... :Structure 4)Certification:ISO9001:20001)Product Name:ASTM A53 Hot-dip Galvanized steel pipe2)Place of Origin:Nantong China( ... the following production steps:a. Round preparation, b. Heating, c. Hot perforation, d. Cutting head, e. Pickling, f. Grinding, g. ... gas pipes, water transport and water supply projects; building, central air-conditioning pipe, fence, threading pipe, rolling doors, metal frame, ...