Expansion joints

An expansion joint for use in interconnecting two fluid media containing members to permit relative movement between them in response to thermal, pressure related or vibrational changes, said joint consisting of a flexible, media resistant, sheet material disposed as a sleeve and means attachable to the ends of the sections to which the margins of the sleeve are sealed, at least when said means are so attached, said sleeve then surrounding and isolating the flow path in the area between said sections, said material including at least one reinforcing fabric substrate including two series of parallel strands the orientations of which present a criss-cross pattern and with all the strands of both series diagonal with respect to the flow path, and surface layers of a flexible media resisting material having a degree of elasticity whereby said changes on the joint, urging perimetric changes of the material are accommodated by the reorientation of the substrate strands thereby allowing the material substantially throughout the length of said sleeve to stretch and recover in directions substantially normal to said flow axis.