Abstract: To prevent a bag-in-box type of container comprising a box enclosing a flexible bag from sagging, bulging or leaking when the bag is filled with a pressurized liquid, such as a carbonated beverage, the bag is located either inside a tube of rigid or inelastic material or inside a closed sleeve of elastic material. With the former, transverse platforms with flanges directed towards respective ends of the box are arranged at each end of the tube to transmit pressure from the tube to the box. With a sleeve of elastic material such platforms are not required, but a slotted platform is usually provided for location of the tap which projects from the bag.