This standard is one of the environmental testing series standards, primarily used to evaluate the ability of small electrical and electronic products (especially non-hermetically sealed components) to withstand the effects of damp heat aging under accelerated conditions using unsaturated water vapor at high pressure. The core equipment for conducting this test is the unsaturated high-pressure steam constant damp heat test chamber (also known as the high-pressure accelerated aging test chamber). This equipment can precisely control high temperature, high humidity, and high pressure (typically in the range of 1.2 to 2.89 kgf) environments to simulate the penetration effects of damp heat into materials in a short period. The standard specifies in detail the test equipment, severity levels (defined by combinations of temperature and duration), and the complete test procedures. It is applicable for rapid assessment of product reliability but is not suitable for evaluating external effects such as corrosion or deformation.