PTFE thrust bearing conversion improves operations at hydropower station

Michell Bearings has completed a PTFE (polytetrafluoroethylene) conversion of white metal thrust pads at a hydroelectric power plant in the state of Tennessee in the U.S.

Constructed in the mid-1930s, the 110-MW Norris Dam facility was the first major project for the Tennessee Valley Authority (TVA). Its purpose was to bring economic development to the region and control the flooding that had long plagued the valley.

TVA worked with Michell Bearings after experiencing numerous thrust bearing failures over the life of one of the two turbine-generator units. The failures of the original white metal bearings resulted in excessive downtime and associated loss of revenue.

Michell Bearings was awarded a design contract to investigate the potential problems with the 1930s design, which had been subject to various attempts over the years to improve reliability. The engineers at Michell Bearings created a 3D model of the thrust bearing support structure and performed a finite element analysis to determine any issues affecting the bearing’s performance.

Michell Bearings’ in-house performance prediction software was used to evaluate the performance of the existing white metal pads.

The bearing’s thrust pads were replaced using a PTFE-lined alternative as a result of the study. The PTFE material provides a greater safety factor when compared with the white metal solution. PTFE is more durable and has a well-established and proven track record within the hydropower sector. The study concluded that the material will also increase the life of the bearing and provide greater reliability.

“Although the original contract was awarded as a study, we were pleased to hear that our advice was taken on board and led to the supply of the PTFE thrust pads for the Norris unit,” said Steve Dixon, chief executive officer at Michell Bearings. Previously engineering director, Dixon took on the role of CEO in May 2020. “We have been researching the advantages of PTFE for over 20 years and so we were confident that the material would solve TVA’s problem.”

Michell Bearings and TVA are working on additional projects at the Cherokee and Douglas hydropower plants. Michell Bearings will be presenting a paper on the findings of this project at HYDROVISION International in June 2021.

Michell Bearings has been manufacturing products including horizontal bearings, vertical bearings and tilting pad bearings for the industrial, commercial marine and naval markets for 100 years.

Visit the Michell Bearings website for more information.

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