Therban, the robust and heat-resistant hydrogenated nitrile rubber (HNBR) from specialty chemicals company LANXESS, is helping improve the reliability and lengthen the service life of the new flat gaskets from Klinger GmbH, Idstein, a leading provider of static sealing materials. According to Klinger, the new asbestos-free Quantum gasket is the first fiber-reinforced product of its kind to be exclusively HNBR-bound. This means that users can now harness the full potential of the synthetic rubber Therban – especially its media- and aging resistance – for demanding applications involving flat gaskets in industrial environments. According to Klinger, exacting aging tests confirm that Quantum flat gaskets are much more flexible than gaskets made of other fiber-reinforced sealing materials.
Flat gaskets are extremely important for the (petro-) chemical industry. They ensure, for instance, that chemicals and media that could be potentially harmful to the environment remain safely in the pipes for transportation. They also ensure the smooth operation of complex production plants that often feature several kilometers of flange-connected pipes. The sealing materials used for these joints must comply with strict technical standards – for instance, they must be able to withstand exposure to hot steam over extended periods without becoming prematurely brittle. The pressure variations usually encountered in steam pipes would otherwise damage the sealing material. “A flexible gasket capable of withstanding considerable expansion without fracturing is essential for a reliable sealing joint,” said Wolfgang Abt, product manager at Klinger. However, achieving this cost-effectively at high temperatures pushes the limits of even the most state-of-the-art synthetic rubber.
Klinger’s previous top product for use under particularly tough conditions was made of the robust hydrogenated nitrile rubber Therban from LANXESS, which is ideal for demanding sealing applications, due partly to its media- and heat resistance. For technical reasons, however, the predecessors to the current Quantum product range still had a core layer made of nitrile rubber (NBR). This affected the service life of the gaskets, since NBR, like all unsaturated rubbers, ages under high temperatures and gradually becomes brittle.
When developing the new fiber-reinforced Quantum gaskets, Klinger engineers were able to dispense with the NBR component. “The fillers and fibers in the new gaskets are bound exclusively with Therban. This significantly lengthens the service life of the products at high temperatures,” said Abt. “Compared with existing fiber-reinforced sealing materials, it offers a whole new level of flexibility at constantly high temperatures – while also offering better chemical resistance and a wider range of applications than any other fiber-reinforced sealing material,” he added.
To check the material’s aging resistance under demanding operational conditions, Klinger subjected the Therban-bound sealing material to a three-point bending stress test (ISO 178) after storing it at high temperatures. The result confirmed that, “even after 600 hours of exposure to temperatures of 200 °C, Klinger Quantum is around eight times more flexible than any other fiber-reinforced sealing material – thanks in part to Therban,” said Abt. The material also performs well in other tests relevant to sealing applications – for instance, the gasket factor QSmax to EN 13555 or tightness under operating conditions at high temperatures (QSmin ). Its reliability and long service life therefore make it perfect for use in hot steam pipes. Thanks to the special molecular structure of the hydrogenated nitrile rubber from LANXESS, the Quantum flat gasket is also suitable for use in oils, water, steam, gases, salt solutions, fuels, alcohols, weak organic and inorganic acids, hydrocarbons, lubricants and refrigerants. “The asbestos-free sealing material used for our Quantum flat gaskets therefore meets the very highest performance standards,” said Abt.
LANXESS (lanxess.com) is a leading specialty chemicals company with sales of EUR 5.06 billion in 2009 and currently around 14,700 employees in 24 countries. The company is represented at 45 production sites worldwide. The core business of LANXESS is the development, manufacturing and marketing of plastics, rubber, intermediates and specialty chemicals.
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