This European Standard specifies requirements and test methods for strength and air leakage of circular ductwork used in air conditioning and ventilation systems in buildings. The standard is intended to establish the mechanical strength and leakage required to verify the fitness for the intended service as installed ductwork. The standard is intended for testing specific installations as well as product series in general under in-situ or laboratory conditions. The requirements and methods are applicable also to rectangular ductwork in respect of air leakage. A recommended procedure, if the permitted air leakage rate is exceeded when testing a specific installation, is given in informative annex A.