NPT is available in tapered helicoil type inserts but we do not recommend wire thread helicoil type inserts as a good repair for tapered threads because they are hard to fit properly and the taper tends to make them easy to dislodge. TECHNICAL DATA IS AVAILABLE ON SPECIAL REQUEST but the better repair for NPT is a Time-Sert - [click for details].
NPT stands for National Pipe [Tapered] and is the US type of pipe thread used in applications where BSPT would be used in Europe. It is the designation for general usage tapered connections of US origin and there are many other NPT designations such as NPTF [F stands for fuel]. These other NPT variants are generally made to special tolerances.
There are also NP parallel threads and the most common one is known as NPSM which stands for National Pipe Straight Mechanical.