Correction And Welding Repair Technology Of Propeller
Feb 17, 2023
Propeller correction
Propeller correction includes cold correction and hot correction. Both cold and hot correction shall be subject to visual and dye penetrant inspection, and defects shall be repaired. After correcting the propeller with large deformation, recheck whether the pitch meets the specifications.
Propeller welding repair
Repair welding of blade tip welds and missing parts shall be carried out after grinding to eliminate cracks. It is strictly prohibited to carry out in windy and humid environment. In principle, the material shall be the same as the propeller. After the propeller blade is cut and replaced, the pitch measurement and static balance test shall be carried out for batch grinding or correction. Welding repair with cavitation depth more than 1/3 of blade thickness shall be carefully considered and approved by the surveyor.
1. Before welding, the crack and cavitation parts of the blade must be polished, and the number, length and direction of the crack must be determined by dye penetrant inspection.
2. Before welding repair of cracks, the cracks shall be thoroughly excavated (ground), all the cracks shall be removed, and appropriate welding junctions shall be selected for welding repair. Repair welding of blade edge cracks shall be carried out from the central area to the edge side.
3. The oxide and dirt in the edge notch and denuded hole shall be completely removed to expose the metal luster before welding repair.
4. The proper form of welded junction shall be selected for cracks and broken blades.
5. For the broken blades in zone C, the chemical composition B and mechanical property test report of the newly cast and welded block must be approved by the surveyor when the new block is used for butt welding. During welding, the pressure side of the blade should be downward, and the lining plate should be placed under the butt joint. The welded joint should be double-sided U-shaped or V-shaped, and should be fully welded. The welding shall be carried out from the center to the two edges.
6. The preheating device can adopt coke oven, flexible far-infrared heating blanket and propane soft flame spray gun.
