This specification covers the requirements for high quality,
self-locking nuts for use in temperatures up to 235 degrees C in
conjunction with bolts and screws having threads in accordance with
FED-STD-H28/21. These nuts are divided into classifications depending
upon their axial tensile stress ratings as follows:

          CLASS          MINIMUM AXIAL TENSILE STRESS RATING (MPa)
          -----          -----------------------------------------
          I                             900
          II                          1 100
          III                         1 250
          IV                          1 550