The new food waste reception tank at the anaerobic digestion site required a tank lining.
We had previously applied tank linings to four tanks on site which were still performing well. We therefore proposed the application of the same tank lining system.
The first part of this tank lining project was to seal the tank externally. The joints between the tank panels were prepared by method of high pressure spinning jet, prior to priming and sealing using a polyurethane jointing compound.
Once weatherproof the tank internals were prepared by method of high pressure spinning jet in order to remove surface laitance and contaminants. As with all tank linings good preparation is essential to ensure adhesion of the new tank lining.
The tank was then allowed to dry by means of indirect oil fired heating in order to ensure the moisture content of the concrete was within the parameters set by the tank lining manufacturer.
All joints in the tank were primed using Remmers Epoxy MT100 damp tolerant epoxy primer.
The vertical joints were sealed using a polyurethane jointing compound, and the roof joints bridged using a aluminium bond breaker tape. To these areas SPI Corrolastic HT pure polyurea was applied by method of heated plural component spray unit to a thickness of 2mm. This material can elongate close to 400 %, providing a gas tight seal that also offers excellent chemical resistance.
The next stage of the tank lining process was to apply Remmers Epoxy Universal throughout the tank by method of airless spray. This flexible epoxy tank lining material can crack bridge to 0.2mm – a standard crack design width for concrete. This tank lining material has extensive case histories in the anaerobic digestion industry going back nearly 20 years.
The lining was applied in two coats of contrasting colour to ensure full coverage.
Where required a thickened version was made using Thixorope and applied by filling blade to fill blow holes in the concrete. It is essential that these are fully sealed to ensure a seamless finish.
Testing the tank lining quality
As part of our standard tank lining quality assurance the lining was checked for pin holing by method of spark testing. A single pin hole is a point of failure through which aggressive chemicals and gases can enter the concrete.
We warranted this tank lining for 10 years from completion.