The British Standard Pipe Threads

British Standard Pipe Threads

BSP threads are fairly uncommon in the workshop but widely used in the home where most U.K.

and European plumbing fittings use these threads. The threads are sized not on diameter but on the nominal bore of the pipe to which they are applied. Just to be really odd a ½" pipe doesn′t necessarily have a ½" bore because wall thickness varies with the pressure rating of the pipe. The table below is for tapered threads which are most often used when fitting say a valve with a female thread to a length of steel pipe.