Thread Types

• NPSM - National Pipe - Straight Mechanical - closure attained by 30 degree compression fit with a swivel - [1]. Only NPT with chamfer will seal properly with NPSM - other NPT threads may not seal.
• NPT - National Pipe - tapered
• R, G - [2]
• 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 - [3]