This documents specifies a process using limit gauges, for the validation of taper internal and external threads and parallel internal threads on piping systems components and other products, the dimensions and tolerances of which are detailed in EN 10226-1 and EN 10226-2.The gauging system described may not be suitable, without special precautions, for gauging of threads on injection moulded plastic workpieces.This document does not cover completely all the requirements necessary for full control of thread quality and dimensions. Additional control of tools and equipment and visual inspection during production are required to ensure complete compliance wit