Triple bonded polyethylene for exceptional pipe stiffness. With smooth inner and outer walls and a corrugated structural core, Meeting ASTM F810, Smoothwall is very popular for sanitary leach field use because of its low cost, large perforations, and high beam strength when compared to singlewall perforated polyethylene pipe. Beam strength is a measure of the stiffness of a pipe in the longitudinal direction. The pipe provides for safe, easy, efficient installations without breaking, splitting or cracking.