Water Tank Relining by PH Water Technologies- A Cost Effective Solutions For Water Storage Tanks.
PH Water Technologies were recently contacted by a prestigious London Hotel to undertake the complete replacement of four very large galvanized steel cold water storage, which had suffered failure of the internal coating and led to widespread osmotic blistering and corrosion.
Urgent action was required as the Legionella Risk Assessment had identified that the tanks posed a significant risk to system users due to heavy corrosion, a nutrient for Legionella.
Our original brief was to cut out and remove the 4 large tanks located within the 10th & 25th floor plantrooms and replace with new GRP sectional tanks.
During our survey ph Water Technologies identified that the structural integrity of the old tanks were found to be sound and ideal for the application of a polyurethane lining system. At the following meeting we presented this alternative solution to the hotel management team highlighting some of the benefits.
- Significant financial savings.
- Minimal disruption to the operation of the hotel.
- No disruption to the hotels water services.
- Suitability for storing wholesome water.
- 10 year guarantee
The product recommended was a SOLVENT FREE DRINKING WATER POLYURETHANE (DWPU), which offers numerous economic, technical and environmental features and benefits, some of which are highlighted below:
- WRAS Approved
- Complete Solvent Free Technology
- High degree of flexibility @ > 35%, capable of accommodating structural movement compared with resin / epoxy / bitumastic coatings of <1.0%
- Superb adhesion to steel, concrete, GRP and many other substrates.
- High levels of impact and chemical resistance.
- Long life performance with minimal maintenance
- Easy clean, ceramic tile-like finish
- Excellent track record for applications such as drinking water tanks, cooling towers, reservoirs etc.
As each tank was drained the extent of the osmotic blistering of the existing coating became evident. The previous specialist had decided to paint the blue epoxy coating directly onto a bituminous coating.
The internal surfaces were manually prepared to remove the existing coatings and to provide a surface profile of 0.75mm to accept the new coating. All joints were stripe coated with a base coat (Grey) of DWPU to build up the thickness in these critical areas before applying to all internal surfaces at a nominal thickness of 400 micron.
The above was repeated with a top coat (blue) of DWPU applied to all internal surfaces. When the coating had cured, each tank was disinfected to PD855468:2015 before being re-instated to normal operation.
The ball valves were also replaced with Aylesbury Keraflo KB type fully variable delayed action float valves, suitable for tanks with or without raised valve chambers.
All tanks were then insulated using BCO MMMF insulation and other remedial works completed to ensure each tank complies with the Water Supply (Water Fittings) Regulations 1999.
At handover, a full photographic completion report along with a 10-year guarantee was provided to a very pleased customer.