Although shelf life is usually a term of storage rather than life, it is important to note that storage conditions affect the useful life. Shelf life varies according to product specifications and compound design. Gasket material is usually stored for several months before use. Therefore, the shelf life is an important consideration for the end user. The failure of the gasket may result from the combination of oxygen, ozone, light, heat, humidity, oil, water, solvent, acid, and vapor. For adhesive-free graphite and PTFE gaskets, the sheets and gaskets of these materials actually have an almost indefinite shelf life. For metal and semi-metal gaskets of graphite or PTFE soft materials, the ideal shelf life under ideal conditions is unlimited. However, in practice, excessive dust may cause compatibility problems with the process, and exposure to moisture and moisture may cause oxidation of metal components. Poor storage conditions can lead to premature deterioration, especially at high temperatures, poor humidity, and strong light.