... between double surfaces. With its unique wall structure design, such pipe has advantages of strong ring stiffness, light weight, high ... material pipes.According to different ring stiffness grades,HDPE double wall corrugated pipe falls into S1(ring stiffness≥4KN/m2)and ... ):200mm, 225mm, 300mm, 400mm, 500mm, 600mm, 700mm ,800mm and 1000mm. Advantages:Non-toxic: no heavy metal additives, would not be ...