Quick look: little tips on gauge threads

Thread Content

Threaded connections I. Metric threads: A type of thread standard, also known as metric threading; the main difference from imperial threads is that the pitch is measured in millimeters. For example: M20×1.5 means that the nominal diameter of the thread is 20 mm, and the pitch (also known as thread spacing) is 1.5 mm. Second, NPT threads: NPT is an abbreviation for National (American) Pipe Thread; it is a type of tapered pipe thread based on American standards, and it is used in North America. Also known as American thread; the thread size is expressed in inches. For example: 1/2NPT means 1/2 inch tapered pipe thread. III. G thread is also known as imperial thread. Marked as G denotes cylindrical threads. The thread size is expressed in inches. For example: G3/4 means 3/4 inch cylindrical thread. Note: 1. The biggest difference between metric threads and NPT/G threads is the unit used to indicate thread size ； 2. The biggest difference between NPT threads and G threads is that the thread shapes are different ； 3. One inch = 25.4 mm ； 4. The pipe diameter refers to the inner diameter of the pipe. Due to the different wall thicknesses, the outer diameters also vary; for example, there are multiple options for the outer diameter of 4-inch pipes. In the imperial system, 1 inch is divided into 8 fractions; therefore, 4 fractions equal 1/2 inch, 6 fractions equal 3/4 inch, and 8 fractions equal 1 inch. 4 points, 6 points, and 1 inch are imperial units. 4-pipe 1/2\"—diameter 12.5mm; 6-pipe 3/4\"—diameter 19mm; 1-inch pipe 1\"—diameter 25.4mm. Galvanized pipes with 5 or 6 ports can be directly fitted with 3/4 NPT and G3/4 threaded fittings; if a 3/4 NPT fitting is used, a tapered pipe thread must be applied to the galvanized pipe ； If connecting to a G3/4 fitting, a cylindrical pipe thread must be applied to the galvanized pipe. 6. Galvanized pipes with a diameter of 4 mm can be fitted with 1/2 NPT or G1/2 threaded fittings; if a 1/2 NPT fitting is to be used, a tapered pipe thread must be applied to the galvanized pipe ； If connecting to a G1/2 fitting, a cylindrical pipe thread must be provided on the galvanized pipe. 7. Other connections require adapters for conversion.