Higher demands from the chemical and petrochemical industries require even better sealing materials: materials that are not only able to help resist a multitude of aggressive chemicals, high pressures and extremes of temperatures, but that can also withstand abrupt drops in pressure and help facilitate the reliable operation of equipment even at extremely low temperatures. Therefore, DuPont has introduced Kalrez perfluoroelastomer components, with improved rapid gas decompression (RGD) resistance and low temperature capabilities.
Johan François
Dwindling oil and gas reserves require the exploitation of new sources, some of which are to be found, for example, deep under the ocean floor. Not only do such environments bring with them very high temperatures and levels of pressure, but also an increased potential for rapid gas decompression (RGD). Moreover, the equipment and materials used at such depths are exposed to high concentrations of aggressive gases, such as carbon dioxide, methane, hydrogen sulphide, steam, ammonia and other corrosive amine-based substances.
Hydrogenated Nitrile Butadiene Rubber (HNBR) is still widely used as a sealing material for oil and gas extraction equipment, because of its excellent resistance to RGD. However, higher operating temperatures have resulted in the increased use of fluoroelastomer (FKM) type materials, which are specifically compounded for resistance to rapid gas decompression. Higher concentrations of aggressive gases such as hydrogen sulphide have also resulted in the use of perfluoroelastomers (FFKM). Currently available, traditional FFKM grades with rapid gas decompression resistance exhibit less robust mechanical properties than HNBR, and may therefore not be sufficiently resistant to RGD.
DuPont has now introduced Kalrez 0090 perfluoroelastomer components. This compound offers improved resistance to rapid gas decompression and, at the same time, provides the combination of benefits typical of FFKM, including very high chemical and temperature resistance, minimal volume swell and low compression set performance. In tests for RGD resistance, conducted by the Materials Engineering Research Laboratory (MERL) in Great Britain, Kalrez 0090 was given the highest 0000 rating according to the Norsok M-710 stand-ard. This standard was developed by the Norwegian oil and gas industry, and specifies the requirements for sealing materials intended for use in oil and gas equipment.
Resistance down to -42 °C
The sub-zero climate often found at the surface of oil and gas production plants in northern Europe or the Arctic require that the materials used there are sufficiently resistant to such low temperatures. Normally, when exposed to extremely low temperatures, elastomers tend to become glass-like and very brittle, thereby limiting their sealing performance.
In laboratory tests and field reports, the latest Kalrez Spectrum 0040 perfluoroelastomer components from DuPont exhibit a low temperature resistance of down to -42 °C in static seal applications. The resistance to chemicals such as acids, amines, bases, aldehydes and ethylene oxides, as well as hot water and steam, is similar to other products from the Kalrez Spectrum family.
Kalrez Spectrum 0040 sealing products offer the potential for use in a range of applications in chemical and petrochemical equipment, as well as in the ship building, rail and automotive industries – all of which can involve very low temperatures.
An extended use of FFKM
Kalrez perfluoroelastomer parts have been commercially available for more than 30 years and are used in applications that demand high resistance to the effects of chemicals and extreme temperatures. If selected correctly, they can help significantly extend the lifetime of equipment used in the chemical and petrochemical industries and can thus offer the potential for vast savings in the long term. The two new Kalrez grades can substantially extend the potential use of perfluoroelastomers.
Online-Info www.cpp-net.com/2310405
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