Abstract: A sleeve for sealing an annular gap between opposed co-axial surfaces of a slip joint includes a tubular body formed from a metallic material and having a first end, a second end, a center section between the first and second ends, and a longitudinal cross-sectional profile having a plurality of bendable curves. The sleeve is shaped so that two or more of the bendable curves contact each opposed coaxial surface to form two or more circumferential lines of contact with each opposed coaxial surface. The sleeve further includes a self-protective oxide undercoat layer that protects the metallic material and a lubricous overcoat layer that provides lubricity to the contact surfaces when the sleeve is exposed to temperatures greater than about 600° C.