Varies depending on code requirements and TEMA class, so a combination of the two. It does an estimated weight calculation which is detailed in the design manual, which I assume is used for the location of the saddles.
HTRI is not a mechanical design program. HTRI program is focused on the thermal and hydraulic modeling of heat exchangers. HTRI does not have the option for seismic and/or wind loading. Saddles are not "designed" in the program and the estimated saddle locations is just that, an estimation. HTRI attempts to locate the saddles with adequate clearance to the process nozzles, but that also can be incorrect if the nozzles require reinforcement pads, since HTRI does not model/calculate nozzle design on the shell.
