Selex Zero Leakage Gasket
Zero leakage gasket is composed of stainless steel fixed inner and outer rings as well as industrial grade and nuclear grade flexible graphite sealing rings which are specialized making. The composed gaskets have much better mechanical intensity, compressibility and recovery rate, stress relaxation and low bolt loading can reach to ZEROleakage rate which is [≤ 1x10-7PaM 3/s(He)], because of we exploit the material of flexible graphite with outstanding flexibility, chemical resistant, heat resistant, flame resistant and radiation resistant. Our idea of creative design conforms to occasions which with sudden change of temperature and fluctuation pressure. Therefore, "ZERO" leakage gaskets provide the most effective sealing, the most reliable operation and the largest security assurances for middle and high pressure, high temperature or (and) fluctuation temperature, containers with nuclear safety level, equipments, valves, piping flange connecting.
Normal Pressure: PN≤ 420 or Class≤ 2500;
Normal Diameter: DN≤ 600 or NPS≤ 24;
Nominal Thickness: 4.4, 6.6, 10mm and so on;
Applicable Temperature: ≤ 450oC(air-like oxidizing medium); ≤ 650oC(steam)
Applicable Medium: Cooling water, steam, boric acid, air, nitrogen, demineralized water, oil, oxygen, 30% sodium hydroxide solution, and 7% nitric acid solution.
Sealing Capability: ≤ 1x10-7PaM 3/s
Perfect radiation resistant and chemical corrosion resistant (PHO-12)
Standard Dimension: Conform to GB, ASME, EN, JIS and HG standards as well as the dimension of non-standard raised flange, tongue and groove flange or groove flange.
The packing rings are made of GRAFSEAL high purity flexible graphite and both chemical composition and mechanical performance are in compliance with the nuclear grade requirements.
Both inner and outer fixed rings are made of 304 and 316L austenitic stainless steel and they are in compliance with the stipulations which are under the standards of GB, ANSI, ASTM and EN.
PRINCIPLE OF DESIGN
SELEX zero leakage gasket is designed on the principle of metal-to-metal contact (MMC), in which, both inner ring and outer ring or one of both rings is used as spacing ring. Therefore, under a given bolt preloading, the metal-to-metal contact between the top and bottom metallic flanges is realized (Fig. 1). The gaskets are more suitable to the occasion with fluctuation emperature and pressure. So, SELEX zero leakage gaskets provide more reliable sealing and safety assurance for flanges connection. This is the reason why SELEX zero leakage gaskets can be application to some harsh operation conditions in industrial installations and thermal power plant. Especially, they can be used in the nuclear power plant with high temperature steam-water piping.