... :a. Round preparation, b. Heating, c. Hot perforation, d. Cutting head, e. Pickling, f. Grinding, g.Lubrication, h. Cold rolling, i. Degreasing ... , j. Solution heat treatment, k. Straightening, l. Cutting, m. Pickling, n. Inspection 12.Application:Water pipes, fire control, gas pipes, air pipes ...