A structural framework for supporting the heat exchanger of a steam generator, the former being comprised of serpentine tubes having sloped segments to facilitate the drainage of water from the heat exchanger when the steam generator is shutdown. The structural framework includes paired groups of vertically and diagonally extending first support members contiguously straddling the sloped-tube segments. The paired first support members are rigidly connected by second support members which extend between adjacent sloped-tube segments. The structural framework preserves the spacing between the sloped-tube segments and prevents direct contact between adjoining tube surfaces, but is not attached to the straddled tube segments and, thus, provides a tube supporting fit that is loose enough to permit the tubes to move freely due to expansion and contraction at different rates from that of the structural framework.