How to choose the structure and material of the shielding sleeve for chemical process shielded pumps?

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Chemical process shielded pumps generally consist of two shielding sleeves, namely the stator shielding sleeve and the rotor shielding sleeve, which are used to keep the working medium in contact with the stator windings and the rotor core, respectively. It is normal for some problems to arise as chemical shielded pumps are used for longer periods of time. The shield casing is crucial for chemical shielding pumps; if damage to the shield casing is detected during use, it needs to be replaced promptly. Maintenance and inspection of the shield casing of shielded pumps: 1. Objective of shield casing maintenance: The losses in the motors of chemical shielded pumps are significant; the losses in the stator shield casing can be as high as 2-3 times those due to iron losses. The losses associated with the shield casing after maintenance should be maintained at their original level. 2. Manufacturing of the shielding sleeve: The process of manufacturing the shielding sleeve is a challenge in the major overhauls of chemical shielding pumps. High requirements are placed on the dimensional accuracy and shape tolerances of the shielding sleeve, especially the welding quality of the welds, which is also subject to strict standards. There are technical challenges involved in various steps such as calculating the dimensions for material cutting, cutting the material, performing straight-seam welding, rounding the edges, pressing the components together, carrying out ring-seam welding, and conducting leak checks after welding. The gap between the stator and rotor of a shielded pump motor is usually only 0.5–1.0 mm; therefore, it is necessary that the shielding sleeve not only be able to be inserted into the stator and rotor cores smoothly but also fit tightly against them. Only in this way can a proper gap be maintained between the stator and rotor, which requires a high level of technical skill. 3. Overall leak detection of the stator: After welding the stator end plates and casing, inserting the shielding sleeve and completing the welding of the ring seams at both ends of the shielding sleeve, an overall leak detection check should be conducted on the stator. Stator leak detection method: The inner cavity between the frame and the stator shield is filled with air at a pressure of 0.5 kg/c㎡, and then the entire stator is submerged in clean water. If there is a leak, bubbles will appear in the water; this is a simple method for detecting leaks. Material selection for the shielding sleeve: For shielded pumps, the shielding sleeve should be made of a non-magnetic material with good corrosion resistance and high strength. For the stator shielding sleeve, Hastelloy is preferred (usually grade C276 or UNS N10276); for the rotor shielding sleeve, Hastelloy, CHAO-grade austenitic stainless steel, or ordinary austenitic stainless steel are commonly used.