NPT Pipe Thread Dimensions | NPT Thread Size | NPT Pipe Thread Size
When working with pipes and fittings, having accurate information about thread sizes and dimensions is crucial. The National Pipe Taper (NPT) chart is a key reference for professionals in plumbing, manufacturing, and engineering. This guide provides an overview of the NPT chart, its significance, and its applications, along with a detailed table for quick reference.
NPT Pipe Thread Dimensions and Chart
| Outside Diameter D | Nominal Pipe Size | Threads per Inch (Pitch) | Thread Pitch Length, P | Pitch Diameter at External Thread Start E0 | Hand Tight Thread Engagement Length, L1 | Diameter E1 | Maximum Thread Engagement L2 | Diameter E2 |
|---|---|---|---|---|---|---|---|---|
| 0.3125 | 1/16 | 27 | 0.03704 | 0.27118 | 0.160 | 0.28118 | 0.2611 | 0.2875 |
| 0.405 | 1/8 | 27 | 0.03704 | 0.36351 | 0.1615 | 0.3736 | 0.2639 | 0.3800 |
| 0.540 | 1/4 | 18 | 0.05556 | 0.47739 | 0.2278 | 0.49163 | 0.4018 | 0.5025 |
| 0.675 | 3/8 | 18 | 0.05556 | 0.61201 | 0.240 | 0.62701 | 0.4078 | 0.6375 |
| 0.840 | 1/2 | 14 | 0.07143 | 0.75843 | 0.320 | 0.77843 | 0.5337 | 0.79179 |
| 1.050 | 3/4 | 14 | 0.07143 | 0.96768 | 0.339 | 0.98887 | 0.5457 | 1.00179 |
| 1.315 | 1 | 11.5 | 0.08696 | 1.2163 | 0.400 | 1.23863 | 0.628 | 1.2563 |
| 1.660 | 1 1/4 | 11.5 | 0.08696 | 1.55713 | 0.420 | 1.58338 | 0.7068 | 1.5013 |
| 1.900 | 1 1/2 | 11.5 | 0.08696 | 1.79609 | 0.420 | 1.82234 | 0.7235 | 1.413 |
| 2.375 | 2 | 11.5 | 0.08696 | 2.26902 | 0.436 | 2.29627 | 0.7565 | 2.3163 |
NPT Pipe Thread Size
NPT Chart Size Guide
| Outside Diameter | Nominal Pipe Size | Threads Per Inch (Pitch) | Thread Pitch Length | Pitch Diameter at External Thread Start | Hand Tight Thread Engagement Length | Diameter | Maximum Thread Engagement | Diameter |
|---|---|---|---|---|---|---|---|---|
| 0.3125 | 1/16 | 27 | 0.03704 | 0.27118 | 0.160 | 0.28118 | 0.2611 | 0.2875 |
| 0.405 | 1/8 | 27 | 0.03704 | 0.36351 | 0.1615 | 0.3736 | 0.2639 | 0.3800 |
| 0.540 | 1/4 | 18 | 0.05556 | 0.47739 | 0.2278 | 0.49163 | 0.4018 | 0.5025 |
| 0.675 | 3/8 | 18 | 0.05556 | 0.61201 | 0.240 | 0.62701 | 0.4018 | 0.6400 |
| 0.840 | 1/2 | 14 | 0.07143 | 0.75843 | 0.320 | 0.77843 | 0.5337 | 0.79179 |
| 1.050 | 3/4 | 14 | 0.07143 | 0.96768 | 0.339 | 0.98887 | 0.5457 | 1.00179 |
| 1.315 | 1 | 11 1/2 | 0.08696 | 1.2163 | 0.400 | 1.23863 | 0.6828 | 1.25617 |
| 1.660 | 1 1/4 | 11 1/2 | 0.08696 | 1.55713 | 0.420 | 1.58338 | 0.7068 | 1.61117 |
| 1.900 | 1 1/2 | 11 1/2 | 0.08696 | 1.78209 | 0.420 | 1.80729 | 0.7565 | 1.86134 |
| 2.375 | 2 | 11 1/2 | 0.08696 | 2.26902 | 0.450 | 2.29627 | 0.7565 | 2.31345 |
| 2.875 | 2 1/2 | 8 | 0.125 | 2.69502 | 0.640 | 2.73102 | 1.125 | 2.850 |
| 3.500 | 3 | 8 | 0.125 | 3.319 | 0.640 | 3.375 | 1.125 | 3.500 |
| 4.000 | 4 | 8 | 0.125 | 3.800 | 0.640 | 3.875 | 1.125 | 4.000 |
| 4.500 | 5 | 8 | 0.125 | 4.319 | 0.640 | 4.375 | 1.125 | 4.500 |
| 5.563 | 6 | 8 | 0.125 | 5.363 | 0.640 | 5.425 | 1.125 | 5.563 |
| 6.625 | 7 | 8 | 0.125 | 6.363 | 0.640 | 6.425 | 1.125 | 6.625 |
