The lime hoppers at Elmer WTW were suffering from product not flowing freely as a result of the rough and porous concrete surfaces.
As requested we proposed a suitable drinking water approved tank lining that would help the stored lime flow more freely.
Initially all surfaces were prepared by method of abrasive blasting – removing surface laitance from the concrete and preparing the steel to SA2.5. The blast standard was maintained using dehumidification equipment.
To ensure excellent adhesion of the new tank lining the surface profile was checked using surface profile needle gauges, and the surface cleanliness after cleaning checked and recorded.
Sealing seams and crevices using polyurethane sealant
All seams and crevices were sealed using a regulation 31 approved polyurethane sealant. This was followed by the application of a stripe coat of BASF M808 to all angles and edges of the steel surfaces. Stripe coating is essential to ensure full film build in areas where coatings pull thin through gravity and surface tension, making this an essential stage of the tank relining process.
This stripe coat was followed by two full coats at 300 microns dry film thickness of BASF M808.
Applying a cementitious fairing coat
Once the steel had been treated to prevent corrosion from occurring a cementitious fairing coat was applied to the concrete sections in the form of BASF Masterseal 586. The concrete was highly porous and blow holes present must be sealed prior to coating application – as blow holes cannot be filled with paint alone.
The fairing coat was allowed to set and thoroughly dry. The moisture content was checked using a Tramex Moisture meter to ensure compliance with tank lining manufacturers recommendations.
Applying the tank lining
BASF M808 DWI approved tank lining was then applied in three coats as per the manufacturers recommendations. As with all of our coating applications atmospheric monitoring took place throughout application in order to ensure the correct climatic conditions for application of the tank lining.
As per our standard quality assurance the new tank lining was checked for pin holing and porosity by DC holiday spark testing. With any pin holes present in the new tank lining being marked and made good using the same tank lining material.
This tank lining project was particularly challenging as a result of the unusual shape of the tank. Fortunately we had a great team on site who managed the challenges on site extremely well.