... Widely used in the drainage of railway,highway ,tunnel HDPE double-wall corrugated pipe using HDPE as main material, and adds various plastic additives,then ... ,highway ,tunnel , waste landfill, green belts ,sports ground and slopes with high water content, etc.1 Municipal engineering rainwater, sewage discharges ... ,and the inner wall should be smooth , no burr. HDPE double-wall corrugated pipe