There are two types of glass seals available: Compression Seals and Matched Seals. In the design of Compression Seals the expansion coefficients of the steel, glass and ID members are placed in decreasing expansion fashion. This process will maintain the glass under compressive stresses over a wide temperature range. Glass, like ceramic, has little strength when subjected to tension. However, under compression, glass is strong.

If a higher cycle range is needed, you should consider Kovar’ Matched Seals. A fundamental glass sealing process is used to manufacture glass seals in which the kovar metal thermal expansion coefficient matches the glass thermal expansion coefficient. The outcome is a highly effective hermetic seal.