3" NPT Thread Specs
Standard: ASME B1.20.1 (NPT)
Technical parameters and design data for the 3" NPT pipe thread.
Established under standard ASME B1.20.1, this thread uses a pitch of 0.125 inches and has 8 threads per inch.
Often used in fluid, hydraulic, or pneumatic systems, NPT/BSP threads require suitable thread sealants to assure leak-tight performance.
Dimensional Specifications
Size Designation
3" NPT
Nominal Diameter
3.5 in(88.9 mm)
Major Diameter
3.9313 in(99.86 mm)
TPI (Threads per Inch)
8
Pitch
0.125 in
Pitch Diameter
3.8501 in(97.79 mm)
Minor Diameter
3.796 in(96.42 mm)
Tap Drill size
3-1/4 in
Quick Unit Converter
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Frequently Asked Questions
What is the tap drill size for 3" NPT pipe thread?
The recommended tap drill size for a 3" NPT pipe thread is 3-1/4 inches.
What is the major diameter of a 3" NPT pipe thread?
For a standard 3" NPT pipe thread, the major diameter at the pipe reference plane is 3.9313 inches (approx. 99.86 mm).