Tank valve and tank with such a valve

A tank valve, comprising:

• a valve seat comprising a first plate-shaped part, and a second ring shaped part;
• and
• a valve disc displaceable relative to the valve seat along a displacement direction to either a closed position where the tank valve is closed or to a through-flow position where the tank valve is open,
• wherein the valve disc comprises a first contact area, which is in contact with the first part of the valve seat when the tank valve is in the closed position, and
• wherein the valve disc comprises a second contact area, which is in contact with the second part of the valve seat when the tank valve is in the closed position.