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.

Our approach

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

1. Assess and isolateWe inspect the water box and tube sheet, map the metal loss, and confirm the unit is isolated and ready for in-situ or shop work.
2. Surface preparationWe abrasive blast the internals to a clean, anchored profile and remove corrosion product from around the tube ends.
3. Rebuild lost metalWe rebuild eroded and thinned areas with 1000 Series composites to bring the surface back to profile.
4. Apply barrier coatingWe coat the water box and tube sheet with a 5000 Series protective system and tie it into any existing cathodic protection.
5. Cure and return to serviceWe confirm cure and coating continuity, then hand the exchanger back for reassembly and return to the cooling train.