... in the drainage of railway,highway ,tunnel HDPE double-wall corrugated pipe using HDPE as main material, and adds various plastic additives,then ... The water worksPerformance Parameter: item technical parameter ring stiffness(KN/m2)≥6.3flattening testGive pressure in vertical and diameter deformation at ... homogeneous ,and the inner wall should be smooth , no burr. HDPE double-wall corrugated pipe