Polyurea Water Tank Lining
The leaking tanks existing butyl tank liner had split and was allowing water egress. This was preventing the water storage tank from being used for emergency fire fighting water.
We recommended the application of a spray applied polyurea tank lining as the best solution. Polyurea is an excellent water tank lining coating for sectional tanks such as these due to its flexibility and elongation properties. This means that the polyurea tank lining will not split or crack when the tank is emptied and filled – sometimes rapidly in the case of these tanks.
Polyurea tank linings are no different to other coatings in that correct preparation is essential to ensure the long service life of the water tank lining. Following the removal of the existing tank liners the tanks internals were prepared by method of abrasive blasting to both clean and raise surface profile on the galvanized sectional tank panels. This ensured excellent adhesion of the new polyurea tank linings.
Double priming with Epoxy Resin
Once prepared the tank floors were double primed using a damp tolerant epoxy resin. The purpose of this was two fold. Firstly fully sealing the concrete tanks bases to prevent pin holing and out gassing in the polyurea coating. Secondly by applying two coats of epoxy this formed a liquid damp proof membrane, preventing potential moisture drive and subsequent blistering.
A fillet detail was then installed at the tanks floor/wall interface to isolate this potential point of movement from the polyurea lining as per good practice.
Some of the bolt heads internal to the tanks were protruding from the sectional panels. This would create cavities which would be difficult to fully seal with polyurea due to its fast gel time. To resolve this and ensure a seamless polyurea lining these areas were detailed using a polyurethane mastic.
Spray applying pure polyurea
Finally Specialty Products Incorporated Watershield III was spray applied to a thickness of 2mm throughout both tanks. This ultra flexible pure polyurea was specified due to its ability to elongate in excess of 900%, giving significantly increased flexibility.
The new polyurea tank linings were spark tested to ensure that they were free from pin holes and defects. Where found these were marked with chalk prior to touching in using the same material.
Seamless finish with polyurethane jointing compound
Finally the termination detail at the top of the tanks was sealed using a polyurethane jointing compound to ensure a seamless finish.