NPT is an acronym for National Pipe Tapered Threads, also known as ANSI/ASME B1.20.1 pipe threads. It is a standard in the United States for measuring tapered threads on threaded pipes and fittings. This standard is widely accepted throughout North America. Pipe thread sizes are typically determined by the pipe’s internal diameter (ID) or flow length. NPT connections rely on thread deformation, a metal-to-metal sealing design in which the threads of the connectors form together. Threaded pipes can provide an excellent seal for hydraulic fluid-filled pipelines. MPT, MNPT, or NPT (M) for male exterior threads and FPT, FNPT, or NPT(F) for female internal threads. NPT threads are not compatible with NPS (National Pipe Straight) threads. Learning how to make NPT threads in Solidworks gives a user the skills to create a tapered line instead of straight threads on a bolt, which will pull tighter, resulting in a tighter seal. A sealing compound or PTFE (Polytetrafluoroethylene) tape must be used to ensure a leak-free seal. The Npt characteristics include: The angle formed by the taper and the pipe’s central axis is 1° 47′ 24″ (1.7800°); balanced truncation of roots and crests; thread angle of 60°; Threads per inch are used to measure pitch (TPI).

The NPT thread sizing chart contains exterior and interior pipe thread information. All NPT threads have a taper rate of 1/16—3/4 in. per foot (62.5 mm per m), which is measured by the change in diameter over distance. The outside diameter (OD) of a pipe or fitting must also be measured; both the TPI and OD are required for accurate thread size identification because the same TPI can be found in multiple sizes. Standard sizes include 1/8, 1/4, 3/8, 1/2, 3/4, 1, 1 ¼, 1 ½, and 2 inches. These can be found on most US suppliers’ pipes and fittings. Dimensions less than 1/8 in. are occasionally used for compressed air, but diameters greater than two in. are less prevalent, owing to different connecting methods with these larger sizes.

How To Make NPT Thread In Solidworks

The technical usefulness of NPT threads cannot be overemphasized, Follow these steps to know how to make NPT thread in Solidworks:

Step 1: Create a base feature—typically a bar. You can create a new part on the front plane.

Step 2: Create a sketch, make an extruded bar stock, and give it two and a half inches in diameter and 3 inches in length. Again, you could make the image quality better depending on your preferences.

Step 3: Create a taper, a revolve cut outside the bar stock. You will cut everything on the outside, leaving just enough for the filling. Create a closed contour that will revolve around this center line.

Step 4: Sketch the taper so that the lines snap to each other so that they complete a closed contour. You make sure the center line is vertical and snaps to the bus stock’s middle point. Convert the blue lines to black because blue means undefined, and you don’t want undefined lines in your sketch.

Step 5: Make the height of the undercut half an inch. It is the cylindrical portion of the taper, and it must match the NPT thread’s nominal diameter from the chart below. You create the angle for the taper by calculating the arctangent of 1/16, which is 3.5763 degrees, but we want the angle on the radius so that you can divide the angle by 2.

You also have to give the length of the threaded portion, 0.7 inches, and the measurement of the nominal cylindrical diameter, 0.1 inches.

Step 6: After creating a closed contour, revolve it around a central line, choose a sketch, followed by an insert, select cut, and click the revolve button.

Step 7: Cut threads.

First – create a profile and a helix. You will create a closed shape for the cutter tool and ensure that the triangle lines are equal. Next, create a center line and insert a point in the middle of one of the triangle’s lines. The point will define the pitch diameter, which is 2.690, which is the beginning of the thread. After creating the actual contour with solid lines by overlaying the construction lines with solid lines on the triangle, the triangle stimulates the tool cutter to come in and cut the taper.

The route length is calculated using an equation which is the value of pitch / 8, which is constant in the external thread.

Step 8: After defining the pitch diameter, the angle is set to 60 degrees. The last step is to determine the height of your thread from the roots to the crest, and it’s a book value obtained from the chart above. Finally, after defining all the necessary parameters, snap the point to the contour of the metal.

After creating a helix feature, the guide for the contour to cut through, select the surface and convert sharp edges into a sketch.

Step 9: After setting all the dimensions, you will see that the taper and helix follow each other.

Step 10: The last step is to create the actual cut, so you can do so by clicking insert and selecting sweep cut to create the thread. You can do a little thread relief to convert all the edges into hard lines by using an insert and going to features to extrude through, i.e., making an extruded cut through everything, which will clean up the parts and create relief for the threads.

You could also add a chamfer on your threads’ minor diameter.

These steps basically guides you on how to make NPT thread in Solidworks, in case of any errors, go over the steps properly without omission.

Issues with NPT Threads

NPT threads were initially designed for plumbing (60 psi) rather than hydraulic systems. They have, however, been employed in hydraulic systems for many years. Pipe threads are not recommended for high-pressure applications because they leak more than any other type of connection. As previously stated, NPT threads require some sealer to be applied to the threads before assembly. NPT threads are more prone to leakage than Dryseal threads, but both thread types will leak if under-tightened. Although no common tightening standard has been established, keep in mind that tightening requirements vary depending on the re-use and type of sealant used. It’s also worth noting that overtightening can cause the female port to break.

Conclusion

This article teaches how to make NPT thread in Solidworks step by step because it is a necessary skill to understand. You can now apply your knowledge to develop more sophisticated 3D CAD models.