What does the acronym "NPT" stand for in relation to pipe fittings?

The acronym "NPT" stands for National Pipe Tapered, which refers to a standardized system used for threaded pipe fittings in the United States. NPT is characterized by a tapering design that allows for a tighter seal as the threads are tightened together. This tapering helps to create a stronger mechanical grip between the fittings, reducing the likelihood of leaks in pressurized systems.

NPT threads are commonly used in a variety of applications, including plumbing and industrial piping, where gas and liquid tightness is crucial. The standardization of these threads ensures compatibility between different manufacturers' fittings, making it a widely accepted choice for many engineering and construction projects.

The other options presented do not accurately represent the meaning of the acronym. For instance, while "Normalized Pipe Thread" and "National Pipe Type" suggest some relation to pipe fittings, they are not recognized standards. "New Pressure Test," on the other hand, refers to a procedure rather than a classification of threading, thereby confirming that National Pipe Tapered is definitively the correct representation of NPT.