Abstract: A shell and tube heat exchanger (2) having a vertical dam (50) surrounding one of the steam-water separators (26a), so as to create a low flow velocity or quiescent area where solids will settle out. The dam encircles an area seven times greater than the average area per-separator throughout the rest of separating deck, so that there is a low flow velocity. Also, an orifice (52) is positioned in the inlet to the dammed in separator, to further reduce the flow velocity. The settled out solids are removed from the steam generator through a blowdown pipe (60).

Abstract: In combination, a vessel (10), opening means (16) in the vessel, a cover (18), flange means (20) surrounding the opening means, a primary closing means (22, 24) for the cover including a plurality of studs (22) securing the cover onto the vessel, the studs having inner ends threaded into openings (26) in the vessel, nuts (24) cooperating with the outer ends of each of the studs, secondary closing means (32, 34, 38, 40) for the cover including cylindrical clamp means (30, 32) made up of more than one piece, a protruding ledge (34) on the cover over which the clamp means extends, an annular groove (36) in the flange means into which the clamp means extends, a circular retaining ring (38) which surrounds the clamp means, a plurality of threaded openings (42) in the retaining ring, and a plurality of set screws (40) threaded into the openings, so that their ends force the clamp means into tight clamping engagement with the ledge on the cover and the groove in the flange means.