Armored carbon rings are radial sealing rings, which are supported by stainless steel or titanium sleeves. They are mainly used in compressors, positive displacement blowers and valves for hot steam application in high temperature area surroundings. Compressors and screw compressors, which work with high sliding speeds, either in high temperature areas or with all kinds of gases or gas mixtures are taking advantage of this sealing type. The combined material is impregnated with antimony to offer the highest possible strength leading to a high lifetime. Carbon rings and stainless steel rings will be combined by a shrinking process, which adds another finishing process to ensure the highest possible rotation accuracy.
The sealing rings are ordered axially behind each other, which results in each ring reducing the pressure. It is necessary to add a cover ring between each one of them.
An important aspect during manufacturing is that the rings have a specific planar surface between each other and between the cover rings in order of ensuring the highest possible sealing function and the correct rotation accuracy. In addition to a perfect surface quality, it is necessary to maximize sealing effects and for minimizing the wear. STB manufactures armored carbon rings in Ra quality down to 1,5 μm to ensure these qualities requirements. This seal type allows, axial gaps of 0,009 – 0,02 mm. So it makes it a good alternative to non-contact labyrinth seals by reducing the energy consumption. Constant designing and developing have made it possible to add more and more application areas for armored carbon seals. Since the seals are not mounted on the shafts they cannot cause regular vibrations which then result in bearing damage. Due to the fact that these seals are made up of 2 different materials, carbon/ carbon graphite and stain-less steel, the coefficient of thermal expansion needs to be adapted to the surrounding temperature.
Armored carbon seals have been a good value solution for complicated dry gas seals and double cartridge mechanical seals for many years. If requested by the customer, we offer extra lettering on the outside surfaces area. This is usually a good solution for field service repairs and after sales service to minimize the possibility of mix-ups and for identifying the right product. STB also takes note by lettering for the used materials. Therefore the products get serial numbers to ensure their traceability over decades. The principle basics of these rings are also applicable as back up seals for dry gas seals. If a dry gas seal has a failure, machinery normally needs a full shutdown within a short time frame. By using armored carbon ring seals it is possible to perform controlled shut downs of machinery without any risk . For valves, armored carbon rings receive an additional thread, which make the seal size longer.
*We provide alternative products for Hohlfeld sealings and fittings.