Another tank reline as a result of an incorrectly applied polyurea coating to this concrete storage tank which is used as an anaerobic digester. The existing polyurea tank lining had been applied to a primer which had exceeding its re-coating window, meaning that it was poorly adhered and de-bonding from the surface of the concrete storage tank.
Following the removal of the failed polyurea tank lining by others we prepared the concrete storage tank internals by method of abrasive blasting to remove any remaining epoxy primer. Correct preparation is the cornerstone of any tank reline, something many less experienced tank lining contractors often fail to appreciate.
As important as correct preparation when undertaking a tank reline is surface cleanliness. If your new tank lining is adhered to dust rather than the concrete storage tank itself it will not perform as expected.
Cleaning using high pressure washing
To ensure the excellent adhesion of our tank lining all surfaces were cleaned by method of high pressure washing following the clearing of the spent blasting abrasive and arisings.
When undertaking a concrete storage tank reline ensuring the correct substrate conditions with regard to humidity is very important. We utilized the existing tank heating to dry the concrete to a point where the moisture in the substrate was below the 6% required for our tank lining specification.
Priming the joints using Remmers Epoxy MT100
To create a gas tight seal required for the anaerobic digester the joints between the roof panels and the wall to wall joints was first primed using Remmers Epoxy MT100 damp tolerant epoxy primer. Once cured the roof to roof joints were bridged using an Aluminium bond breaker tape. The wall to wall joints were then sealed using Remmers PU AW – a polyurethane jointing compound specifically designed for such applications.
All previously sealed areas were then made gas tight by the spray application of Specialty Products Incorporated Corrolastic UB pure polyurea. This material contains their patented ultra-bond technology that overcomes the traditional challenges of applying polyurea tank linings that we suspect caused the failure of the original tank lining.
Following the making of the tank gas tight Remmers Epoxy universal was applied to a thickness of 1000 micrometers by method of airless spray.
To ensure that the tank reline was free from pin holes and defects the tank lining was spark tested and where defects were found these were touched in using the same material.