Taper Pipe Taps For Cast Iron • Taper pipe taps for Cast Iron feature specific geometry for tapping materials that porduce small or powdery chips. • Recommended for cast iron, cast brass, and other brass materials and non-metals that produce small or powdery chips. • NPT threads require the use thread sealant to ensure tight seal. • Steam Oxide Over Nitride increases wear resistance, reduces friction, reduces galling and chip welding, improves chip flow and increases tap lubricant retention.