ANSI Thread Series Designations

Written by Matt Milbury. Posted in Thread Datasheets

DesignationsThread SeriesANSI Reference
ACME-C Acme Threads, centralizing ASME B1.5
ACME-G Acme threads, general purpose (see also Stub Acme) ASME B1.5
AMO American Standard microscope objective threads ASME B1.11
ANPT Aeronautical National Form taper pipe threads (2)  
BUTT Buttress threads, pull type ASME B1.9
PUSH-BUTT Buttress threads, push type ASME B1.9
F-PTF Dryseal fine taper pipe thread series ASME B1.20.3 (Appendix C)
M Metric screw threads - M profile with basic ISO 68 Profile ASME B1.13M, ASME B1.18M
MJ Metric screw threads - MJ profile with rounded root of radius (0.15011P to 0.18042P) ASME B1.21M
MJS Metric screw threads - MJ profile special series ASME B1.21M
  Class 5 interference fit external threads  
NC5HF For driving in hard ferrous material of hardness over 160 Bhn ASME B1.21M
NC5 CSF For driving in copper alloy and soft ferrous material of 160 Bhn or less ASME B1.21M
NC5 ONF For driving in other nonferrous material (Nonferrous materials other than copper alloys), any hardness ASME B1.21M
  Class 5 interference fit internal threads  
NC5 IF Entire ferrous material range ASME B1.21M
NC5 INF Entire nonferrous material range ASME B1.21M
NGO National gas outlet threads (1) ANSI/CGA V-1 (ASME B57.1)
NGS National gas straight threads ANSI/CGA V-1 (ASME B57.1)
NGT National gas taper threads (see also SGT) ANSI/CGA-V1 (ASME B57.1)
NH American Standard hose coupling threads of full form ASME B2.4 (ASME B1.20.7)
NHR American Standard hose coupling threads for garden hose applications ASME B2.4 (ASME B1.20.7)
NPSC American Standard Straight pipe threads in pipe couplings ASME B1.20.1
NPSF Dryseal American Standard fuel internal straight pipe threads ASME B1.20.3
NPSH American Standard straight hose coupling threads for joining to American Standard taper pipe threads ASME B2.4
NPSI Dryseal American Standard intermediate internal straight pipe threads ASME B1.20.3
NPSL American Standard straight pipe threads for loose-fitting mechanical joints with locknuts ASME B1.20.1
NPSM American Standard straight pipe threads for free-fitting mechanical joints with fixtures ASME B1.20.1
NPT American Standard taper pipe threads for general use ASME B1.20.1
NPTF Dryseal American Standard taper pipe threads ASME B1.20.3
PTF-SAE Short Dryseal SAE short taper pipe threads ASME B1.20.3
PTF-SPL Short Dryseal special short taper pipe threads ASME B1.20.3 (Appendix C)
S SO miniture screw threads .25 to 1.4mm, inclusive  
SGT Special gas taper threads ANSI/CGA V-1 (ASME B57.1)
SPL-PTF Dryseal special taper pipe threads ASME B1.20.3 (Appendix C)
Stub Acme United inch screw thread, constant-pitch series ASME B1.8
UN Unified inch screw thread, constant pitch series ASME B1.1
UNC Unified inch screw thread, coarse pitch series ASME B1.1
UNF Unified inch screw thread, fine pitch series ASME B1.1
UNEF Unified inch screw thread, extra-fine pitch series ASME B1.1
UNJ Unified inch screw thread, constant pitch series, with rounded root of radius 0.15011P to 0.18042P (3)  
UNJC Unified inch screw thread, coarse pitch series, with rounded root of radius 0.15011P to 0.18042P (3)  
UNJF Unified inch screw thread, fine pitch series, with rounded root of radius 0.15011P to 0.18042P (3)  
UNJEF Unified inch screw thread, extra-fine pitch series, with rounded root of radius 0.15011P to 0.18042P (3)  
UNJS Unified inch screw thread, special diameter, pitch or length, of engagement with rounded root radius of 0.15011P to 0.18042P (3)  
UNR Unified inch screw thread, constant pitch series, with rounded root of radius not less than 0.108P ASME B1.1
UNRC Unified inch screw thread, coarse pitch series, with rounded root of radius not less than 0.108P ASME B1.1
UNRF Unified inch screw thread, fine pitch series, with rounded root of radius not less than 0.108P ASME B1.1
UNREF Unified inch screw thread, extra-fine pitch series, with rounded root of radius not less than 0.108P ASME B1.1
UNM Unified miniature thread series ASME B1.10M
UNS Unified inch screw thread, special diameter pitch or length of engagement ASME B1.1

Notes:

  • (1) All threads, except NGO, are right hand, unless otherwise designated. For NGO threads, designations RH or LH are required.
  • (2) As published in SAE A571051
  • (3) As published in Military Specification MIL-S8879, ISO 3161 and ASME B1.15.