NPT, National Pipe Thread, is a standardized thread type in the United States and several other countries. It is primarily used for joining and sealing pipes and fittings in plumbing and other applications where a watertight seal is crucial.

Tapered Profile: Unlike straight threads, NPT threads are tapered. This means the diameter of the threads changes along their length, ensuring a tighter and more secure fit.

Standardization: Governed by the American National Standards Institute (ANSI), ensuring consistency in design and application.

Sealing Method: When two NPT threads are tightened, their flanks compress against each other, forming a seal. Thread sealants like PTFE tape or pipe dope are commonly used to enhance the seal.