What size is a 1/4 NPT?

As a general “rule of thumb” an NPT thread is approximately 1/4" (0.25”) larger than its “name.” For a 1/4" NPT fitting the “nominal” OD is 0.533”. NPT fittings are slightly tapered so the “nominal” diameter is the diameter in the middle of the threaded portion, as measured by the top (crest) of the threads.

What are NPT thread sizes?

Commonly-used sizes are 1/⁄8, 1/⁄4, 3/⁄8, 1⁄/2, 3⁄/4, 1, 1 1⁄/4, 1 1⁄/2, and 2 inch, appearing on pipes and fittings by most U.S. suppliers.

What does 1/8 NPT stand for?

A 1” NPT MALE CONNECTION HAS AN OUTSIDE DIAMETER (OD) OF ABOUT 1.3”. AN 8” PIPE HAS AN OD OF ABOUT 8.6”. THE MEASUREMENTS ARE “TRADE SIZES.” THAT MEANS THEY ARE UNIFORM SIZES ACCORDING TO THE DIAMETER OF THE PIPE OR FITTING THAT THEY CAN BE USED WITH.

Is NPT measured by ID or OD?

How are they measured? NPT fittings are listed by the "standard" inner diameter (I.D.) of the fitting. (We put "standard" in quotes because the I.D. of the fitting will vary, depending on the manufacturer.) The outer diameter (O.D.) of the threads is usually about 1/4 (0.250) in.

How do you measure NPT pipe size?

To determine the size of a pipe, the outside diameter of each pipe or fitting must be measured and compared to the table for size identification. For example, a 3/4" NPT pipe thread has an outside diameter of 1.050 inches. Each thread size has a defined number of threads per inch (TPI).

How to measure NPT Fittings and pipe sizes

What does NPT mean in fittings?

NPT (or National Pipe Taper) is a U.S. standard for tapered threads widely used on pipes and fittings for over 100 years.

What is the taper on a NPT thread?

Every NPT thread has a taper rate of ¾-inch per foot, or 1/16-inch per inch of length. The taper rate is determined by comparing the change in thread diameter over the length of the pipe. The taper angle itself Is 1° 47" 24"" (1.7899°).

What is NPT thread pitch?

NPT/NPS threads have a 60° angle and have flattened peaks and valleys (Sellers thread form) where as BSP threads have a 55° angle and have rounded peaks and valleys (Whitworth thread form). NPT and BSP thread pitches (threads per inch) are listed below.

Are all NPT threads tapered?

Both NPT and NPS have the same thread angle, shape, and pitch (threads per inch). However, NPT threads are tapered and NPS threads are straight (parallel). Both threads have a 60° included angle and have flat peaks and valleys.

How do you read a pipe fitting size?

To get a truly accurate reading of the pipe size, you should measure both the threads per inch and the outside diameter (or inside diameter if it's a female pipe thread). For male pipe threads, be sure to measure the outside diameter at the widest point of the threads.

Is NPT male or female?

NPT has a tapered male and female thread which seals with Teflon tape or jointing compound. Pipe threads used in hydraulic circuits can be divided into two types: Jointing threads are pipe threads for joints made pressure tight by sealing on the threads and are taper external and parallel or taper internal threads.

What is a 1/4 NPT thread?

As a general “rule of thumb” an NPT thread is approximately 1/4" (0.25”) larger than its “name.” For a 1/4" NPT fitting the “nominal” OD is 0.533”. NPT fittings are slightly tapered so the “nominal” diameter is the diameter in the middle of the threaded portion, as measured by the top (crest) of the threads.

How do I measure pipe size?

To find it, measure around the circumference of the pipe with flexible measuring tape. Divide the circumference by pi, or about 3.14159. For example, if the circumference is 12.57 inches (319 mm), you would divide by pi, and get an outside diameter of about 4 inches (100 mm).

How do you measure thread size?

Determine the diameter and the length of the threaded area.

Measure from the bottom of the head to the end of the threaded area in millimeters. For instance, it might be 8 millimeters. Then, measure the diameter (width) of the threaded area in millimeters. This might be 4 millimeters across.

Is gas thread the same as NPT?

The NPT thread (Nationale Pipe Thread) represents the American standard compliant with the AISI B1. 20.1 standard and is the second most used in the field of hydraulic fittings. Compared to the GAS thread, it has a 60 ° thread angle which results in a larger pitch (which means a smaller number of threads per inch).

Do NPT threads need Teflon tape?

NPT threads are designed to be used with a sealing compound such as Teflon tape to create a leak-free seal, whereas NPTF threads form a mechanical seal by crushing the entire thread form. If NPT is used without a sealing compound then there can be leakages or other unpleasant issues.

Can you reuse NPT fittings?

NPT fittings can be reused but require careful inspection for thread damage from overtightening. In general, do not reuse NPTF fittings.