18-27 NPT - Internal (Fitting) Basic Thread Dimensions. For interpertations of the terms scroll down to the drawings below the table. Property. Inch. mm. Nominal Pipe Size (Ø) 1/8".Metric BSF/BSW, UNC and UNF Conversion Table. Optimas are a full-service supply chain and manufacturing solutions provider. Before you design your next product or make updates to an existing product, consider partnering with Optimas to take advantage of our many capabilities. The table below can be used to help find the nearest sized metric
BSPT& BSPP Threads Dimensions. Thread size refers to the nominal bore of the pipe. Subtract approx. 1/4″ (6mm) from thread diameter measurement for nominal pipe size. Pitch is Threads Per Inch (TPI).
WheneverNPT is specified, a depth of tap callout is not required because there are standards specified according to the tap size. The engagement is given in inches in the Handbook but if you convert the distance to number of threads per inch you will always get a number that's somewhere around 3-6 threads.
NPT- National Pipe Thread Tapered - is a U.S. standard for tapered threads used to join pipes and fittings is defined by ANSI B1.20.1 Pipe Threads, General Purpose, Inch31/2" 3.500" 3" 8 1.2000 4" 4.000" 3-1/2" 8 1.2500 4-1/2 4.500" 4" 8 1.3000 Two common pipe thread sizes exist, the tapered National Pipe Thread (NPT) and the straight National Standard Free-Fitting Straight Mechanical Pipe Thread (NPSM). The tapered threads are for joining and sealing, the straight threads are only for joining.
