... used in the drainage of railway,highway ,tunnel HDPE double-wall corrugated pipe using HDPE as main material, and adds various plastic ... , a pipe formed which consist of two layers, inner smooth wall and outer corrugation.Product Features:1.corrosion resistance 2.light ... ×1mm≤30×3mm surface should be homogeneous ,and the inner wall should be smooth , no burr. HDPE double-wall corrugated pipe