FAQs - NPT vs. BSPT Pipe
Why are there both NPT and BSPT threads?
NPT threads are commonly used in the United States. BSPT are widely used in other countries.
Q. What do the initials mean?
BSPT -British Standard Pipe Taper
BSPP -British Standard Pipe Parallel
NPT -National Pipe Taper
NPS -National Pipe Straight
Q. Can NPT or NPS be fitted to BSPT?
Never try to mate a BSP fitting with an NPT or NPS fitting if the pressure holding capability is at all critical.
Q. Are NPT/NPS threads compatible with BSPT?
No, the thread forms are different and most have a different pitch.
Q. How are the thread pitches different?
NPT/NPS threads have a 60° included angle and have flattened peaks and valleys ; BSPT threads have a 55° included angle and have rounded peaks and valleys.
Q. How do I determine the pitch?
Use a thread gauge or count the number of threads that fall into a 1" span..