Simriz® 498 Compound Created Specifically for High-Temperature Aircraft Environments

Simrit FFKM material aids major aircraft manufacturer in reducing sealing-related warranty issues

FARNBOROUGH, Hampshire, England (July 10, 2008)- For years, Simrit- the industrial sealing products division of the Freudenberg and NOK Group- 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.

"Being the single-source developer of Simriz allows us complete oversight to ensure we're producing the best quality materials and sealing technologies. Starting with the base polymer, we design and manufacture all of our products to the specific demands of the application's environment," said Dr. Bob Keller, manager of materials development for Simrit. "In the aerospace industry, using the precise material to create a specific seal is one of the critical elements in keeping our customer's flights where they belong- in the air, not on the ground due to unnecessary product failures."

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.
Those interested in additional information about the Simriz 498 material can visit the Simrit booth (hall 3, stand B3) at the Farnborough International Airshow in England from July 14 to 20.

The Simrit Division is based at Freudenberg-NOK's headquarters in Plymouth, Mich. and is part of the Freudenberg and NOK Group, which has total annual sales of more than $12 billion. Simrit offers an extensive portfolio of sealing solutions for the aerospace, appliance, diesel engine, industrial, marine, off-highway equipment, oil and gas, recreational vehicle and semiconductor markets.

For more information, visit the Simrit website at


Adriana Ferrari

Bianchi Public Relations


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