Rework of pump and valve castings
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What considerations are needed when repairing castings? Quality issues with castings purchased from external suppliers are something that pump and valve manufacturers often encounter. So, how should casting manufacturers and pump and valve manufacturers handle the repair of such castings appropriately? Stages at which defects are detected: Casting manufacturer: 1. Cut off the risers and gates; after blasting, conduct a visual inspection. Pump and valve manufacturer: 1. During the incoming goods inspection stage, detect defects that exceed the SP55 requirements, or uneven wall thicknesses. 2. During the machining stage, identify issues such as black skin, cracks, as well as looseness in the sealing surfaces and clusters of pores. 3. During the hydrostatic testing stage, detect leaks in the casting body. Can these defects be repaired by the pump and valve manufacturer? Is heat treatment required for the repair?
Of course it needs to be repaired. But whether heat treatment is necessary depends on the material
Most repairs to pump and valve castings are carried out through welding; for minor repairs, the welding procedures must be followed carefully. For large areas, heat treatment is required, and the mating surfaces need to be inspected and repaired.
If the pump or valve body shows loose areas, sand holes, or pores, the manufacturer needs to replace it; minor issues can be repaired by welding, but those that are too large require replacement. Castings often have such problems, and returning them to the manufacturer for replacement will solve the issue