42 are important care must be taken that flattening or wrinkling of the tube 28 does not occur which could increase the pressure drop in the tube harbor unwanted contaminants and create difficulty in cleaning the tube 28 moreover deformation could adversely affect the flow pattern within the tube 28 in turn adversely affecting the heat transfer chart i______________________________________maximum tube wall thicknesstube o d maximum wall thickness______________________________________1 4 1 2 in 0 83 in 3 4 1 in 120 in 11 4 11 2 in 200 in 2 21 2 in 218 in 3 4 in 300 in ______________________________________ baffles 40 are located within the shell 10 the baffles 40 extend the entire width of the enclosed compartment 12 substantially transverse of the coils 42 of the tube 28 in a preferred embodiment the baffles 40 are not attached to the shell 10 or the coils 42 the baffles 40 are held in position by their interaction with the coils 42 and with an anti rotation bar 43 specifically a notch 45 in the baffle 40 fits about the anti rotation bar 41 keeping the baffle 40 from rotating and the coils 42 keep the baffles 40 from moving laterally such an arrangement allows for easy removal and disassembly for repair individual baffles 40 are shown in fig2 each baffle 40 defines a port 44 that allows fluid within the enclosed compartment 12 to flow from one baffle 40 to the next the baffles 40 are arranged so that.