DS EN 10226-1:2004 Pipe Threads Where Pressure Tight Joints Are Made On The Threads - Part 1: Taper External Threads And Parallel Internal Threads - Dimensions, Tolerances And Designation Defines 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.