| 8.000 | 8 | 8 | 0.125 | 7.900 | 0.640 | 8.000 | 1.125 | 8.000 |
| 9.000 | 9 | 8 | 0.125 | 8.900 | 0.640 | 9.000 | 1.125 | 9.125 |
| 10.000 | 10 | 8 | 0.125 | 9.900 | 0.640 | 10.000 | 1.125 | 10.125 |
| 11.000 | 11 | 8 | 0.125 | 10.900 | 0.640 | 11.000 | 1.125 | 11.125 |
| 12.000 | 12 | 8 | 0.125 | 11.900 | 0.640 | 12.000 | 1.125 | 12.125 |
| 13.000 | 13 | 8 | 0.125 | 12.900 | 0.640 | 13.000 | 1.125 | 13.125 |
| 14.000 | 14 | 8 | 0.125 | 13.900 | 0.640 | 14.000 | 1.125 | 14.125 |
| 15.000 | 15 | 8 | 0.125 | 14.900 | 0.640 | 15.000 | 1.125 | 15.125 |
| 16.000 | 16 | 8 | 0.125 | 15.900 | 0.640 | 16.000 | 1.125 | 16.125 |
| 17.000 | 17 | 8 | 0.125 | 16.900 | 0.640 | 17.000 | 1.125 | 17.125 |
| 18.000 | 18 | 8 | 0.125 | 17.900 | 0.640 | 18.000 | 1.125 | 18.125 |
| 19.000 | 19 | 8 | 0.125 | 18.900 | 0.640 | 19.000 | 1.125 | 19.125 |
| 20.000 | 20 | 8 | 0.125 | 19.900 | 0.640 | 20.000 | 1.125 | 20.125 |
| 21.000 | 21 | 8 | 0.125 | 20.900 | 0.640 | 21.000 | 1.125 | 21.125 |
| 22.000 | 22 | 8 | 0.125 | 21.900 | 0.640 | 22.000 | 1.125 | 22.125 |
| 23.000 | 23 | 8 | 0.125 | 22.900 | 0.640 | 23.000 | 1.125 | 23.125 |
| 24.000 | 24 | 8 | 0.125 | 23.900 | 0.640 | 24.000 | 1.125 | 24.125 |
| 25.000 | 25 | 8 | 0.125 | 24.900 | 0.640 | 25.000 | 1.125 | 25.125 |
| 26.000 | 26 | 8 | 0.125 | 25.900 | 0.640 | 26.000 | 1.125 | 26.125 |
| 27.000 | 27 | 8 | 0.125 | 26.900 | 0.640 | 27.000 | 1.125 | 27.125 |
| 28.000 | 28 | 8 | 0.125 | 27.900 | 0.640 | 28.000 | 1.125 | 28.125 |
| 29.000 | 29 | 8 | 0.125 | 28.900 | 0.640 | 29.000 | 1.125 | 29.125 |
| 30.000 | 30 | 8 | 0.125 | 29.900 | 0.640 | 30.000 | 1.125 | 30.125 |
| 31.000 | 31 | 8 | 0.125 | 30.900 | 0.640 | 31.000 | 1.125 | 31.125 |
| 32.000 | 32 | 8 | 0.125 | 31.900 | 0.640 | 32.000 | 1.125 | 32.125 |
| 33.000 | 33 | 8 | 0.125 | 32.900 | 0.640 | 33.000 | 1.125 | 33.125 |
| 34.000 | 34 | 8 | 0.125 | 33.900 | 0.640 | 34.000 | 1.125 | 34.125 |
| 35.000 | 35 | 8 | 0.125 | 34.900 | 0.640 | 35.000 | 1.125 | 35.125 |
| 36.000 | 36 | 8 | 0.125 | 35.900 | 0.640 | 36.000 | 1.125 | 36.125 |
| 37.000 | 37 | 8 | 0.125 | 36.900 | 0.640 | 37.000 | 1.125 | 37.125 |
| 38.000 | 38 | 8 | 0.125 | 37.900 | 0.640 | 38.000 | 1.125 | 38.125 |
| 39.000 | 39 | 8 | 0.125 | 38.900 | 0.640 | 39.000 | 1.125 | 39.125 |
| 40.000 | 40 | 8 | 0.125 | 39.900 | 0.640 | 40.000 | 1.125 | 40.125 |
| 41.000 | 41 | 8 | 0.125 | 40.900 | 0.640 | 41.000 | 1.125 | 41.125 |
| 42.000 | 42 | 8 | 0.125 | 41.900 | 0.640 | 42.000 | 1.125 | 42.125 |
| 43.000 | 43 | 8 | 0.125 | 42.900 | 0.640 | 43.000 | 1.125 | 43.125 |
| 44.000 | 44 | 8 | 0.125 | 43.900 | 0.640 | 44.000 | 1.125 | 44.125 |
| 45.000 | 45 | 8 | 0.125 | 44.900 | 0.640 | 45.000 | 1.125 | 45.125 |
| 46.000 | 46 | 8 | 0.125 | 45.900 | 0.640 | 46.000 | 1.125 | 46.125 |
| 47.000 | 47 | 8 | 0.125 | 46.900 | 0.640 | 47.000 | 1.125 | 47.125 |
| 48.000 | 48 | 8 | 0.125 | 47.900 | 0.640 | 48.000 | 1.125 | 48.125 |
| 49.000 | 49 | 8 | 0.125 | 48.900 | 0.640 | 49.000 | 1.125 | 49.125 |
| 50.000 | 50 | 8 | 0.125 | 49.900 | 0.640 | 50.000 | 1.125 | 50.125 |
What is the NPT Chart?
