Case studies - Covac Completion Reports
For detailed documentation of some of the metal and steel water tank repair and refurbishment we have completed, please see the case study links below.
The internal surfaces of steel and galvanised steel water storage tanks and structures are often excessively corroded because the coating previously applied to the internal surfaces has approached the end of its useful life. More often than not, we find the internal surfaces have been coated with a non approved paint such as bitumen. These type of coatings usually have potentially carcinogenic properties that could leach into the water supply due the tar / high solvent content as well as being no longer WRC (Water Industry Council) / WRAS (Water Regulations Advisory Scheme) or DWI (Drinking Water Inspectorate) approved for potable / drinking water storage. The coating has usually come to the end of its useful life due to sub-film corrosion, low-film build and poor chemical resistance, general deterioration and progressive surface corrosion.
If left untreated, the internal steel substrate will be endangered with a continued risk from progressive corrosion and subsequently, micro aquatic bacterial growth including Legionella (potentially, leading to Legionnaires disease), Pseudomonas and Biofilm; this can lead to further deterioration in the tanks surface structure and contamination of the down services with the supply of unhygienic and potentially harmful water to the outlets.
We are all now under and obligation to ensure that water retaining structures comply with the practical guidance of ACOP L8 and subsequently, utilize products that comply with WRAS / DWI Regulations and, therefore, maintain “the cleanliness of the system and the water in it” and avoid the "use of materials that harbour bacteria and other micro-organisms or provide nutrients for microbial growth".
Another problem with larger, sectional steel water tanks is the mastic between the joints which, over time, begins to deteriorate and lose its elasticity. Consequently, the structure will start to leak from these areas which can be catastrophic in many cases.
Acothane DW Solvent Free Polyurethane offers numerous economic, technical and environmental features and benefits for use in steel water storage tanks.