... 3.Widely used in the drainage of railway,highway ,tunnel HDPE double-wall corrugated pipe using ... which consist of two layers, inner smooth wall and outer corrugation.Product Features:1.corrosion ... good abrasion resistance 4.longevityApplication Field :Widely used in the drainage of railway ,highway ,tunnel , ... homogeneous ,and the inner wall should be smooth , no burr. HDPE double-wall corrugated pipe