i.e. they do not deform under persistent mechanical stress. Vesconite Bearings has undertaken in-house testing and verified that its polymer is unlikely to deform even where significant stress is applied over a long duration. In a test exposing a predetermined Vesconite Hilube test piece to a 30MPa load over several days, no dimensional change was detected. It is the no-creep characteristic that is particularly sought after in these hydro applications since the bearings are fully statically loaded because of the significant water load that constitutes largely applied stress. Vesconite Bearings engineer Juan Van Wyk notes that sleeve bearings that are manufactured from speciality no-creep polymers such as Vesconite Hilube outperform traditional roller bearings, for instance, since these are prone to brinelling or permanent indentation of the rollerballs into the race of the bearing. While Vesconite Hilube bearings remain dimensionally stable under high load, roller bearings can be problematic. Another attractive feature of Vesconite Hilube bearings in hydroelectric applications is that they swell resistant since the speciality engineered polymer that they are made from exhibits a confirmed negligible 0.13% mass change after 28 days of being fully immersed. Vesconite also doesn’t soften under these saturated conditions; hence, its resistance to creep. This means that, where other materials may swell to the point where they do not allow for oscillation where this is required, Vesconite Hilube will reliably hold its shape and, in turn, its small clearances and allow oscillation when this is needed.

For Wicus Bonnet of Eigenbau, the contracting firm that is responsible for the hydro-civil, hydro-mechanical and power-house facilities at the South African project, this was ideal.