Heat Exchanger Water Box Protection

The challenge

In refinery cooling-water service, a shell-and-tube exchanger water box and tube sheet take constant chemical and erosive attack. The metal thins, and corrosion concentrates at the tube-to-tubesheet interface where galvanic attack can take hold. Left unchecked, this loss of wall threatens the integrity of the exchanger and forces unplanned repairs. That pulls a unit out of the cooling train and shortens the interval between turnarounds.

The Belzona approach

The water box and tube sheet internals are blasted back to clean, sound metal. Belzona 1000 Series composites rebuild the lost and eroded sections to restore the original profile. Then a Belzona 5000 Series barrier coating system goes across the internals to separate the metal from the cooling water. Where the exchanger runs cathodic protection, the coating is integrated with the existing system so the two work together.

1. Assess and isolateThe water box and tube sheet are inspected, the metal loss is mapped, and the unit is confirmed isolated and ready for in-situ or shop work.
2. Surface preparationAbrasive blasting takes the internals to a clean, anchored profile and removes corrosion product from around the tube ends.
3. Rebuild lost metal1000 Series composites rebuild eroded and thinned areas to bring the surface back to profile.
4. Apply barrier coatingThe water box and tube sheet are coated with a 5000 Series protective system, tied into any existing cathodic protection.
5. Cure and return to serviceCure and coating continuity are confirmed, then the exchanger goes back for reassembly and return to the cooling train.