Inspection Requirements for Pump Impeller Materials

Impellers used in chemical process pumps, centrifugal pumps, corrosion-resistant pumps, and slurry pumps require specific corrosion resistance under certain operating conditions. Therefore, the requirements for material smelting and inspection differ from those for ordinary heat-resistant steel castings. The following explanation uses a 1.4563 (X1NiCrMoCu31-27-4) pump impeller as an example to illustrate the relevant material requirements:

 

First, the smelting process: VIM+ESR vacuum induction melting + electroslag remelting ensures low carbon content and low impurity content in the casting material.

 

Second, the cast pump impeller requires solution heat treatment and surface passivation or electrochemical polishing to improve its resistance to intergranular corrosion, thereby extending its service life.

 

Finally, material inspection includes chemical composition spectral analysis and intergranular corrosion testing. The pump impeller surface must not have casting defects that could induce crevice corrosion, stress corrosion, or affect structural strength. Machined surfaces should be smooth, free of sharp notches, folds, oxide scale, and foreign matter.

 

There are many other issues to consider regarding the production and inspection of pump impellers, which we will discuss next time.