Pipe anti-corrosion: Yokohama City Waterworks Bureau conducts effectiveness verification of NMR pipe protectors (1)

The Yokohama City Waterworks Bureau has verified the effectiveness of the NMR pipe protector in preventing red rust and reducing chlorine levels for disinfection in the water supply pipes at the Tsurumi public housing.

At the Yokohama City Waterworks Bureau, a demonstration test was conducted at the 20-year-old Tsurumi water reservoir's attached public housing to prevent red rust from occurring in the water supply pipes, thereby solving the problem of reduced chlorine concentration in the water due to red rust. The test was carried out using the water supply pipe in the vacant bathroom of room 102. The piping materials used included polyethylene-lined steel pipes in the shared areas and resin pipes in the exclusive areas, where red rust was found to be occurring at the pipe joint sections. Before the installation of the NMR pipe protector, the iron concentration in the stagnant water at the bathtub water supply faucet during nighttime was 0.27 mg/L, with a residual chlorine level of 0.11 ppm at that time. Additionally, over the two weeks prior to installation (with water flowing for 3 hours a day), the amount of red rust accumulated on the faucet filter was 13 mg/L, indicating that corrosion due to red rust at the pipe joint sections was significantly advanced.

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Subsequently, an NM-R pipe protector for preventing red rust in the piping was installed in the entire water supply piping (50A) of the Tsurumi public housing. One week after the installation of the NM-R pipe protector, the iron content in the overnight stagnant water from the bathtub water supply faucet, sampled under the same conditions as before installation, decreased to 0.15 mg/L, while the residual chlorine increased to 0.56 ppm, five times higher than before installation. This demonstrated that the NM-R pipe protector completely halted new red rust deterioration, and the surface of the existing red rust turned into passive black rust, stopping the reduction of chlorine. Four weeks after installation, the iron content in the overnight stagnant water from the same bathtub water supply faucet was 0.14 mg/L, proving that the rust prevention effect of the NM-R pipe protector was sustained, with a residual chlorine level of 0.52 ppm indicating a high concentration of residual chlorine. Additionally, the amount of red rust attached to the filter before installation was 13 mg/L, which drastically reduced to 4.8 mg/L under the same conditions four weeks later, demonstrating the rust prevention effect of the NM-R pipe protector and its ability to reduce the outflow of red rust by converting it to black rust.