BSB British Standard Brass

The BSB thread is a specialized British thread with a fixed pitch, based on the Whitworth thread. The BSB thread is designed for use with brass pipes, as reflected in the name “British Standard Brass” (Brass = Brass). A characteristic of brass pipes is their consistent wall thickness, regardless of pipe diameter. A thread norm where the pitch increases with thread size could, therefore, lead to problems with brass pipes. Eventually, a point would be reached where the brass pipe is not thick enough to remain stable after cutting the thread at high pitches. This problem does not occur with the BSB thread with its constant pitch.

The BSB thread is an inch thread with a 55° flank angle. The pitch for all thread sizes is 26 threads per inch. There is a risk of confusion with the British bicycle thread BSC, which also has an almost constant pitch of 26 threads per inch. However, both thread types differ in flank angle.

The BSB thread is also referred to as the British Brass Thread, as British Standard Thread mistakenly implies affiliation with the British Standard catalog of norms. The thread designation for the BSB thread consists of the abbreviation BSB and the external diameter in inches, e.g., BSB 1/2″.

In the thread table below, you will find all measurements for the BSB thread in inches and converted into mm. The core hole diameter is also listed in mm, should you wish to cut a BSB thread yourself. We carry dies and taps for the BSB thread in common sizes in our shop, accessible via the corresponding link. For less common dimensions, please contact us, and we will gladly manufacture any desired BSB tap as a custom order.