Tubing is used to connect all components in an oxygen system and distribute oxygen from the pressure source to all masks in the flight vehicle. Tubing for oxygen systems is normally manufactured from aluminum alloy (5052 aluminum is a common choice). Aluminum is used since the oxygen system pressures are low and aluminum is lightweight. The ends can be flared (in accordance with SAE AS 4330 or equivalent specification) to accommodate standard MS or AN B-nut fittings, or tubing can utilize flareless fittings. Flareless fittings are swaged fittings, where the swaging is accomplished by a swaging tool or a nut that cause a swage to occur when the nut is rotated in the direction of the tube end. Steel or aluminum tubing can be used on high-pressure lines, where the tube wall thickness is chosen appropriately to handle the pressure. Tubing, as well as all oxygen components, must pass proof and burst pressure tests to verify structural integrity.
Flexible hoses are also used in oxygen systems. Hoses are used to connect aluminum tubing to the crew and passenger mask box assemblies. Normally box assemblies are mounted to aircraft interior panels that have relative motion in flight. Hoses accommodate the relative motion as well as accommodate installation tolerances for the box assemblies. Hoses are not used to replace long runs of aluminum tubing. Tubing has the advantage of being rigid and can be mounted to frames ensuring adequate clearance to surrounding structure, wires and other equipment.