A composite strip 10 windable to form a helical pipe for transporting fluid is disclosed. The composite strip comprises: an elongate plastic strip 11 having a base portion 12, the base portion 12 having an upper side defining an outer face 15; and at least one lengthwise extending composite rib portion 20 upstanding from the outer face 15 of the base portion 12. The rib portion 20 has a distal end 23 remote from the base portion 12. The composite rib portion comprises: an elongate inboard reinforcing member 30 disposed within or adjacent to the base portion 12; an elongate outboard reinforcing 40 member disposed within the distal end 20 of the rib portion 20 parallel to the inboard reinforcing member 30; and an elongate intermediate plastic web 23 portion extending between the inboard and outboard reinforcing members 30, 40. When wound into a helical pipe, the composite rib portion 20 reinforces the pipe against radial crushing loads.