A tube bundle-type heat exchanger, to a tube base, and to a method for sealing same. Aspects of the invention relate to a tube base for a tube bundle-type heat exchanger. In particular, the tube base includes a stack of multiple tube base plates with at least one through-opening for receiving a respective tube of the tube bundle-type heat exchanger. The throughopening is sealed by at least one seal ring. Additional aspects relate to a tube bundle-type heat exchanger comprising such a tube base and to a method for sealing a tube bundle-type heat exchanger in particular in the region of the tube base.