"DESCRIPTION FEATURES: NPT (National Pipe Tapered) NPT is a US standard for tapered threads used to join pipes and fittings. ANSI/ASME standard B1.20.1 covers threads of 60° form with flat crests and roots. The taper on NPT threads allows them to form a seal when torqued as the flanks of the threads compress against each other. However a clearance remains between the crests and roots of the threads, resulting in a leakage around this spiral. This means that NPT fittings must be made leak free with the aid of thread seal tape or a thread sealant compound. For each 12″ increase in distance from the end, the diameter increases by 3/4″. Bottoming Taps have a lead of two threads and are used to ensure minimum thread run-out when tapping to the bottom of a blind hole. Bottoming Taps are typically preceded by the use of a Taper or Intermediate Tap. REVIEWS"