This invention relates to flexible tubular conduits or pipes particularly in situations where the conduits need to withstand relatively high pressures. In such cases, the conduits are reinforced by helically wound armor which is compliant in flexure, and profiled to allow each subsequent turn to interlock with the previous turn. The invention provides a locking mechanism (8, 9) located in the axial direction of the tubular conduit comprising one or more projections (8) on one or both radial sides and a corresponding number of sockets (9) on the opposing radial sides, such that the projections (8) of one turn of the winding (10) engaging in the sockets (9) of the next turn of the winding (10), each projection (8) having an enlarged head portion (11) connected to a body by a narrow neck portion (12), and each socket having a corresponding shape to hold the projection captive in the socket, the sockets (8) and projections (9) having dimensions to allow a limited relative rotation between the adjacent turns of the winding and to resist separation, closing, and relative radial movement of the respective turns.