Mighty Therm, Cupronickel Tube Assembly, 3500I/3200E. LAARS Code Compliant ASME Tube Assemblies Built in accordance w/the requirements of the ASME Boiler and Pressure Vessel Code. Cupronickel tubes w/glass-lined tubs, ideal for corrosive or softwater applications (under 7.5 grains hardness), or when hard water pumping creates higher tube velocities. Suitable for swimming pool heaters.