Diosynth: Waste Chemical Effluent Tank Lining

ManwayDiosynth (Akzo Nobel) had relined a concrete waste chemical collection sump some years ago but the lining had severely failed. The sump is used for the collection of waste chemicals, including solvents, Hcl and caustic with a range of 0 to 15ph. We were instructed to refurbish the lining tank to extend its operational use.

Challenges

  • The original internal lining had been almost completely eaten away.
  • Much of the concrete that formed the body of the sump had dissolved, exposing hard-core in several places.
  • In some areas, the severity of the attack was so severe, we found cavities in the wall of over 75mm deep.

Before treatment showing the extent of the chemical attack

Our Solution

As this tank had direct contact with harsh chemicals, we selected a vinyl ester based system with glass flake reinforcement. These materials have a proven track record for elevate temperature tolerance, chemical resistance and are suitable for use in aggressive tank lining environments.

To repair the substrate on the floors and walls of the sump we used a two-pack epoxy resin concrete repair system. The sump was high pressure jet washed and grit blasted using a medium grade abrasive. This removed any contamination and cleaned the surfaces to the required standard. The new lining system was applied using seven separate coating systems, including a moisture tolerant epoxy primer, an epoxy resin based concrete repair render system, a water based epoxy resin primer, three coats of a glass flake reinforced vinyl ester tank lining system and a final glass flake reinforced vinyl ester top coat. Each coat was applied in different colours to ensure correct wet film coverage. On completion, we tested the new lining for micro porosity and dry film thickness.

Following completion of our work



Results

The advantage of using an epoxy based concrete repair system was that the entire project could be completed in less than a week and the sump returned to active service immediately on completion. The sump with its new lining will now have an expected working life in excess of fifteen years.