Hi,
just to expand on PVRV's post. The tubeside would be defined as those compartments which contain (or are in contact with) the tubeside process fluid.It includes channel (or bonnet), tubes, nozzles, & flanges connected to these parts.The shellside would be those compartments that contain (or are in contact with) the shellside fluid .It includes the cylindrical shell, the shell cover, any nozzles, & flanges connected to these parts.Items like the tubesheets, floating head assembly, and tubes, are part of both the shellside and tubeside as they are in contact with both tubeside and shellside process fluids.
John