How is thermal expansion addressed in shell-and-tube heat exchanger design?

Differential thermal expansion between shell and tubes (different temperatures and/or materials) creates stress. Solutions include: Fixed tubesheet with expansion joint in shell (allows relative movement), U-tube bundle (tubes expand freely), Floating head designs (one tubesheet moves freely), and using same material for shell and tubes when possible. For severe cases, packed floating head or pull-through floating head designs are used. Expansion calculations per TEMA/ASME determine if accommodation is needed based on differential growth and allowable stress.