N-12 corrugated dual-wall pipe was introduced in 1987. Today's N-12 ST IB pipe (per ASTM F2648) is an engineered compound of virgin and recycled high density polyethylene resins to provide impressive material properties. The performance you've come to expect from N-12, with the added benefit of helping to promote responsible use of resources. Available in diameters from 4'' to 60'' (100 to 1500 mm), N-12 pipe is replacing reinforced concrete pipe as a preferred product for storm water applications. ADS N-12 ST IB pipe (per ASTM F2648) contains a superior built-in bell-and spigot joint. The joints are sealed by high-quality, factory-installed rubber gaskets that meet all the requirements of ASTM F477. A polyethylene bell minimizes joint distortion. The chipping and cracking that is common to concrete bells, is eliminated.