23. Symbol for Standard Threads Intro America SP Thread symbol Kinds of thread Related Standard UN Unified inch screw threads ANSI B 1.1 UNC/UNRC Unified coarse thread series ANSI B 1.1 UNF/UNRF Unified fine thread series ANSI B 1.1 SL UNEF/UNREF Unified extra-fine thread series ANSI B 1.1 4UN/4UNR Unified constant-pitch series with 4-threads ANSI B 1.1 6UN/6UNR Unified constant-pitch series with 6-threads ANSI B 1.1 8UN/8UNR Unified constant-pitch series with 8-threads ANSI B 1.1 PO 12UN/12UNR Unified constant-pitch series with 12-threads ANSI B 1.1 16UN/16UNR Unified constant-pitch series with 16-threads ANSI B 1.1 20UN/20UNR Unified constant-pitch series with 20-threads ANSI B 1.1 28UN/28UNR Unified constant-pitch series with 28-threads ANSI B 1.1 ST 32UN/32UNR Unified constant-pitch series with 32-threads ANSI B 1.1 UNS/UNRS Unified threads of special diameters, pitches and lengths of engagement ANSI B 1.1 NR American National thread with a 0.108p to 0.144p controlled root radius MIL-B-7838 Acme Acme screw threads ANSI B 1.5 ROLL Stub-Acme Stub Acme screw threads ANSI B 1.8 Butt Buttress inch screw threads ANSI B 1.9 UNM Unified miniature thread series ANSI B 1.10 NC5 Class 5 interference-fit thread ANSI B 1.12 CARBIDE NPT American Standard taper pipe threads tor general use ANSI/ASME B 1.20.1 NPTR American Standard taper pipe threads tor railing joints ANSI/ASME B 1.20.1 NPSC American Standard straight pipe thread in pipe couplings ANSI/ASME B 1.20.1 NPSL American standard straight pipe threads for loose-fitting mechanical joints with locknuts ANSI/ASME B 1.20.1 NPSM American Standard straight pipe threads for free-fitting mechanical joints for fixture ANSI/ASME B 1.20.1 LONG NPSH American Standard straight pipe threads tor loose-fitting mechanical joints for hose couplings ANSI/ASME B 1.20.1 NPTF Dryseal American Standard taper pipe threads ANSI B 1.20.3, 1.20.4 F-PTF Dryseal fine taper pipe thread series ANSI B 1.20.3, 1.20.4 HAND PTF-SAE SHORT Dryseal SAE short taper pipe threads ANSI B 1.20.3, 1.20.4 TAPS PTF-SPL SHORT Dryseal special short taper pipe threads ANSI B 1.20.3, 1.20.4 PTF-SPL EXTRA SHORT Dryseal special extra short taper pipe threads ANSI B 1.20.3, 1.20.4 SPL-PTF Dryseal special taper pipe threads ANSI B 1.20.3, 1.20.4 NPSI Dryseal American Standard intermediate internal straight pipe threads ANSI B 1.20.3, 1.20.4 EG (STI) NPSF Dryseal American Standard fuel internal straight pipe threads ANSI B 1.20.3, 1.20.4 ANPT Aeronautical National Form taper pipe threads MIL-P-7150 NGO National gas outlet threads ANSI B 57.1 SPECIAL NGS National gas straight threads ANSI B 57.1 THREADS, NGT National gas taper threads ANSI B 57.1 GAUGES SGT Special gas taper threads ANSI B 57.1 NH Hose coupling and firehose coupling threads USAS B 2.4 NHR Hose coupling and firehose coupling threads USAS B 2.4 THREAD NPSH Hose coupling and firehose coupling threads USAS B 2.4 MILLS AMO American standard microscope objective threads ANSI B 1.11 DIES CENTER DRILLS Technical info 714