The standard specifies general provisions for inspection using a low-temperature chamber, magnifying glass and low-temperature media (e.g. liquid hydrogen, liquid oxygen, liquid nitrogen). The specimen must be prepared by the same process as the product under inspection, and the substrate material and pretreatment should also be consistent. The number of specimens is not less than four, one of which is used for comparison. The inspection method involves a comprehensive inspection of the surface test layer status and recording the details. The specimen or scaled analog is then placed in the adjusted low-temperature chamber or low-temperature medium as required by the design document. After a predetermined time is reached, it is removed and placed at room temperature. After the sample returned to room temperature, observed with 4 to 5 times magnifying glass and compared with the untested surface of the sample.