A metallic flange connection gasket to be located between opposite attractable flanges ( 1;2), the gasket on each of opposite faces thereof exhibiting at least one protruding, circling first ridge ( 8; 8 '), and at least one first valley ( 9; 9') being adjacent the first ridge ( 8; 8') characterized in - that the gasket has: - a radially outer portion with a first thickness, - a first, radially inner portion radially inwards of the outer portion, and - a second, radially inner portion radially inwards of the first inner portion, the inner portions ( 6; 7) both exhibiting a second thickness being larger than the first thickness, - that said at least one circling first ridge ( 8; 8') and said at least one adjacent first valley ( 9; 9 ') are located at a region associated with at least one of said inner portions ( 6; 7), - that axially opposite located first ridges ( 8; 8 '), i.e. on face of either side of the gasket, have in non-depressed state a first peak-to-peak distance, and have in a depressed state with the flanges ( 1; 2) pulled or attracted towards each other and with the gasket thereby in a flange sealing function, a second and smaller peak-to-peak distance, the first distance being larger than the second peak-to-peak distance, and the second thickness being smaller than the first distance and said second distance, - that the gasket on both opposite side faces thereof: - radially outside the first ridge ( 8; 8 ') is configured with a second ridge to form a first recess ( 10 ') between said first and second ridges, and - radially inside the first ridge ( 8; 8') is configured with a third ridge to form a second recess ( 11 ') between said first and third ridges, wherein the axially opposite located second and third ridges (1 0; 11), i.e. on face on either side of the gasket, have in non-depressed state said first peak-to-peak distance, and wherein the first ridge ( 8; 8 ') constitutes a primary seal and the second and third ridges ( 10; 11) constitute respective secondary seals. - that the gasket has: - a radially outer portion with a first thickness, - a first, radially inner portion radially inwards of the outer portion, and - a second, radially inner portion radially inwards of the first inner portion, the inner portions ( 6; 7) both exhibiting a second thickness being larger than the first thickness, - a radially outer portion with a first thickness, - a first, radially inner portion radially inwards of the outer portion, and - a second, radially inner portion radially inwards of the first inner portion, the inner portions ( 6; 7) both exhibiting a second thickness being larger than the first thickness, - that said at least one circling first ridge ( 8; 8') and said at least one adjacent first valley ( 9; 9 ') are located at a region associated with at least one of said inner portions ( 6; 7), - that axially opposite located first ridges ( 8; 8 '), i.e. on face of either side of the gasket, have in non-depressed state a first peak-to-peak distance, and have in a depressed state with the flanges ( 1; 2) pulled or attracted towards each other and with the gasket thereby in a flange sealing function, a second and smaller peak-to-peak distance, the first distance being larger than the second peak-to-peak distance, and the second thickness being smaller than the first distance and said second distance, - that the gasket on both opposite side faces thereof: - radially outside the first ridge ( 8; 8 ') is configured with a second ridge to form a first recess ( 10 ') between said first and second ridges, and - radially inside the first ridge ( 8; 8') is configured with a third ridge to form a second recess ( 11 ') between said first and third ridges, - radially outside the first ridge ( 8; 8 ') is configured with a second ridge to form a first recess ( 10 ') between said first and second ridges, and - radially inside the first ridge ( 8; 8') is configured with a third ridge to form a second recess ( 11 ') between said first and third ridges,