SHIP REPAIR | TURBINE BLADE and NOZZLE RING REPAIRS:
SHIP STORE is often able to repair damaged turbine blades. This is done by a specialized procedure carried out by highly qualified technicians. The turbine blades are dismantled, cleaned ultrasonically and accurately measured. An UV inspection is then carried out to determine whether there are any fractures present. New ones replace fractured blades.
Under certain strictly controlled conditions, we are welding using a procedure developed through extensive research by metallurgists and SHIP STORE engineers can repair the turbine blades. The method used is TIG (Tungsten Inert Gas) welding: a technique using a non-fusing electrode at low amperage shielded by an inert gas. Only a small zone may be exposed to heating, and the operation must be carried out in a closed welding chamber , free from dirt particles and air turbulence, as any draught will disperse the shielding gas, resulting in a poor welding result.
Following the repair the blade is machined, and ground back into its original shape and inspected for cracks using UV/penetrant inspection, and the weight is then checked. In order to achieve the correct weight distribution, a computer is used to determine the sequence, in which the blades should be mounted on the rotor , which is then ready for balancing.
SHIP REPAIR | DYNAMIC BALANCING:
Before a rotor can be balanced, it is first necessary to check the run out of the shaft and the deflection of the compressor wheels is still within the permitted tolerances. If these measurements are satisfactory or after remedial work, the rotor is examined for imbalance on a microprocessor controlled test bench, according to the ISO 1940 standards. Rotor shaft on balancing machine. The complete rotor is placed on the balancing machine and the partition wall is independently supported.
Even though imbalance may not have been evident before overhaul and calibration, it is possible that it could be introduced during dismantling and repair procedures and it is therefore paramount that dynamic balancing is carried out before the rotor is returned to service. If the imbalance is found to exceed the permissible value, it is corrected by grinding down the appropriate correction planes on the rotor . Accurate balancing is of the utmost importance and not a single rotor leaves the Compmarine workshop without having been tested and, if necessary, corrected. All balancing are recorded, and reported as per enclosed reports with components.