# 2012 Barcelona
Corrugated high density polyethylene (HDPE) pipe has been used in various drainage applications in the United States for nearly 50 years. First developed in smaller diameters primarily for agricultural applications, the product quickly found its way into the highway industry as an edge drain to increase pavement performance. By the 1980s larger diameter pipes were being manufactured for culverts, storm sewers, and detention systems. Though many of the pipes produced in the 1980s are still functioning well today, the industry and products have continued to evolve to meet the increasing service life requirements of many state departments of transportation. While most of the manufacturing methods are still the same, the materials have significantly evolved over time. Of particular interest is the stress crack resistance properties of corrugated HDPE pipe materials, which have seen nearly a 10-fold increase over the past 30 years. Recent testing performed on early pipe materials shows Notched Constant Ligament Stress (NCLS) test results of around 10 hours, while many current materials test over 100 hours. This paper compares some of the early materials used to manufacture corrugated HDPE pipe with current materials, particularly focusing on stress crack resistance. It also details some of the standards and drivers in the corrugated HDPE pipe industry over the U.S. over the past 30 years that have led to this significant increase in performance properties of the product.