16 catalogued sizes, dimensioned to ASME B1.20.1. Pick any row and the technical drawing redraws to it.
NPT Pipe Thread Fittings to ASME B1.20.1 are catalogued in dia 7.94-168.28 mm, with pitch 0.94-3.18 mm. 16 sizes are held in the table below, and the technical drawing redraws to whichever row you select.
Standard
ASME B1.20.1
Dia
7.94-168.28 mm
Pitch
0.94-3.18 mm
Catalogued sizes
16
Dimensions are nominal values from the governing standard. Confirm the tolerance class for your application before ordering.
Process & plant pipingTapped connections on equipment and manifolds.
Pneumatics & automationAir lines, cylinders and valve manifolds.
Typical applications
joining and sealing a fluid or air line
adapting between thread forms on a manifold
Service conditions to specify against
Marine and coastal
Available in A4 (316) stainless for chloride exposure — coastal structures, pool halls, water treatment and deck hardware, where A2 will eventually pit.
Sealed joints
Used where the fixing has to keep water or air out as well as hold — the elastomer, not the fastener, decides service life.
Customize the parameters below — every spec field is editable, and the drawing redraws to match the values you choose. Changing the size will snap the other fields to that size's standard values; you can then override any individual value.
Dimensioned line drawing of 1/16 NPT NPT Pipe Thread Fittings to ASME B1.20.1. Side view and top view, drawn to the dimensions in the table below and redrawn for any size selected.
Nominal size (in)
1/16
Major diameter (mm)
7.938
Pitch (mm)
0.941
Threads per inch (TPI)
27
Taper
1:16
Notes
Tapered pipe thread, self-sealing
Sends the selected values to the quote form below.
Request a Quotation for NPT Pipe Thread Fittings
The form below follows the current technical drawing configuration. Change the drawing values above and the request details update automatically.
Dimensions & Specifications (ASME B1.20.1)
Every row below is a starting point for the customizer above — pick any size and the drawing will redraw to that row.
Size
Nominal size (in)
Major diameter (mm)
Pitch (mm)
Threads per inch (TPI)
Taper
Reference standard
Notes
1/16 NPT
1/16
7.938
0.941
27
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
1/8 NPT
1/8
10.287
0.941
27
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
1/4 NPT
1/4
13.716
1.411
18
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
3/8 NPT
3/8
17.145
1.411
18
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
1/2 NPT
1/2
21.336
1.814
14
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
3/4 NPT
3/4
26.67
1.814
14
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
1 NPT
1
33.401
2.209
11.5
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
1-1/4 NPT
1-1/4
42.164
2.209
11.5
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
1-1/2 NPT
1-1/2
48.26
2.209
11.5
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
2 NPT
2
60.325
2.209
11.5
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
2-1/2 NPT
2-1/2
73.025
3.175
8
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
3 NPT
3
88.9
3.175
8
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
3-1/2 NPT
3-1/2
101.6
3.175
8
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
4 NPT
4
114.3
3.175
8
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
5 NPT
5
141.3
3.175
8
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
6 NPT
6
168.275
3.175
8
1:16
ASME B1.20.1
Tapered pipe thread, self-sealing
Manufactured to ASME B1.20.1, NPT Pipe Thread Fittings are pipe & pneumatic fittings supplied by Engineering Hardware. The dimensional data, materials and selection notes are summarized here.
What Are NPT Pipe Thread Fittings?
NPT Pipe Thread Fittings are pipe & pneumatic fittings defined by ASME B1.20.1. They are selected by screw size and the dimensional characteristics shown below, and are available in a range of materials and finishes to suit the application and environment.
Materials & Finishes
Common materials include carbon steel (typically zinc plated or hot-dip galvanized), hardened or case-hardened steel where wear matters, and stainless steel A2 (304) or A4 (316) for corrosion resistance. Specify the material, hardness where relevant, and the surface finish appropriate to your application and environment.
Specification Guides
Each size, material and standard of NPT Pipe Thread Fittings has its own reference page with the figures for that one configuration.
NPT Pipe Thread Fittings are supplied to order. Pricing starts from approximately US$0.20 per piece for standard sizes in carbon steel; final pricing depends on size, material, finish and order quantity (MOQ applies). Submit your exact configuration with the quote form above.
Custom manufacturing · Made to drawing
Need a NPT pipe thread fittings outside the standard range?
Dimensions, material, finish and form are specified from the drawing — a pipe & pneumatic fitting outside the standard range is a variation on existing tooling rather than a new design.
Minimum order from 2,000 pieces; samples within 7 days of drawing approval.
This part is cold-formed, threaded, heat-treated and finished in-house. The stages below are where its class and finish are actually decided.
01
Cold heading
Wire rod is drawn to size and cold-formed into blanks. Forming rather than cutting keeps the grain flow continuous around the head, which is where a bolt is most likely to fail.
Head dimensions and under-head radius checked at set-up and per shift.
02
Thread rolling
Threads are rolled between hardened dies rather than cut. Rolled threads are stronger in fatigue than cut threads and hold pitch and flank angle far more consistently across a batch.
Go / no-go ring gauges to ISO 965 tolerance class 6g.
03
Heat treatment
Quench-and-temper brings carbon and alloy steel to the property class ordered — 8.8, 10.9 or 12.9 — with the furnace charge tracked so a finished lot can be traced back to it.
Core hardness and tensile tested per lot to ISO 898-1.
04
Surface treatment
Zinc, zinc-nickel, hot-dip galvanizing, black oxide, phosphate and Dacromet, selected against the service environment rather than against the price list.
Coating thickness and neutral salt spray hours to ISO 9227.
Third-party video, selected automatically for this topic. It is not produced by Engineering Hardware and is not a specification source — use the tables on this page for dimensional data.
Frequently Asked Questions
What is the controlling standard for NPT Pipe Thread Fittings?
NPT Pipe Thread Fittings are manufactured to ASME B1.20.1. The dimensional values on this page follow that standard.
Which sizes of NPT Pipe Thread Fittings does Engineering Hardware supply?
The table on this page lists 16 sizes for NPT Pipe Thread Fittings, ranging from 1/16 NPT to 6 NPT. Sizes outside the table can be quoted on request.
In which materials are NPT Pipe Thread Fittings supplied?
NPT Pipe Thread Fittings are supplied in brass, carbon steel and stainless, with finishes including zinc plating, hot-dip galvanizing and black oxide. Choose material and finish to suit the load and the service environment for NPT Pipe Thread Fittings.
How do I request a quotation?
Use the parametric drawing on this page to set the exact configuration (size, material, finish) and click "Request this configuration" — a specialist from Engineering Hardware will respond within one business day.
Need a fastener quote or a spec sheet?Message our engineers on WhatsApp — send a drawing or DIN number and get pricing back fast.Start WhatsApp Chat →
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