American National Pipe Thread Code
Code Description
PTF SAE short taper pipe thread
NPTF American National taper pipe thread for Dryseal pressure-tight joints
NPSM American National straight pipe thread for mechanical joints
NPSI American National straight intermediate pipe thread
BSP British Standard pipe thread

AS, AS2 AS3 fittings conform to SAE AS35411
AS1 fittings conform to Boeing BPS-F-219