US Patent 9272791 Aircraft refuel system piping

The invention provides a pipe 100 for an aircraft refuel system, the pipe comprising an outer section 200 making up a pipe wall, the pipe wall having an outer and inner 230 surface, a surface texture 310 on the inner pipe wall surface, the surface texture comprising projections 311 projecting inwards from the inner pipe wall surface towards the centre of the pipe. The surface texture may be riblets 311 and may be coated with an anti-bacterial coating 340. The surface texture may be formed from a layer of conductive material, in the form of a foil 300. The outer section 200 may be made from a non-conductive, preferably composite material. The invention also provides a method of manufacturing piping for an aircraft refuel system using a mandrel 400.