N-12® Pipe (4" - 60")(100-1500mm)The hydraulic capabilities of theproduct were significantly improvedin 1987 when ADS introduced the firstHDPE drainage pipe to combine anannular corrugated exterior forstrength with a smooth interior wallfor maximum flow capacity. Namedfor its excellent Manning's "n" ratingof 0.012, N-12 pipe was designedspecifically for storm sewers, highways,airports, and other engineeredconstruction. Through extensive fieldand university testing, ADS engineerswere able to refine the corrugatedwall design for larger diameterswithout compromising the pipe'sexcellent strength-to-weight ratio. Itsperformance and economy have ledto rapid acceptance by contractorsand engineers, and official approvalby state and municipal agencies.