The 36-kilometer-long Hangzhou Bay Cross-sea Bridge requires steel pipe piles to be 71 to 88 meters long and 1.6 meters in ultra-large diameter. The pipe wall welding technology requires the use of variable wall thickness spiral welds that are not available in China. The technology and process are complex and the production is extremely difficult.
The latest anti-corrosion patented technology is used to ensure that the ultra-long steel pipe piles driven into the seabed will not corrode for a hundred years. Currently, this technology is at the leading level internationally.