Inspection and repair of inline sewage pump parts
The inspection and repair of parts are divided into mouth ring, impeller, balance device, shaft seal device, pump shaft, bearing, pump body and etc.
A. Mouth ring (also known as seal ring)
The role of the mouth ring is to form a narrow, tortuous path between the impeller and the pump casing to increase the flow resistance of the medium and reduce the leakage of the medium. The setting of the mouth ring also protects the main parts of the pump from wear. After the ring is worn, the new ring can be repaired or replaced, and the normal assembly clearance can be restored, which is economical and easy to repair. The integrity of the mouth ring and its radial problem with the impeller should be checked first when disassembling the pump. If the groove has a defect such as a groove or has been broken, or the gap 艿 exceeds the specified value, replace the new ring or repair the original ring. When the pump is in operation, the corresponding circumference of the ring and the impeller wears at the same time, causing the gap to increase beyond the specified value, because the inner diameter of the new ring should be prepared according to the outer diameter of the impeller inlet, and the radial between the impeller and the ring Gap regulation. In the repair process, this gap is required to be smaller to improve the pump's working efficiency and extend the service life.
B. The repair welding steps are as follows:
1) Brush the dirt off the mouth ring.
2) Wash and activate once with a 5% by mass hydrochloric acid.
3) Dip in a caustic soda solution with a temperature of 90 ° C and a mass fraction of 10%, and then wash it in water at 90 ° C.
4) Repair welding alloy. Preheat the ring to about 100 °C, properly weld the original alloy on the split ring with gas welding, pre-cast the electrode with the same alloy as the original alloy, and evenly weld it along the circumference or longitudinal direction of the ring (not repeated) Re-welding). Once the weld is complete, it can be machined to the required standard size. If the alloy is peeled, detached, or worn out too much to repair with repair, re-cast the alloy. After the new ring is installed, check that the clearance between it and the impeller meets the requirements. At the same time, check the two for friction. The method is to apply red lead powder to the rotor and then rotate the rotor. If the red ring powder is on the ring, it must be repaired.
C. Impeller Replacement of the impeller may cause some damage through the impeller used, and the impeller should be replaced. Cracks appear on the impeller surface. The impeller surface forms more perforations due to corrosion, erosion or cavitation. The impeller cover and the blade are thinned due to the scouring, which affects the mechanical strength. The mouth ring of the impeller has a more severe eccentric wear phenomenon without any repair value.
Repair of the impeller:
1) If the impeller corrosion is not serious or there are not many sand holes, it can be repaired by repair welding. The copper impeller is repaired by brass, and the cast iron impeller can also be repaired by brass.
2) The method of repair welding is to clean the parts to be welded before welding to remove oil, rust, scale and so on. It can be preheated locally or whole to 250-450 °C. The welding powder is generally selected from powder 301. The welding wire is usually made of wire 224 silicon brass welding wire. The gas welding flame should be a slight oxidation flame or neutral flame. The welding method is generally used to reduce the overheating of the weld metal and improve the weld. In the formation, in the operation, the direct contact between the high temperature flame core and the molten pool metal should be avoided as much as possible to avoid the generation of pores in the weld metal. After welding, the insulation is slow and cold to eliminate stress and improve performance. After cooling, it can be machined.
