Our client contacted us regarding a cold water storage tank that required an urgent unplanned lining due to delays in the delivery of a new tank. With the hotel opening in two weeks from the enquiry a fast turnaround was required.
Visiting site the following day from the enquiry we put together a proposal to remove the existing failing bitumen coating prior to the application of a fast curing WRAS approved polyurethane in the form of Acothane.
Initially the existing lining and corrosion were removed using needle guns, chipping hammers and tungsten carbide scrapers. A final light wire brush and abrasion to raise a surface profile were undertaken using orbital sanders. Care was taken not to polish the steels surface of the tank which would have been detrimental to the adhesion of the new tank lining.
From our 25 years experience relining tanks such as this we knew that it would be highly probable that perforations in the tank’s structure would be present following the preparation works. We were prepared for such eventualities and plated the two perforations present using galvanised steel plate bonded using a drinking water approved epoxy adhesive.
Tank Lining process
Once the tank had been prepared and repaired a heavy stripe coat of Acothane was applied to all angles and edges to ensure full coating film build. This is good practice as part of a tank lining process as paint pulls thin on corners and welds due to gravity and surface tension. By applying an additional stripe coat with each coat the full thickness of the tank lining is achieved in these critical areas.
This was followed by the application of the full coat and subsequent second stripe and full coats. As per good tank lining practice these were applied in contrasting colour to aid with identification of application.
The tank lining was applied to a thickness of 1000 microns and tested for porosity using a DC holiday spark tester.