Cathodic Protection specialists BAC Corrosion Control Ltd (BAC) have recently completed a project for the British Energy owned Heysham 1 Nuclear Power Station in Morecambe, UK.
Since installation, the power station’s back up cooling water system corrosion control provisions and some sections of the pipeline, over the 25 years of life, required material enhancements and enhanced corrosion protection. BAC was commissioned to install Isozin Zinc Tape and Zinc sacrificial anodes at various valve pit locations around the site to extend the service life of this back-up system.
Isozin Zinc Tape comprises a layer of 99.99% pure zinc 80 microns (0.08mm) thick with 25 microns (0.025mm) of adhesive which is protected by siliconised paper until installed. It is available in 50 meter long rolls and in widths ranging from 100mm up to 300mm.
The product is designed to cover unpainted iron, steel and light alloys to provide local corrosion protection that, in most cases, will last longer than the life of the structure being protected. The tape achieves both passive protection due to the Zinc Tape acting as a barrier coating as well as active protection due the tape acting as a sacrificial anode which will corrode instead of the substrate.
The project negotiations lasted for nearly 18 months during which time visits to site were made and stringent vetting of both BAC as a company and the personnel involved had to be undertaken by British Energy. Five members of the BAC staff were involved during the installation work which lasted 4 weeks in total.
The work carried out included the removal of any existing sub-standard coating, surface cleaning of the pipe work and valves and finally installation of the Isozin Zinc Tape, sacrificial anodes and surface tolerant epoxy paint. Thickness testing was conducted after the installation to confirm that the work carried out met the originally set out specifications by British Energy.