VerroLoc circular flange ring system or circular duct connectors are designed specifically to provide an economical method of jointing for circular ducts, suitable for straight seamed or spirally wound ductwork. The VerroLoc system comprises two flange profiles produced to suit the required duct diameter; each flange is complete with an integral sealant providing an airtight ductwork connection when correctly fitted to the end of the duct section. On site the duct sections are assembled using the provided VerroLoc closure ring, the accuracy of our production ensures that a minimum amount of effort is required to fit the flange on to the duct. Our VerroLoc Circular Flange Ring System reduces fabrication and installation time of conventional RSA flanges and provides easy removal of ductwork sections for cleaning and maintenance purposes. In the absence of established industry testing procedures, the VerroLoc Circular Flange Ring System was independently tested in accordance with the HVCA air leakage test procedures for Ductwork Jointing Systems DW/TM1.