We received the bundle and the rotor inside an airtight container. After dismantling the bundle, we have created a CAD model of rotor, refurbished the rotor (journal bearing repair, NDT, low-speed balancing) and manufactured new labyrinths following APS process.
A client requested replacement of the main oil line getter pump with re-designing of a shaft, impellers, diffusers, a ring section, a balance drum, and a restriction bush. The impellers and diffusers were customized for operation at the required lower flow (65%).
- Reduced flow rate
- Higher temperature
- Dimensions
- X-Ray Material Identification
- Fatigue Zone
- Hardness Testing
- Stress Analysis
- Structurally, the blade hub included a bush which is why the shaft was attached to the conical hub. Our redesign suggested to make a cone shape on the shaft itself. It would help reduce the total number of fan parts, for design simplification, lower the risk of breakage, and decrease the vibration amplitude when using the equipment.
- This solution made us find more suitable bearings instead of the vertical thrust bearings to ensure a stable shaft design. The old bearings P/N 505-09660-11 (ZAS 5203) with ID 55 mm were replaced with the new ones (ZAS 5211) with ID 70 mm.
- To secure the pulley, we decided to add two nuts at the ends of the shaft. The nuts will be notched, which means no risk that they will screw off or strip, even under a heavy load. The nuts will be secured in place with 2-3 grub screws.
- Eroded wear plate and casing inner surface
- Wear plate was removed and found in a deeply eroded condition
- Protection caps faced severe erosion
- Eroded vanes of impeller
- Machining of the eroded surface of pump casing suction nozzle
- Manufacturing of a bushing of the specific size with inner TC surface
- The eroded areas of the impeller vanes were filled with welding.
- Newly fabricated erosion-resistant plate
Concerning the erosion, the recommendation is to coat it with a special erosion/temperature resistant coating to prevent further erosion advancing (statistically, once erosion initiates and gets visible during 2nd overhaul, by the time of 3rd overhaul the amount of accumulated erosion damage leads to a catastrophic failure and renders equipment completely non-recoverable) and to significantly extend the motor life.
- Totally failed mechanical seal
- Cavitation caused erosion on impellers
- Eroded and corroded areas on side plates
- Severe damages on a shaft key slot
OEM recommendation was to scrap the unit, but TECTA DMCC completely repaired it.
- Inner side of casing was carefully polished with a pneumatic brush.
- Impellers were restored.
- The key groove was repaired and the impeller case was polished.
- All spares were covered with TC composite coating.
To perform a deviation check, we decided to compare the old and the new parts using 3D models of power turbine ring pads, bearing pads, and thrust pads. We used ROMER ABSOLUTE ARM for 3D scanning. First, we cleaned and fixed the parts to digitalize them. Then, we processed the results obtained in a form of point cloud data, to make solid 3D models. We aligned them along the major axes to finally compare and find the deviations between the old and the new parts.
- Eroded casing
- Eroded impeller and split flange
- Eroded wear rings
- Bottom bearing found absolutely damaged
- The remaining shoulder parts were machined
- Installation of the special stops on the sides
- Final machining after welding. MPI test proved no cracks or porosity
Reworked seal plates will be installed along with 0.25mm NOVUS SUPRA gaskets
- Sketch of machining of the eroded place on casing
- Eroded places on the pump casing were welded up and carefully machined
- Sketch of the old and new drilled holes of the cartridge. Used cartridge has been previously modified and the new holes drilled.
- All impeller vanes (7 vanes per impeller) were observed to find eroded zones approximately 25-35 mm long and the deepest zone (3.5mm) at the end of the vanes.
- The damaged vanes were welded up and then milled.
