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Gas Turbine Rotor Blade Lock Machining

 
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Overview

Gas turbine rotors are designed so their blades are replaceable. These rotor blades have a prescribed working life and it is therefore necessary that these blades are changed at intervals as part of statutory outages.

Scope

The blades are arranged in rows. At each row the blades locate into a circumferential T-slot, with spacers between each blade. The final spacer has a wedge mechanism that locks the whole row in position. Releasing this wedge had proven extremely problematic for the Client on previous outages, where they had to resort to manual & difficult to control methods to remove them. MOSS were asked to devise a controllable method of machining away the locking spacer.

Challenges

A method of machining away the locking wedge had to be determined. It was essential that the rotor body remained untouched by the machining process. The blade changing activity was on the outage critical path.

Solution

A process was devised to machine away the locking spacer in stages, allowing the Client to attempt to remove it between stages, and thus carry out the least amount of machining possible.

Achievements

MOSS successfully relieved the stuck wedges allowing the Client to carry out the blade change within program. The rotor body remained untouched.