Carbon Steel Construction

U-Tube Heat Exchangers For

Carbon Steel Construction
U-Tube Duty

Carbon steel is the cost benchmark against which every alloy decision is measured. It does not resist corrosion, it tolerates it, and the design accounts for that with a stated allowance.

SA-516 Grade 70 plate for shells and tubesheets, with SA-179 or SA-214 tube, covers an enormous amount of industrial heat exchanger work. The material is available, weldable, well understood and inexpensive.

Corrosion allowance. Rather than resisting attack, carbon steel construction adds thickness that is expected to be consumed over the design life. An eighth of an inch is a common allowance; more where the service warrants it.

Mixed Construction Economics. Putting a stainless or high-alloy bundle inside a carbon steel shell is routine, and it puts the expensive material where the aggressive fluid is rather than throughout the exchanger.

Watch two details. Galvanic pairing where dissimilar metals meet in a wetted joint, and differential thermal expansion between shell and bundle. A U-tube bundle handles the second by design, which is one more reason the geometry suits mixed construction.