Defines the requirements and test methods for multiwall system chimneys working under wet conditions (in the following expressed as 'wet chimney') with pressure with pressure type N1, N2 or P1 according to EN 1443 and a working temperature below or equal T600 according to EN 13063-1, in which the products of combustion conveyed to the atmosphere through clay/ceramic flue liners. Marking and inspection are also covered by this document.