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National Pipe Taper Fuel

This thread type is the most commonly used tapered pipe thread connection found on equipment made in North America. Additional sealing aids such as Teflon® tape are used with these threads. This connection is often used on fluid power systems, although it is not recommended by the National Fluid Power Association for use in hydraulic applications.

NPTF Thread Specifications
Thread Size	Nominal Size (in)	Number of Threads per Inch	Male Thread O.D. (in)
2	1/8	27	13/32
4	1/4	18	35/64
6	3/8	18	43/64
8	1/2	14	27/32
12	3/4	14	1-1/16
16	1	11.5	1-5/16
20	1-1/4	11.5	1-21/32
24	1-1/2	11.5	1-29/32
32	2	11.5	2-3/8
40	2-1/2	8	2-7/8
48	3	8	3-1/2
64	4	8	4-1/2

Thread conforms to ANSI B1.20.3

Physically interchangeable with NPT but has modified threads for better pressure tight sealing

Tapered thread profile seals by metal to metal interference fit, usually requires sealing compound for pressure tight connections

Pitch and diameter are measured in inches

Taper angle is 0.75" per foot or 1° 47'

Thread angle is 60°

Pipe Fitting Assembly

1: Inspect port components to ensure that male and female threads are free of nicks, burrs, dirt, etc.

2: Apply sealant/lubricant to male pipe threads. Pre-applied Vibraseal is preferred over other sealants. With any sealant, the first few threads should be left uncovered to avoid system contamination (see Fig. 1). If Teflon® tape is used, it should be wrapped 1-1/2 turns in a clockwise direction when viewed from the end.

3. Screw Fitting into female pipe port to finger tight position.

4. Wrench tighten fitting to the appropriate TFFT shown in the chart to the right, making sure the tube end of the shaped fitting is aligned to receive incoming tube or hose assembly.

Pipe Thread Size	Turns From Finger Tight
2	2.0 - 3.0
4	2.0 - 3.0
6	1.5 - 3.0
8	2.0 - 3.0
12	2.0 - 3.0
16	1.5 - 2.5
20	1.5 - 2.5
24	1.5 - 2.5
32	1.5 - 2.5