Specifications of International Thread Standards

Abbreviation Country Thread Angle
°
Description
ISO 60° International Organization for Standardization
UN USA 60° Unified National 8-, 12- and 16 pitch series
UNC USA 60° Unified National Coarse
UNEF USA 60° Unified National Extra Fine
UNF USA 60° Unified National Fine
UNJ USA 60° Unified National thread series with
external thread controlled root radius
UNJC USA 60° Unified National Coarse thread series
with external thread controlled root radius
UNJEF USA 60° Unified National Extra Fine thread series
with external thread controlled root radius
UNJF USA 60° Unified National Fine thread series
with external thread controlled root radius
UNJS USA 60° Unified National Special thread series
with external thread controlled root radius
UNR USA 60° Unified National thread series
with external thread controlled root radius
UNRC USA 60° Unified National Coarse thread series
with external thread controlled root radius
UNREF USA 60° Unified National Extra Fine thread series
with external thread controlled root radius
UNRF USA 60° Unified National Fine thread series
with external thread controlled root radius
UNRS USA 60° Unified National Special thread series
with external thread controlled root radius
UNS USA 60° Unified National Special
NPT USA 60° National Pipe Taper 1:16
NPTF USA 60° National Pipe Taper Fuel and Oil
Dryseal 1:16
NPTR USA 60° National Pipe Taper Railing Fittings
NPSC USA 60° National Pipe Straight Coupling
NPSF USA 60° National Pipe Straight Fuel
NPSG USA 60° National Pipe Straight Grease
NPSH USA 60° National Pipe Straight Hose
NPSI USA 60° National Pipe Straight Intermediate
NPSL USA 60° National Pipe Straight Loose
NPSM USA 60° National Pipe Straight Mechanical
BSW GB 55° British Standard Withworth Coarse
BSF GB 55° British Standard Fine
BSPP GB 55° British Strandard Pipe Parallel
BSPT GB 55° British Standard Pipe Taper
BA GB 47° British Standard Association
NC USA 60° National Coarse,
replaced with UNC in 1948
NF USA 60° National Fine,
replaced with UNF in 1948