FARNBOROUGH, Hampshire, England ‚– For years, Simrit has been on the forefront of perfluoroelastomer (FFKM) material design and production with its Simriz‚® brand of proprietary compounds. One of the supplier‚’s latest materials ‚– Simriz‚® 498 ‚– recently aided a major regional jet manufacturer in drastically reducing its sealing-related warranty issues.
According to Simrit, the superior resilience of Simriz materials makes them an excellent choice for demanding environments where protection against aggressive chemicals and tight sealing is required. Simriz 498 is a high-temperature, low-compression set compound that was specifically developed for applications where temperatures exceed 300 degrees Celsius. The black FFKM material offers outstanding chemical and solvent resistance, including compatibility with nitric acid and amine chemicals.
As an example of how the Simriz 498 compound keeps flights in the air, Simrit cites the following application case analysis.
Issue: A regional commercial jet company was encountering leaks in its bleed air systems used in a variety of applications (heating, flaps, slats). The leaks were not only grounding aircrafts ‚– causing flight delays and lost revenue ‚– but also creating warranty issues for both the airframe manufacturer and bleed air system component manufacturer.
The problem was isolated to the failure of the competitive seals made from FFKM materials. Additionally, bleed air seal leaks were also identified by Pareto analysis as the major warranty item for this aircraft.
Investigation: Extensive evaluations were conducted in Simrit‚’s lab, including: detailed measurement of bleed air duct glands and construction of test fixtures to simulate the application hardware; long-term compression set testing comparing Simriz 498 O-rings to competitive materials at worst case high temperature extremes; and detailed measurement of mating components during the seal testing.
In testing, the competitive materials showed excessive compression set and seal rupture at long-term exposure, as well as excessive corrosion of mating Inconel and titanium metal components during high temperature exposure. Alternatively, Simriz 498 seals tested superior to competitive materials, demonstrating greater resistance to compression set and negligible mating component corrosion.
Simrit also conducted a 5,000 flight hour examination of trial seals in Simriz 498. When compared to lab testing, Simriz 498 seals showed they had more than two-thirds of their expected service remaining life after 5,000 flight hours ‚– easily reaching the airline target of 10,000 flight hours before the overhaul of bleed air systems (where competitive seals do not).
Additionally, to eliminate the possibility of assembly issues, Simrit added part markings to Simriz 498 seals to give a visual cue to the mechanics to Poka Yoke the assembly process. This method is not offered by the competition.
Solution: Regional jet operators switched to Simriz 498 seals and eliminated bleed air systems seal failures as the main warranty issue with the aircraft.
::Design World::
Filed Under: Aerospace + defense, Seals • gaskets • O rings, Materials • advanced