GB/T 21921-2008 "Test method for tensile strength of impermeable graphite materials" specifies the specific steps for determining the tensile strength of impermeable graphite materials, the required equipment and the preparation requirements of the sample, which is suitable for the performance test of such materials. The standard includes the requirements of the test device, the sampling and the preparation method of the sample, and the size and shape of the sample are specified in detail to ensure the accuracy and conformity of the test. The standard is suitable for the tensile strength evaluation of graphite blocks, pipes and adhesive castings, providing a standardized test basis for the analysis of the mechanical properties of graphite materials in practical applications.