Abstract: A metal lined pressure vessel has a filament wound shell with a curved polar end. The shell has polar opening, and a metal internal liner is substantially surrounded by the shell and has an opening aligned with the polar opening in the shell. A boss or fitting is disposed at the polar end and has a tubular neck projecting through the opening in the shell and an annular flange which extends radially from an inner end of the neck within the vessel. A shear stress relieving layer is bonded between the boss and the metal liner to relieve stresses induced when the vessel is pressurized, and the liner is affixed to the boss continuously about the opening in the liner for isolating the layer from fluid in the vessel.