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| MIL-T-50777A(OS)
4.3.2.1 Tensile tests. Tensile tests shall be conducted in accordance with ASTM E 8.
4.3.2.2 Yield strength. The yield strength shall be determined either by the offset method or
extension under load method described in ASTM E 8. In case of dispute, the offset method shall be
used.
4.3.3 Flattening test. Flattening test specimens shall be of the full section of the material
and shall have a length approximately equal to 1 times the outside diameter. Test specimens
representing round tubing shall be flattened sidewise into an oval shape, until the outside minor
axis is not more than eight times the original wall thickness. In case the tube does not flatten
so as to give a uniform radius of bend, suitable jigs may be used to bring about this result; or a
section of not less than inch in length, with the subtended arc not greater than 1/2 or less than
1/3 the circumference of the original tube, shall be removed from the tube and without further
treatment shall be bent around a mandrel having a diameter equal to six times the wall thickness
of the tube. The bend shall be made with the pin placed on the inside surface of the specimen with
the longitudinal axis of the pin and specimen parallel. The bend shall be continued until the
specimen encloses at least 180 degrees of the pin. The outside surface of the tubing shall be
examined for cracks.
4.3.4 Leak test.
4.3.4.1 Pressure test. While the tube is completely immersed in water or other suitable
liquid, an air pressure of 250 psi shall be applied to the inside of the tube for not less than 5
seconds. The tube may be subjected to this test after reduction to size but before the final
anneal. Any tube leakage, as indicated by the formation of air bubbles in the liquid, shall be
cause for rejection.
4.3.4.2 Electromagnetic (eddy current). The eddy current test shall be conducted in
accordance with ASTM E 215. The reference standards specified in the appendix of ASTM E 215 shall
be used to standardize the equipment and ensure proper functioning.
4.4 Criteria of acceptability. If a test specimen fails to meet any of the tests required by
this specification, the lot represented by the sample shall be rejected except when a statistical
sampling plan is provided.
4.4.1 Retests. Retests shall be permitted in accordance with FED-STD-151.
5. PACKAGING
5.1 Packing. All material shall be separated by size, shape, and temper when packed for
shipment. Unless otherwise specified, material shall be packed in substantial commercial
containers of the type, size, and kind commonly used for the purpose in such a manner as to ensure
acceptance by carrier for transportation at the lowest rate applicable and to afford maximum
protection from normal hazards of transportation.
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