How to determine the degree of corrosion in sewage pumps
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Based on the previously mentioned common types of corrosion in sewage pumps and their impacts, the degree of corrosion can be determined using the following methods: Visual inspection; disassembling the pump to examine the flow-through components – mild corrosion is indicated by only a small amount of rust on the surface, with no obvious defects； Moderate corrosion is characterized by uniform thinning and localized pitting ； Severe corrosion results in perforations, component fractures, and large-area ulcerative peeling. Evaluation of operational performance: The more severe the corrosion, the more significant the drop in the pump’s flow rate and head. When performance falls by more than 20% below the design values, it indicates that the corrosion is quite severe ； Along with abnormal vibrations and increased noise, it can also assist in identifying component imbalance caused by corrosion. Professional instrument testing: Ultrasonic thickness gauges are used to regularly measure the wall thickness of the pump casing and impeller, and the corrosion rate is calculated by comparing it with the original dimensions ； The corrosion level of metal materials can also be accurately determined, as well as their remaining service life, using methods such as weight loss testing and electrochemical measurements. Seal integrity check: If there is only slight leakage, it is due to seal aging caused by mild corrosion ； If the seal fails completely and the pump body develops perforations and leaks, it indicates that corrosion has reached a severe level, and the machine must be stopped immediately for repair.
The method for making judgments shared by the original poster is very practical; combining visual inspection with performance parameters is indeed a reliable approach. I have also encountered problems with corrosion of sewage pumps, and I would like to share two pieces of practical experience: the frequency of regular inspections is very important. If the pump is used to transport acidic or chloride-containing wastewater, it is recommended to conduct an visual inspection at least once per quarter. Detecting moderate corrosion early allows for timely replacement of parts, thereby preventing sudden shutdowns that could disrupt production. Performance degradation is not necessarily due solely to corrosion. Factors such as impeller blockage, motor aging, and changes in pipeline resistance also need to be ruled out; it is best to consider operating current and vibration data together, as relying solely on flow rate and head can lead to misjudgments. Furthermore, pumps made of different materials (such as 304 stainless steel and duplex steel) have significantly varying levels of tolerance. The concept of \"minor corrosion\" mentioned by the original poster should be determined based on the specific composition of the medium involved; it would be more accurate to measure the pH value and chloride concentration if possible. The above are merely personal experiences; the actual procedures should be based on the equipment manual and the conditions at the site. It is safer to consult the pump manufacturer’s technicians when necessary.