Similar to other corrugated metal pipes, helical corrugated metal pipe has also the corrugation shape. Corrugations add the structural strength and stiffness to culverts. More over, helical corrugated metal pipe has the special corrugation - annular pattern corrugations, which not only make the culverts more strong and stiff, but also reduce the roughness of flow through the pipe. Helical corrugated metal pipe specifications Code DN (mm) Thickness (mm) Corrugation (mm) Galvanization (g/m2) Using life (years) HCMP-1 300-400 1.6-2.0 68 脳 13 鈮�300 鈮�100 HCMP-2 500-800 1.6-2.8 68 脳 13 鈮�300 鈮�100 HCMP-3 700-1200 1.6-4.2 68 脳 13 鈮�300 鈮�100 HCMP-4 1400-1600 2.0-4.2 68 脳 13, 75 脳 25, 125 脳 25 鈮�300 鈮�100 HCMP-5 1700-2400 2.8-4.2 68 脳 13, 75 脳 25, 125 脳 25 鈮�300 鈮�100 HCMP-6 2500-3600 3.0-4.2 75 脳 2,5 125 脳 25 鈮�300 鈮�100 As a professional company devoted to providing our customers optimal corrugated steel pipe solutions, we accept customization on pipe diameter and wall thickness, either galvanized and asphalt coating or polymer coated steel is OK.