A new post on the MGT Blog at http://syokell.blogspot.com/ discusses hydrostatic testing heat exchangers, with emphasis on testing when leaks are not visible as in fixed tubesheet designs and typical closed feedwater heater construction. It discusses weeping from the channel side to the shell side and points out that the gages customarily used in heat exchanger shops to determine whether there is leakage from the channel to the shell through the tube-to-tubesheet joints by pressure loss are inadequate for indicating weeping. The post on the blog poses questions about the ASME Code’s requirements and suggests cautions that Users, Designers and Manufacturers should take for constructions in which leakage is not visible.