A welding method for making cladding or buttering on an inner surface of a base material, an inner surface of an opening portion formed in the base material, and the cut surface formed in such a manner that the cut surface is continuous from the inner surface of the base material to the inner surface of the opening portion, wherein the welding method includes a step of forming a protruding portion on the base material in advance, the protruding portion including a temporary welding surface extending toward the center of the opening portion in such a manner that the temporary welding surface is uniformly continuous to the inner surface of the base material and including the cut surface buried therein.

A means of offsetting semi-circular tube support plates typically present in heat exchangers with cross flow baffles, such as axial flow economizers, utilizing the motive force of steam generator pressurization. The offset slightly flexes the tubes, thereby providing a preload which minimizes the potential for tube vibration and wear.

A tube and shell steam generator having an anti-clogging heat exchange tube bundle wherein the tube support plates within the tube bundle are designed with varying degrees of porosity thereby regulating local secondary side fluid conditions (velocity, quality, superheat, void fraction, etc.) in a manner to reduce the potential for clogging of the tube support plate lobes that are more prone to clogging.

A tube expansion method of mounting a drain tube as tube member by insertion and expansion to a through hole in which opening portions at both ends are obliquely formed, the method including: inserting the drain tube to the through hole so that the end portions protrude from the opening portions at both ends of the through hole; inserting a tube expander into the drain tube to expand the drain tube up to a predetermined inner diameter while moving the tube expander to the other end portion from one end portion of the drain tube; cutting each end portion of the tube member protruding from each opening portion of the through hole along an oblique shape of each opening portion; and welding the cut end portion of the drain tube and the opening portion of the through hole.

A tube and shell steam generator in which a series of rods having a diameter substantially equal to that of the heat exchange tubing in the tube bundle are placed on either side of the tube lane to buffer the flow in the tube lane from the heat exchange tubes to attenuate turbulent forces on the first several rows of heat exchange tubes adjacent to the tube lane.