Multi-Stage Steam Turbine Blade Reverse Engineering

A special purpose multi stage condensing steam turbine in a refinery in Saudi Arabia failed during the operation. Upon internal inspection of the compressor, it was found that one of the turbine blades was cracked and needed a replacement.

This turbine is a multistage one which was installed in 1978. The turbine is driving a HCU recycle gas compressor operating at 10660 revolutions per minute (rpm). This is un unspare compressor and in case of failure will cause the entire hydrocracker unit shutdown.

During the Repair process , a crack was found on one of the Turbine Blades. Reverse engineering the blade was the perfect option Due to the long lead time to receive such bucket or new rotor. In order to succeed in this project, we lay down the path forward with all action items to tackle this project starting from scanning the blade all the way to testing and verification, We started with 3d scanning the blade at RE center followed by creating 3d model in order to get professional engineering drawing which can be given to one of the in-kingdom contractor to start fabrication. The material used for the fabrication is SS 410 which is a bit higher grade alloy than the original one which is ASIS 403. As of testing and verification, many tests were performed to the fabricated turbine blade to ensure mechanical properties are within acceptable limits. NDT was performed, MPI, hardness tests, radial and vertical clearances of new blade inserted at turbine wheel and finally natural frequency of new blade.