タイトルまたは説明

Copper valve, which is a copper cast valve, belongs to industrial parts. It was the first to develop the manufacturing process in China, Ningbo, Zhejiang, the first in China. In the early ***0s, Ningbo, Zhejiang, took the lead in developing the manufacturing process, which changed the history of long term use of cast iron valves in China. In the manufacturing process, the sand casting process was first adopted, and it was changed into the forging process at the beginning of *0s. China has developed into a world copper valve manufacturing center in the early twenty-first Century.