This specification establishes the requirements for self-locking nuts, wrenching type (i.e., hexagon, double hexagon, and spline drive), made of a corrosion and heat resistant steel of the type identified under the Unified Numbering System as UNS S66286. Classification: a. 220 ksi minimum tensile strength at room temperature and b. 850 degrees F maximum test temperature of parts. Primarily for use in aerospace propulsion systems in temperatures up to approximately 850 degrees were nuts are used with bolts capable of developing 220 ksi axial tensile strength at room temperature, and having UNJ thread form.