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EDM Provides Exact Drilling

EDM Provides Exact Drilling

Frarendi EDMs the cooling holes in its coupons for repairing first stage nozzles of land-based gas turbines.

As the land-based gas turbine industry has evolved, repair and maintenance of key first-stage nozzle components have become highly complex processes built on precision engineering. One of the integral advances in technology is the addition of EDM cooling holes that allow gas turbines to run at higher temperatures with increased efficiency levels. These holes cool the exterior surfaces, protecting the nozzles from high combustion heat while using a minimum amount of air to maintain efficiency.

“To the untrained eye, they look like small holes,” said Kevin Davis, president of Frarendi Inc., a combustion service hardware innovator.

Gas turbines require an extreme level of precision, so the cooling holes must be drilled to exact specifications, size and position. If they aren’t, the efficiency of the turbine is compromised, and its entire nozzle lifespan is jeopardized.

Nozzles become damaged and fail due to constant erosion from high heat and other factors. These include structural fatigue from extended operating periods, using fuels with high levels of impurities, thermal forces and inadequate cooling, mechanical failures, hot corrosion and damage caused by foreign objects. Repair shops worldwide have struggled to recreate these precision holes on eroded or damaged first-stage nozzles, and Frarendi’s coupons, with pre-drilled EDMed cooling holes are a solution.

The company offers two exclusive lines of FSX-414 alloy products and a special method for quickly, easily and cost-effectively repairing firststage gas turbine nozzles. Its trailingedge replacement coupons are also known as wishbones, tips or nozzlereplacement sections.

Frarendi coupons make it possible to cut out, remove and replace eroded sections of nozzles rather than replacing the entire nozzle. They rival the lifespan of original parts and extend the life of the entire nozzle, saving time and money. The company serves OEMs and aftermarket repair, service and machine shops worldwide.

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