A duct coupling apparatus includes a collar portion having a first end and a second end, a flange disposed about the collar portion in a manner that divides the collar portion into an first side and a second side, and a retaining structure extending from a surface of the flange towards the second side of the collar portion. The retaining structure and the collar portion define therebetween an annular region for receipt of a sealing element, such as an o-ring or gasket. The retaining structure prevents the sealing element from extruding outwards and/or failing when under pressure.