Twin quartz tube ,whose surface is smooth and colorless, has the following characteristics.1、High purity. Its silicon dioxide content is more than 99.9%. 2、Corrosion resisting. It doesn’t react with other acid materials except hydrofluoric acid. 3、Heating resisting. Its melting point is 1750℃. 4、Heat stability better. The coefficient of expansion of quartz glass is very small. It will not break even if you put the quartz glass which has been heated up to 1100 into the normal water. We can gild half of it and decide hydroxyl contents according to the requirement of the customers. The product has strong thermal properties and mechanical performance. The dimensional tolerance is strict. Because of the above, it has been widely used in the electric heating products such as heating tube, electric heating tube, and electric oven etc.