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OmniSeal® RACO® spring energized seal is a polymer sealing solution from Omniseal Solutions™, which has been an important part of the aerospace, aerospace, and oil and gas markets for the past 60 years, where extreme sealing performance is required Excellent performance at low temperatures-either in very high (500°F/260°C) or very low and low temperature (-450°F/-268°C) temperature environments. Typical examples include applications in contact with cryogenic fluids such as liquid oxygen, hydrogen or nitrogen. In its 60 years of successful use, the design of RACO® seals has not changed much, although it is still being continuously developed and developed to meet customer and market needs, and represents the most advanced solution in the sealing industry.

OmniSeal® RACO® seals

The OmniSeal® RACO® seal has a specific spring type, which can continuously contact the spring along the entire sealing lip, and adopts a sheath design made of a proprietary Fluoroloy® polymer material. Initially, in various rocket engine projects involving cryogenic liquid propellants, the seal was created to improve the performance of soft elastic seals and hard metal gaskets, and these applications failed many times. The RACO® name is registered by Omniseal Solutions™ in the United States, Canada, Europe, and Japan, and continues to be used in most challenging space applications, especially those that require leakage below 10-3 sccs when measured at LH2 temperature .

RACO® seals are very highly loaded and elastic springs with an average spring load of approximately 8 N/mm circumference. Depending on the application, the load may increase to 15 N/mm or even higher to a circumference of 18 N/mm. Why is such a high load required? This is to support the sheath material when the temperature is very low and the material tends to shrink, with the extreme potential impact of losing contact with the corresponding surface and causing serious leakage. To prevent this dangerous situation, polymer seals are carefully designed to hold the lip in place and balance the contraction.

OmniSeal® RACO® seals

There are other alternatives in terms of sealing ability under low temperature conditions, such as spring-energized metal C-rings; however, their circumference loads are as high as 800 N/mm. These high loads make the installation quite complicated, requiring a large number of high-strength bolts to keep the flange closed and the metal seal in place, thereby increasing the overall cost and weight of the equipment.

RACO® seals are usually used for static applications or slow angular movements, and can be manufactured for internal or external pressure. The seal can fit almost any existing groove size. This aspect has recently been improved, where seals can be used for relatively small grooves, as small as 18 mm in diameter. At the upper limit of the scale, it is almost non-existent, and is more associated with machined polymer sheaths, manufacturing examples of more than 2 m-in the case of the liquid oxygen tank of NASA's space launch system-and can process up to 3 The sheath meters.

Other recent manufacturing improvements include laser welding of springs, which improves the quality of the sealing solution in terms of low leakage performance. The manufacturing process also changes with the development of the market. RACO® seals are cleaned in accordance with the most stringent standards, such as the standards required by the aerospace market (IEST-STD-CC1246E). There are no particles exceeding 300 microns and NRV (non-residual volatilization). Sexual) level is lower than 2.7 mg/0.1 square meter.

Many typical applications where RACO® seals provide the most critical value are static seals in feed lines, valves, or turbo pumps in launch vehicle propellant tanks in the aerospace market, especially with fluids such as LOX or LH2. Since the seal is designed to handle low and high temperatures, it is also effectively used for cryogenic ball valves in the oil and gas industry or rotary joints for marine LNG loading arms, and it also manufactures large diameters.

The 60-year service of RACO® seals has witnessed its historical milestones, from the beginning of the Mercury program, to the Apollo and space shuttle missions, to the upcoming SLS program.

OmniSeal® RACO® seals are used in launch vehicle applications, such as fuel tanks, because the seals in these areas are very important because they contain liquid oxygen or liquid hydrogen and they are easily ignited. Any small amount of leakage will cause a dangerous situation and lead to a potential explosion of the entire launch system. This case study shows how polymer seals can help space dreamers successfully launch and travel to outer space.

This information is derived from materials provided by Omniseal Solutions™ and has been reviewed and adapted.

For more information on this source, please visit Omniseal Solutions™.

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