U-Tube Compared to Other Designs

Two questions settle most shell and tube selections. Does the tube side need mechanical cleaning? Does the design need to accommodate large or cycling thermal expansion? Answer both and the rear head chooses itself. Fixed tubesheet where neither applies, U-tube where expansion matters and the tube side is clean, floating head where both apply. Plate and frame is a separate conversation about approach temperature and footprint.

• Versus fixed tubesheet. Fixed is cheaper and lets you rod the tubes end to end. It cannot clean the shell side mechanically and needs an expansion joint at large differential temperature.
• Versus floating head. Both remove the bundle and both absorb expansion. Floating head lets you clean the tube side; U-tube costs less and has fewer sealed joints at pressure.

• Versus straight tube. One tubesheet and one head instead of two is the cost argument. Against it: no rodding through the bend, and pass count must be even.
• Versus plate and frame. Plate wins on close approach and footprint in clean liquid duty. U-tube wins on pressure, temperature, viscosity, particulates and steam.

• The disqualifying condition. A fouling tube-side stream. If the fluid that scales has to run inside the tubes, choose something you can rod.
• The deciding condition. Thermal cycling. Nothing else in the shell and tube family handles repeated large temperature swings as simply.