THE PROBLEM
The existing polyurea tank lining had completely failed as a result of incorrect application. This meant that the anaerobic digester tank was no longer gas tight, resulting in reduced profitability for the operator.
SOLUTION
Initially we mechanically removed the polyurea tank lining in order to expose the concrete beneath.
Following removal of the existing tank lining all concrete surfaces were prepared by method of abrasive blasting in order to remove any remnants of the previous primer, clean the concrete and provide a mechanical key for the new tank lining.
All panel intersections and joints were primed using a damp tolerant epoxy primer to ensure excellent adhesion of the subsequent polyurea coating. The roof panel intersections were bridged using a bond breaker tape and the wall to wall joints sealed using a polyurethane jointing compound.
Applying the SPI Corrolastic UB pure polyurea
The gas space was then sealed by the application of SPI Corrolastic UB pure polyurea to a thickness of 2mm.
Protecting The Concrete Surfaces
To protect all concrete surfaces Remmers Epoxy Universal was then applied to a thickness of 1000 microns in multiple coats. This tank lining material has extensive case histories going back over 20 years protecting anaerobic digester tanks. Remmers Epoxy Universal can crack bridge to 0.2mm, which exceeds the design crack width of the concrete used.
As part of our standard tank lining quality assurance the new tank lining was checked for porosity using DC holiday spark testers. Any pin holes found were marked prior to touching in using the same material.
This tank lining was warranted for 10 years from completion.
