This part of EN 10226 specifies the requirements for thread form, dimensions, tolerances and designation for jointing pipe threads, sizes 1/16 to 6 inclusive, for joints made pressure tight by the mating of the threads. These threads are taper external (designated by R) and parallel internal (designated by Rp) and are intended for use with pipes suitable for threading and for valves, fittings or other pipeline equipments interconnected by threaded joints.