1. What is NPT Thread?

NPT (National Pipe Taper) is a U.S. standard for tapered threads used on threaded pipes and fittings. The taper is 1 inch in diameter per 16 inches of length (1/16" per inch).

2. How Does the Calculator Work?

The calculator uses the standard NPT taper formula:

Where:

• \( Length \) — Thread engagement length in inches
• \( \frac{1}{16} \) — Standard NPT taper rate (inches per inch)

Explanation: The taper causes the diameter to increase by 1/16 inch for every inch of length.

3. Importance of Taper Calculation

Details: Proper taper calculation ensures leak-proof joints in pipe connections and correct thread engagement.

4. Using the Calculator

Tips: Enter thread length and nominal diameter in inches. Select thread type (NPT or NPTF). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between NPT and NPTF?
A: NPTF (Dryseal) threads are designed to seal without sealant, while NPT typically requires thread sealant.

Q2: How many threads per inch does NPT have?
A: It varies by size. For example, 1/8" NPT has 27 TPI, while 1" NPT has 11.5 TPI.

Q3: What's the proper engagement length?
A: Typically 3-5 threads for hand-tight engagement, plus 2-3 turns with a wrench.

Q4: Can I use this for metric tapered threads?
A: No, metric tapered threads (like BSPT) have different taper rates and standards.

Q5: How accurate is this calculator?
A: It provides theoretical values based on standard taper. Actual measurements may vary slightly.