How do you identify BSP and NPT threads?

by | Aug 30, 2023 | News

BSP (British Standard Pipe) and NPT (National Pipe Thread) are two different standards for pipe threads, and they are not directly interchangeable due to differences in thread angle, pitch, and shape. Here’s how you can identify BSP and NPT threads:

Jianzhi BSP pipe fittings

Thread Profile:

BSP Threads: BSP threads have a flat crest and a rounded root. The thread angle is 55 degrees for both internal (tapered) and external (parallel) threads.

NPT Threads: NPT threads have a tapered profile, meaning the diameter decreases along the length of the thread. The thread angle is 60 degrees.

Thread Pitch:

BSP Threads: BSP threads are often specified with the number of threads per inch (TPI) for imperial sizes or the pitch in millimeters for metric sizes.

NPT Threads: NPT threads are specified by the number of threads per inch (TPI) for both tapered and straight threads.

Thread Direction:

BSP Threads: BSP threads can be either right-handed or left-handed, but right-handed threads are more common.

NPT Threads: NPT threads are always right-handed (clockwise) and do not have left-handed variations.

Usage and Geographic Region:

BSP Threads: BSP threads are commonly used in European and Commonwealth countries.

NPT Threads: NPT threads are the standard in the United States and some other countries.

Thread Sealant:

BSP Threads: BSP threads often require the use of sealing materials like thread tape or sealant due to their parallel nature, which doesn’t provide as tight of a seal as tapered threads.

NPT Threads: NPT threads rely on the thread deformation to create a seal, and they also usually require the use of thread tape or sealant to ensure a proper seal.

To identify whether a thread is BSP or NPT, you can measure the thread angle, thread pitch, and determine the direction of the thread. Additionally, you can consult any markings or labels on the pipe or fitting to see if they specify the thread type. It’s important to use the correct type of fittings and connectors for your specific application to ensure a proper and leak-free connection.

Jianzhi BSP pipe fittings

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