1. The China pump parts are generally cast iron shelled while the stainless steel one is for corrosive media. The case may crack under the action of the mechanical force, the thermal stress, the cavitation impact and the frozen water inside. For the irreparable damage, replace for new ones. It will be quite a long life for the shell to serve if it is of excellent quality under normal use.
Never classified as vulnerable parts, the pump case, including the body and the cover, is free from the standings.
2. The pump shaft is generally of carbon steel like S45C, 2Cr13 and so on. The China pump parts are prone to be damaged with cracks, bends, journal wear, thread stripped, fracture accidents and so on due to its quality, use, or installation. Replace a new shaft for an irreparable one.
3. The sleeve, as a protector to the shaft, will be subject to friction between the packing and the shaft if it is a packing seal one. Therefore, it is suggested to have a mechanical sealed sleeve for friction-free protection. However, in case that the failed mechanical sealing rubs the sleeve, it is recommended to be part of the vulnerable kept in standing stock.