This International Standard specifies flexure test procedures to determine and classify the fatigue strengths of reconnectable or permanent hydraulic tube joints. The procedure is intended for conducting flexure tests of fittings and joints with high strength hydraulic tubes of various alloys such as corrosion resistant steel, Nimonic, titanium and aluminum alloy hydraulic tube for use on commercial and military aircraft. A mean stress is applied by holding system pressure in the specimens and then flexing in a rotary bending test machine.