... railway,highway ,tunnel HDPE double-wall corrugated pipe using HDPE as main material, and adds various plastic additives,then by twin-screw ... , waste landfill, green belts ,sports ground and slopes with high water content, etc.1 Municipal engineering rainwater, sewage discharges;2 ... ×3mm surface should be homogeneous ,and the inner wall should be smooth , no burr. HDPE double-wall corrugated pipe