As part of our clients proactive water hygiene regime they had identified that the sectional fiberglass tanks were beginning to break down with the potential to harbour harmful bacteria such as legionella. The difficult access, disruption to production and cost meant that replacement was not a good solution.
We proposed the application of a seamless, flexible and WRAS approved tank lining as the best solution for ensuring the ongoing hygienic operation of these four tanks.
Initially all surfaces were prepared by method of vacuum controlled sanding to create an excellent mechanical profile for the new linings to adhere to. This was followed by the thorough vacuuming to ensure all surfaces where clean and dust free and ready to accept the new tank lining.
To ensure the correct climatic conditions for coating application at this point indirect heating was introduced and climatic monitoring put in place with regard to relative humidity and dew point. This is something less experienced contractors will often omit at their detriment with a high risk of tank lining failure through poor adhesion if climatic restraints are not observed.
Sealing with polyurethane jointing compound
All corners and seams in the tank were then sealed using a WRAS approved polyurethane jointing compound. Not only does this serve as a secondary seal, but it also serves to isolate the points of greatest potential movement from the new lining.
Our choice of tank lining material for these tanks was Spencer Coatings Acothane. This was selected for its flexibility, high film build, fast curing and WRAS approval. Using a flexible tank lining is key when lining section GRP tanks as the material inherently flexes during filling and emptying which would lead to cracking and debondment in brittle materials such as epoxy and fiberglass.
To ensure full film build of the lining separate stripe coats were applied at each stage of the coating cycle in contrasting colour as per best coating practice. Each coat was also applied in contrasting colour, at a dry film thickness of 500 microns per coat to achieve a total tank lining thickness of 1000 microns.