The invention concerns a protective sleeve for fluid circulation tube made of an interwoven fiber structure formed by a strip (10) of interwoven fibers comprising at least a pocket (11) extending in the transverse direction of the strip (10) and including a spring (13) housed in the pocket (11) and designed, in a stable equilibrium position, to maintain the protective sheath closed by overlapping of the longitudinal edges (10c, 10d) of the strip. The invention is useful in particular for thermal protection of an exhaust gas recycling duct in a motor vehicle.