This draft European Standard specifies a system for classifying imperfections that may be encountered in thermoplastic welded joints during manufacture and provides examples of imperfections for the following welding processes heated tool butt welding; heated tool socket welding; electrofusion socket welding; hot gas welding; extrusion welding; solvent socket welding. This document does not describe imperfections that may be generated either during service or present before welding such as poor fit up. The correct preparation (e.g. fit up) is described in the relevant welding procedure specification (WPS). This document is also not concerned with the search for the possible influence of these imperfections on the behaviour of joints in relation to the different types of stress to which the latter may be subjected or on methods for preventing such imperfections. This document cannot therefore be used to determine the acceptance of welds, which is defined in EN 16296 [1]. Only imperfections giving rise to discontinuities of materials or changes in shape are taken into consideration in this document, specifying their type, their shape and their positions. This classification can be used to determine the possible origin or causes of the imperfections.