Glass Tube Air Preheater is recuperative type heat exchange equipment used for low temperature heat recovery. It comprises of borosilicate glass tubes inserted into metallic tube sheets lined with Teflon. The other sides are cladded with special metallurgy sheets. Tube-to-tube sheet joints are provided with special bush / glands to minimize leakage. Glass Air Preheaters recover additional heat from flue gases at lower temperature and are resistant to cold end corrosion.