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Kaplan Turbines

ADVANCED
CONSUMABLES

GREAT CAVITATION
RESISTANCE

IMPROVE PART
SERVICE LIFE

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Hydropower is a controllable renewable energy source with great potential to enable the transition towards a decarbonised economy but for the most part repair and maintenance is the biggest job on any Hydropower plant. Due to extreme working conditions and operational processes associated with the Hydropower industry, plant equipment is constantly exposed to multiple types of wear on an ongoing basis. High cavitation, erosion and vibration-related wear occurs on the scroll casing, guide vanes and runner blades, that necessitates wear protection management.

To mitigate the range of wear challenges Hydropower plants face, our Welding Alloys technical experts have designed specialised cladding wires, a range of weld cladding equipment and proven restoration processes.

Kaplan Turbines

In 2019 Welding Alloys was approached by a hydropower plant customer in Brazil, in critical need for a more sustainable solution to repair their deteriorating turbines.

The customer operates two large Hydropower sites, one located at the Jirau Dam on the Madeira river and another at the Santo Antonio Dam in Amazonas. This is a large-scale operation with a combined turbine count of 50 between the two sites.  The customer undertook turbine repairs at a rate of every three years, to counter the significant wear the equipment experienced. Over the years, various solutions were implemented but the service life remained the same, which was a disappointment to the customer who was assured of improved performance by suppliers.

To illustrate the extent of wear these turbines experienced, customer data showed that due to the harsh conditions, the turbines at the Santo Antonio Dam were losing 1kg of metal, caused by cavitation, daily. Simply put, turbine repairs would require 1.5 tons of specialist welding wire to complete the job, adding significant costs to an already costly operation.

During our wear audit and analysis of the products and environment, we concluded that the wire used to repair the turbines was not tailored and suitable for combating cavitation and erosion, hence the substantial metal losses. On closer analysis, we discovered that the water pressure on the turbine blades was extremely high and a significant contributing factor to the excessive wear experienced.

Challenge

Extend the service life of the part combating extreme cavitation and erosion

Solution

Welding Alloys metal cored wire

Result

Improved service lifetime and reduced downtime

For several years Welding Alloys provided services and a range of wires to hydropower plants in similar environments across the globe, providing our team in Brazil with valuable reference data from past projects. After completion of the wear audit and data gathering, Welding Alloys proposed the use of two different wires to repair the turbines. Firstly, CAVITALLOY which is a metal cored wire, uniquely designed to fight cavitation and erosion featuring a slag free deposit. And secondly, CHROMECORE M 410NiMo, which is also a metal cored wire designed to be easy to operate with no defects and a slag free deposit. This also requires less preheating opposed to standard wires, all of which combined thereby drastically reducing the welding time.

Since CAVITALLOY does not require post weld heat treatment, the customer was able to benefit from reduced time spent on repair and maintenance projects. However, the most significant outcome of the Welding Alloys solution was an increased service life of up to 10 times, compared to the standard alloys used within the hydropower industry.

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