Abstract: A gasket for sealing two flange faces against each other comprising at least two compressible layers, a reinforcing metal ring sandwiched between the compressible layers, said compressible layers and metal ring having a combined thickness and an inner and an outer edge, a resilient O-ring located at the inner edge of the combined compressible layers and metal ring, said O-ring having an inner edge and having a diameter greater than said combined thickness, and a fluoropolymer sheet enveloping the O-ring and combined compressible layers and metal ring to form the gasket such that when the gasket is installed the fluoropolymer sheet contacts both flange faces and covers the inner edge of the O-ring. The gasket is particularly suitable for sealing the surfaces of glass coated flanges where the contents of materials within the flanges are under pressure.