[NMR Pipe Protector Withdrawal Investigation] Yaesu Entrance Hall Rust Prevention Effect Verification

A galvanized steel cooling pipe with a durability of 20 years demonstrated rust prevention after 58 years of removal.

The air conditioning cooling water piping at the Yaesu Exit Hall was made of galvanized steel pipes and had significant red rust corrosion. After installing NMR pipe protectors at three locations, including the cooling water piping, the water inside the pipes became clear within a week, and the total iron content due to red rust decreased from 11 mg/L before installation to less than 0.1 mg/L, approximately one-hundredth of the original level. In December 2023, 58 years after construction, when the piping for the air conditioning cooling water was removed, there was no visible red rust inside the pipes, and there was almost no thinning of the material. A thin layer of soft calcium scale that could be removed with a finger was formed on the inside, and the general contractor representatives present confirmed that a black rust layer covered the entire inner surface of the piping beneath it. Measurements of the pipe wall thickness at four locations with calipers showed all were 5.9 mm, which is nearly equivalent to a new 200A galvanized steel pipe (JIS standard 5.8 mm). The general contractor representatives responsible for the cutting and the facility personnel of the building were very surprised by the results.

Piping Materials