SPG undertook a critical project at the Wessex Water Codford site, focusing on the removal and replacement of the retained coating system within the pressure filters. The original coating had experienced 100% failure, primarily due to poor inter-coat adhesion characteristics, leading to delamination and localized corrosion. This failure was exacerbated by stress cracking, most notably on the plenum floor within each pressure filter, likely caused by over-application of the coating.

To address these issues, SPG operatives utilsed a combination of mechanical tools and dry abrasive blast cleaning to fully remove the defective coating system. The process also included mechanical preparation of the plenum floor to reduce the quantity of blast media required, achieving the desired surface preparation standards more efficiently. The existing coating was found to be 5mm thick and applied in multiple layers, with poor adhesion between layers, further indicating inadequate surface preparation prior to the original coating application.

SPG’s team ensured all requirements for surface preparation met the specified BS EN ISO 8501-1SA2.5 standard. Throughout the project, precision was maintained with the use of an Elcometer grit comparator (Serial No. Gi6771) for visual surface assessment and an Elcometer surface profile needle gauge (Serial No. E224C-BS) for precise measurement of surface profile.

The result of this detailed remediation work is the successful application of both an internal potable water lining system and an external protective coating system across all seven pressure filter vessels. These vessels are now in full commissioning, ensuring the longevity and reliability of the water filtration system at Wessex Water’s Codford facility.