B s p

[Richard Farrant]

Originally Posted by Perry Kitson

British pipe sizes are designated BSP.Tr for tapered threads, and BSP.Pl for parallel threads. Pipe sizes are the same both sides of the pond, and there is no 7/8 pipe.
There is however a BSP.F thread that is similar to our NS(National Special) series of thread. The BSP that is being referred to for the spindle threads is the BSP.F, 7/8-14 which has a O.D. of 1.189in. The BSP.F series of thread uses the same nominal diameters as the British pipe schedule, but have added a few sizes in between the standard pipe sizes to give a better range of thread sizes.

Perry

Hi Perry,
Being in England and working in engineering for over 40 years, I am well acquainted with British Standard threads and use them every day at work still. The designation BSP.F means BS Pipe Fitting thread. One of my old reference books, is dated 1946, a Mechanical Engineers handbook, and it lists all the diameters of BSP thread sizes through the range, inc. the 7/8" which has been discussed. A trap that some may be falling in is that certain sizes like 1/4", 3/8", 1/2" are internal pipe sizes, as for water and gas, etc., with some thread sizes not relating to a standard pipe internal diameter. But pipe threads are also used in hydraulics and compressed air and may not be used in conjunction with external threading of pipe, but for other uses. It may be confusing with the size not relating exactly to the thread diameter, but those who use this thread are well aware as OD is shown in the thread tables. With the wealth of metric and US thread forms in the world today, we have to check TPI and angles on unfamiliar applications at times but BS is an excellent thread form and far superior to the rest ..... in my long experience.