THE PROBLEM
The new concrete effluent tank required a protective tank lining in order to protect the concrete from attack from hydrogen sulphide and biogenic sulphuric acid.
SOLUTION
To ensure excellent adhesion of the new tank lining all surfaces were prepared by method of abrasive blasting to remove surface laitance and contaminants.
Ensuring optimum tank adhesion
Following clearing of spent blast abrasive all surfaces were washed down to ensure optimum adhesion of the new tank lining.
To fill blow holes in the concrete a cementitious fairing coat was applied to all surfaces to be coated. This is very important when lining concrete tanks as it is not possible to fill blow holes with paint alone.
Priming the tank
Following cure and hydration of the fairing coat the tank was primed using a damp tolerant epoxy primer. Prior to this the moisture content of the concrete was checked to ensure compliance with the manufacturers recommendations.
The primer was applied in two coats to ensure the surface was fully sealed prior to the application of the polyurea tank lining. The exothermic nature of polyurea means that if the surface is not properly sealed excessive pin holing can be experienced.
All corners were rounded using a polyurethane jointing compound and an anchor rebate for the polyurea tank lining cut using vacuum controlled diamond saws.
Lining the tank with polyurea
Once satisfied with the preparation and priming works the tank was lined using SPI Corrolastic UB pure polyurea. The tank lining was applied to thickness of 2mm.
This material can elongate over 400%, meaning any future cracking in the structure should be accommodated without splitting of the tank lining. This tank lining material also has an expected service life in excess of 20 years until first maintenance.
As part of our standard quality assurance the lining was checked for pin holing using a DC holiday spark tester. Any defects found were marked prior to touching in using the same material.
We warranted this tank lining for 10 years from completion.
