Flexible graphite/metal multilayer gaskets suited to high-temperature service conditions

A composite plate comprising an alternating stack of at least 3 flexible graphite foils and at least 2 perforated metal reinforcing foils with spurs, such that a first and a last foil of said alternating stack comprise flexible graphite foils, wherein

• the thicknesses of each of said flexible graphite foils is the same or different, wherein any 2 mm slice of thickness of the composite plate (i) comprises at least 3 layers of flexible graphite, and (ii) has a density per unit area of not more than 2.34 kg/m2 and
• for each of said perforated metal reinforcing foils, the spurs present on said foil have a height in relation to the surface of said foil that does not exceed about 1.3 times the thickness of the thinnest flexible graphite layer to which said foil is attached and
• wherein said plate is capable of producing a ring gasket that has a thickness of 2 mm, an outside diameter of 92 mm and an inside diameter of 49 mm with creep resistance up to a bearing pressure on the gasket of at least 200 MPa and a leakage rate of not more than 10−4 mb*1/s*m (measured with a gasket/flange assembly at a helium pressure inside the flanges of 1 bar) as determined under the following conditions:
• clamping between standard E DN40/PN40 shaped flanges in accordance with DIN 2635;
• external pressure exerted on the faces of the gasket:
• 30 MPa;
• temperature cycling of the gasket/flange assembly:
• once between 25° C. and 300° C.;
• held at 300° C. for 48 hrs.
• measurement of the mechanical strength QSmax according to the standard EN 13555.