Case Studies

Nuclear Plant Waterbox Rebuild

PROBLEM

By 1983, at a New England utility, the cast iron waterboxes, were subjected to many years of salt water attack. The corrosion was almost to the failure point, and the waterboxes were leaking at a few points. Replacement of the old waterboxes, even if possible, would take from 1.5 to 2 years to have them fabricated. Welding was not considered as the heat stress might cause cracking and complete failure of the waterboxes and shutdown of the plant.

SOLUTION

DUROMAR, INC. was contracted to rebuild the surface using our thick film, permeation and abrasion resistant epoxy lining, SAR. After completely removing the thick crust of scale and digging out the graphitized pits, the surface was steamed to remove chlorides, dried and sandblasted to near-white metal. The rough surface was reprofiled with SAR which in some areas required over 1″ of material. Then the complete surface was covered with a minimum film thickness of 80 mils DFT. To decrease drag and improve impact resistance, a topcoat of EAC @ 40 mils DFT was applied.

RESULTS

The DUROMAR lining of approximately 120 mils of heavily filled, SAR and EAC, was found to add considerable strength to the now thinned cast iron surfaces. It has been shown that at this thickness, 1/3 to 1/2 the original strength can be added back to the lined surface. The work was performed during a normal outage time period and the waterboxes were put back into service with no additional downtime. The system was stable and leak free.

CURRENT STATUS

The plant was decommissioned in 1993, but the rebuilt waterboxes performed perfectly during this period with no leaking or lost generation due to waterbox problems.

COMMENTS

As with all DUROMAR products, the SAR and EAC are 100% solids, Zero VOC, solvent free, and contain no carcinogens or heavy metals. This makes application easy and safe for both the applicators and the environment. This process has also been successfully used to line carbon steel waterboxes with similar excellent long term results.

Case History-011153