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In the operation and maintenance system of urban infrastructure, municipal pipelines and sewer pipelines are the “underground veins” that ensure the normal operation of cities, undertaking the important mission of rainwater discharge and sewage transportation. For a long time, the inner walls of pipelines are prone to accumulate sediment, oil stains, construction waste and biological deposits, which not only reduce the flow capacity of pipelines and cause frequent blockages, but also may lead to a series of safety and environmental hazards such as sewage overflow, road collapse and water pollution. Traditional pipeline cleaning methods mostly have disadvantages such as low efficiency, easy damage to pipelines and environmental pollution. However, high-pressure water cleaning technology, with its core advantages of high efficiency, environmental protection and non-damage, has become the mainstream solution in the field of municipal and sewer pipeline cleaning, providing reliable support for the operation and maintenance of urban underground pipe networks.​

High-pressure water cleaning technology, also known as high-pressure water jet cleaning, its core principle is to pressurize ordinary clean water to 15-25MPa (which can be increased to higher pressure under special working conditions) through a high-pressure pump, form a high-speed jet through a special nozzle, and use the impact force, shear force and water wedge effect of the water flow to quickly peel off the deposits and attachments on the inner wall of the pipeline. At the same time, the pollutants are pushed to the downstream inspection well by the thrust of the water flow, and then concentrated pumped and disposed of by the sewage suction equipment, so as to achieve thorough cleaning of the pipeline interior. Compared with traditional methods such as manual dredging, chemical cleaning and mechanical scraping, high-pressure water cleaning does not need to add any chemical agents, only uses clean water as the medium, avoiding the damage of chemical pollution to soil, groundwater and the surrounding environment from the source, which is in line with the current green and environmental protection concept of urban development.​

In municipal pipeline cleaning, high-pressure water technology shows strong adaptability and high efficiency. Municipal pipelines have a large span of diameters (mainly DN300-DN1600mm) and complex lines, covering various scenarios such as main road drainage pipelines and industrial park rainwater and sewage pipelines. Some pipelines have been in use for more than 10 years, with a high proportion of branch pipes and prominent silting problems. High-pressure water cleaning can flexibly adjust pressure parameters and nozzle types according to pipeline diameter and sediment type. Direct-injection nozzles can accurately break stubborn blockages, and fan-shaped nozzles can realize all-round flushing of the inner wall of the pipeline, effectively removing various sediments such as sediment, oil stains and root intrusion. For example, in the industrial zone of Xinjie Town, Yixing, Wuxi, the high-pressure water cleaning technology is used to maintain 15 kilometers of rainwater and sewage pipelines. After cleaning, the recovery rate of pipeline flow capacity reaches more than 90%. The flow capacity of a 600mm diameter sewage pipe of a chemical enterprise is increased from 120L/s to 220L/s, and the surface finish of the pipe wall reaches Ra0.8μm, which significantly improves the pipeline drainage efficiency. At the same time, high-pressure water cleaning can be combined with CCTV pipeline detection technology to form a closed-loop operation and maintenance mode of “cleaning-detection-repair-verification”, reducing the single treatment cost by 40% and the construction period by 60%, realizing the transformation from “passive emergency rescue” to “active prevention”.​

In the field of sewer pipeline cleaning, high-pressure water technology also plays an irreplaceable role. Sewer pipelines in residential buildings, commercial buildings, schools and other places are prone to blockage due to a large amount of oil stains, food residues, hair and other debris contained in the daily discharged domestic sewage, which not only affects the normal life of residents, but also may breed bacteria, emit peculiar smell and endanger public health. High-pressure water cleaning equipment is flexible in volume and can be deployed through existing inspection wells or small operation pits, without large-scale excavation, effectively reducing the interference to the surrounding environment and residents’ lives. For small-diameter sewer pipelines (below DN300), micro nozzles and small crawling equipment can be matched to solve the cleaning blind areas that are difficult to reach by traditional methods; for severely blocked pipelines, high-pressure water jet can quickly break hardened deposits, and the dredging efficiency is 10-40 times higher than that of manual work, without damaging the inner wall of the pipeline, effectively extending the service life of the pipeline.​

The advantages of high-pressure water cleaning technology are not only reflected in high efficiency, environmental protection and non-destructive cleaning, but also have significant economic and social benefits. From the perspective of economic benefits, its cleaning cost is only 30%-50% of that of chemical cleaning, and it does not need to invest a lot of manpower. The dredging of a single section of pipeline (50-100m) only takes 30-60 minutes, which can greatly reduce the pipeline operation and maintenance cost; at the same time, regular cleaning can reduce the maintenance and replacement costs caused by pipeline blockage and corrosion, and extend the service life of the pipeline by 3-5 years. From the perspective of social benefits, high-pressure water cleaning can effectively improve the pipeline drainage capacity and reduce the road waterlogging time after rainstorms. For example, Xinjie Town, Yixing, Wuxi has shortened the road waterlogging time after rainstorms from 4 hours to 20 minutes through this technology, reducing the economic loss of enterprises due to waterlogging shutdown by 82%; at the same time, it reduces the pollution of sewage overflow to rivers, significantly reduces the COD concentration of surrounding rivers, improves the quality of urban water environment, and ensures the safety of residents’ living environment.​

With the continuous improvement of urban infrastructure construction, the importance of underground pipe network operation and maintenance has become increasingly prominent, and the application scenarios of high-pressure water cleaning technology are constantly expanding. In the future, combined with intelligent technologies such as PLC system control and pipeline robot collaborative operation, the automation and precision level of high-pressure water cleaning will be further improved, realizing intelligent operation and maintenance of pipeline cleaning. As a green, efficient and sustainable pipeline cleaning technology, high-pressure water cleaning will continue to empower the operation and maintenance of municipal and sewer pipelines, help build a safer, more environmentally friendly and more livable urban environment, and lay a solid foundation for underground infrastructure for high-quality urban development.