Thread Types
Short List
Summary - there is National Hose and National Pipe as the main 2 types of threads. National Pipe can be tapered or straight, while National Hose is not tapered.
National Hose (NH) = National Standard Thread (NST) = National Hose Thread (NHT). It is often referred to as “fire hose thread”. - [1]- GHT - garden hose Thread, Garden hose thread (GHT) is also referred to as NH. [2]. Same threads per inch as NPT, but not tapered.
- NPSH - national pipe straight hose - same as NPS [3]. Compatible with NPT [4]. NPSH has the same threads per inch as NPT, but without taper. [5]. Verified here [6].
- NPS - National Pipe Straight, same as NPT, but straight. [7]. NPS is not used for high pressure, while NPT can be, such as hydraulics. Does this mean that NPS and GHT are the same?
- NPSM - National Pipe - Straight Mechanical - closure attained by 30 degree compression fit with a swivel - [8]. Only NPT with chamfer will seal properly with NPSM - other NPT threads may not seal.
- NPT - National Pipe - tapered
- R, G - [9]
- BSPP - British Pipe thread parallel
- BSPT - British Pipe thread tapered
- Bolt thread - fine and course
- Metric bolt - fine and course
- Metric pipe straight
- Metric pipe parallel
- UN - [10]
- SAE - with o-rings
Specifications
Long List
Probably hundreds exist all together.
