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British Standard Whitworth(BSW) is an imperial-unit-based screw threadstandard, devised and specified by Joseph Whitworthin 1841 and later adopted as a British Standard. It was the world's first national screw thread standard, and is the basis for many other standards, such as BSF, BSP, BSCon, and BSCopper. History.
British Standard Pipe ( BSP) is a set of technical standards for screw threads that has been adopted internationally for interconnecting and sealing pipes and fittings by mating an external ( male) thread with an internal (female) thread. It has been adopted as standard in plumbing and pipe fitting, except in North America, where NPT and ...
British Standard Cycle ( BSC or BSCy or CEI) is a British Imperial screw thread standard. Unlike other major British imperial thread standards ( British Standard Whitworth and British Standard Fine) the thread runs at a 60 degrees rather than a 55 degrees angle. All sizes 4 inch and larger use 26 threads per inch (tpi), making them similar to 1 ...
The taper rate for all NPT threads is 1 inch of diameter in 16 inches of length (3 ⁄ 4 inch per foot or 62.5 millimeters per meter) measured by the change of diameter (of the pipe thread) over distance of thread.
Sizes that may interchange, depending on the precision needed, include 2 mm (close to 5 ⁄ 64 inch (1.98 mm)), 4 mm (close to 5 ⁄ 32 inch (3.97 mm)) and 8 mm (close to 5 ⁄ 16 inch (7.94 mm)). In reality, a wrench with a width across the flats of exactly 15 mm would fit too tightly to use on a bolt with a width across the flats of 15 mm.
Pitch and TPI describe the same underlying physical property—merely in different terms. When the inch is used as the unit of measurement for pitch, TPI is the reciprocal of pitch and vice versa. For example, a 1 ⁄ 4-20 thread has 20 TPI, which means that its pitch is 1 ⁄ 20 inch (0.050 in or 1.27 mm).
The pitch diameter of the thread is simply OD − 0.6p and the minor diameter is OD − 1.2p. The thread angle is different from that used by Whitworth (55°), US Unified threads (60°) and ISO Metric (60°) so BA fasteners are not properly interchangeable with Whitworth or metric ones even when the pitch and diameter are similar enough that ...
Designation. A metric ISO screw thread is designated by the letter M followed by the value of the nominal diameter D (the maximum thread diameter) and the pitch P, both expressed in millimetres and separated by a dash or sometimes the multiplication sign, × (e.g. M8-1.25 or M8×1.25). If the pitch is the normally used "coarse" pitch listed in ...