The NPT chart details the dimensions of tapered threads used in pipes and fittings. These threads ensure a tight seal, preventing leaks in fluid and gas systems. The taper on the threads allows them to compress as they are tightened, creating a secure connection.
The NPT standard is maintained by the American National Standards Institute (ANSI), and its widespread use across industries highlights its importance. From plumbers to engineers, understanding the NPT chart ensures that projects are completed accurately and efficiently.
Key Features of NPT Pipe Threads
- Tapered Design: The threads are designed to taper, which ensures a tighter seal as the male and female threads are tightened together. This taper is generally 1 ¾ inches per foot.
- Standardized Dimensions: NPT threads adhere to strict standards, making it easier for professionals to match pipes and fittings from different manufacturers.
- Thread Engagement: Proper engagement of threads is crucial for achieving a leak-proof connection. The chart provides dimensions for hand-tight engagement and maximum thread engagement.
- Wide Application: NPT threads are used in plumbing, automotive, and industrial systems, making them a versatile choice for various applications.
Why is the NPT Chart Important?
The NPT chart is essential for professionals working with threaded connections. Here are a few reasons why:
- Ensures Compatibility: The chart helps you avoid mismatched threads, which could lead to leaks or system failures.
- Improves Efficiency: Knowing the correct dimensions saves time and reduces errors during installation.
- Promotes Safety: A secure and tight connection minimizes the risk of leaks, which can be dangerous in systems carrying hazardous fluids or gases.
- Universal Reference: Since NPT threads are standardized, the chart serves as a universal reference for various industries.
NPT Chart Table
Below is a detailed table providing the dimensions of common NPT threads. This table is a handy reference for selecting the correct thread size and ensuring compatibility:
How to Use the NPT Chart?
- Determine the Nominal Pipe Size: Identify the pipe size from the chart.
- Match Thread Pitch: Ensure the threads per inch align with the desired fitting.
- Verify Dimensions: Cross-check the outside diameter (D) and other metrics for accuracy.
- Measure Engagement: Use the engagement length (L1 and L2) to confirm a tight fit.
Applications of NPT Threads
NPT threads are found in a wide range of applications. Here are some common uses:
- Plumbing Systems: NPT threads are used in water supply systems, drainage systems, and HVAC (heating, ventilation, and air conditioning) installations. Their ability to create a secure and leak-proof seal is invaluable in these applications.
- Manufacturing Equipment: In industries that use high-pressure systems, NPT threads are commonly used in hydraulic and pneumatic equipment.
- Automotive Industry: Many fuel lines, cooling systems, and air conditioning systems in vehicles rely on NPT threads for secure connections.
- Oil and Gas: In oil refineries and gas pipelines, NPT threads play a crucial role in maintaining safety and efficiency.
Tips for Working with NPT Threads
- Use Thread Sealant: Apply a thread sealant or Teflon tape to ensure a leak-proof connection.
- Avoid Over-Tightening: Over-tightening can damage the threads or cause the fitting to crack.
- Check for Standards: Always ensure the fittings meet ANSI or equivalent standards for compatibility.
- Inspect Threads: Check for any damage or wear on the threads before installation.
Final Thoughts
The NPT chart is an essential tool for professionals working with threaded pipes and fittings. By understanding the dimensions and specifications, you can ensure reliable and efficient connections in your projects. This chart not only saves time but also promotes safety and efficiency in various systems. Bookmark this guide for quick reference and enhance your workflow today!
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