Piping thread standards
Most piping threads are produced to national or industry group standards describing threads form - threads angle, pitch and diameter. Common standards are
- ANSI/ASME B1.1-1989, Unified Inch Screw Threads (UN and UNR Thread Forms)
- ANSI/ASME B1.20.1-1983 (R1992), Pipe Threads, General Purpose (Inch)
- DIN 2999, Pipe threads for tubes and fittings - parallel internal thread and taper external thread
- ISO 724 ISO general-purpose metric screw threads -- Basic dimensions
In general pitch refers to threads per inch (TPI) for fractional screw threads and pipe threads. For metric screw threads pitch refers to the distance between threads.
Common piping thread standards in the United States are
- NPT - American Standard Pipe Taper Thread (also known as ANSI/ASME B1.20.1)
- NPTF - National Pipe Thread Tapered Fine
- NPTR - American Standard Taper Railing Pipe Thread
- NPS - American National Standard Straight Pipe Thread
- NPSC - American Standard Straight Coupling Pipe Thread
- NPSM - American Standard Straight Mechanical Pipe Thread
- NPSL - American Standard Straight Locknut Pipe Thread
Other common piping thread standards
- ISO 7 Tapered Pipe Threads - also known as DIN 2999, BSP 21, JIS B0203
- ISO 228 Parallel Pipe Threads - equivalent to DIN ISO 228/1, BSP PL, JIS B0202, G 1/8 and G 1/4 etc.
- BS 21 BSP British standard pipe thread - Whitworth (withdrawn)
More about standards applied for piping threads .