Failure on Bearing Cooler Coils Connector of Hydroelectric Power Plant

Abstract

Bearing cooler coils connector of 175 MW hydropower plant experienced premature leaks after one year operation and caused an unscheduled shutdown. To avoid the same failure in the future, the leaking bearing cooler coils connector was investigated. Nondestructive tests, such as chemical composition analysis, hardness test, metallographic test, characterization of the filler brazing by scanning electron microscopy – energy dispersive X-ray spectroscopy were conducted. The results confirmed that the bearing cooler coils connector consisted of two types of material namely the flange material which was made of stainless steel 304 and the pipe material which was a Cu/Ni 90/10 and were joined together using brazing process. It was a clearly evidence that leaks occurred in the brazing area and the leakage was due to improper brazing process. It was shown by the excessive gap and a lot of porosity.

Research on Oil Mist Leakage of Bearing in Hydropower Station: A Review

“…Heat buildup may cause bushing bearing failure. Two well-known solutions are the following: the deliberate shutdown of the power stations [9][10][11] to avoid safety risks, complicating Along with this bearing load capacity growth, however, there is increasing concern over the inevitable oil throwing from the tank in the form of oil droplets and oil mist leakage due to the centrifugal force and high temperature [7]. This rise in temperature is due to viscous shear stress due to the enormous pressure applied in the oil film [8].…”

“…Heat buildup may cause bushing bearing failure. Two well-known solutions are the following: the deliberate shutdown of the power stations [9][10][11] to avoid safety risks, complicating the power grid management; and the use of high-temperature bearing designs, as found in the minority of power plants, such as Bratsk Hydropower Station [12], ROSEIRS Hydropower Energies 2022, 15, 2632 3 of 24 Station [13], Karot Hydropower Station [14], and Orujie Hydropower Station [15]. Some common events of oil mist leakage by bearings in power stations are shown in Table 1.…”