SAE UNC, UNF, UNS, UNJ, UNEF, NPT NPTF, NPSM full form thread

Date:Apr 11, 2020

United States Standard thread is defined by SAE international, it is the Society of Automotive Engineers. globally active professional association and standards developing organization for engineering professionals in various industries such as aerospace, automotive, and commercial vehicles.



Unified Thread Standard (UTS), is the dominant thread standard used in the United States and Canada. It is defined in ANSI/ASME B1.1 Unified Inch Screw Threads, (UN and UNR Thread Form). In some cases products are still made according to the old American National Standard Series, which has slightly different specifications, and has been technically obsolete since 1949. The old national standard is compatible with the newer unified standard, but is long out of date. This unified standard includes:

UNC is Unified Coarse thread , the successor to the obsolete National Coarse (NC) thread.

UNF is Unified Fine thread, the successor to the obsolete National Fine (NF) thread.

UNEF is Unified Extra Fine thread

UNS is Unified Special thread

UNJ is Aerospace inch threads – ISO 3161

NPT National pipe thread is used (in the U.S.) for plumbing of water and gas pipes, and threaded electrical conduit. NPT is defined by ANSI/ASME standard B1.20.1, American National Standard Taper Pipe Thread.

NPTR is National pipe taper railing thread, American National Standard Taper Pipe Thread for Railing Joints

NPTF is National Pipe Thread Fuel according to ANSI/ASME B1.20.1-1983, Dryseal USA (American) Standard Taper Pipe Thread.

NPS is National pipe straight, American National Standard Straight Pipe Thread is for rigidity; sealable only with sealant; sometimes male straight enclosed by female tapered for low-pressure sealing.

NPSC is National pipe straight–coupling, American National Standard Straight Pipe Thread for Couplings For general couplings.

NPSF is National pipe straight–fuel, Dryseal USA (American) Standard Fuel Internal Straight Pipe Thread for Internal only, straight.

NPSH is National pipe straight–hose, American National Standard Straight Pipe Thread for Hose Couplings for hose coupling.

NPSI  is National pipe straight–intermediate, Dryseal USA (American) Standard Intermediate Internal Straight Pipe Thread for internal only, straight, Similar to NPSF but slightly larger.

NPSL is National pipe straight–locknut , American National Standard Straight Pipe Thread for Loose-fitting Mechanical Joints with Locknuts.

NPSM is National Pipe Straight Mechanical ANSI/ASME B1.20.1-1983, American National Standard Straight Pipe Thread for Free-fitting Mechanical Joints. ]

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