Seawater is one of the most corrosive of naturally occurring environments. Metallic structures immersed in seawater are subject to severe corrosion including close inshore structures such as harbours, jetties and piers, constructed from sheet or tubular piles.
It is essential that these structures be protected against the ravages of corrosion by the application of cathodic protection in order to achieve or exceed its design life
BAC specialises in the design, manufacture and supply, installation, commissioning, monitoring and maintenance of cathodic protection systems for these marine structures.
BAC utilise, in the main, impressed current cathodic protection systems with installed capacities running into hundreds of amperes for large, bare steel structures. Impressed current cathodic protection current is provided by either manual or automatically controlled transformer rectifiers powering impressed current anodes specifically designed to operate in the conditions prevalent on site.
BAC carry out their designs in accordance with international standards under the control of our ISO 9001:2000 certified quality management system. Whilst system design lives in excess of 25 years are normal, it is inevitable that some anodes will be damaged over this period and require replacement. BAC designs ensure that such replacements can normally be effected without resorting to the use of divers.
BAC willingly provides advice and outline system design for cathodic protection of Harbours and Jetties. In order to do this, as much of the following information should be provided - the more information supplied, the closer our proposals will be to the final designs:
- Type of piling
- No/length of piling
- Depth of piling above and below seabed
- Specification for pile coating
- Method of continuity bonding
- Layout drawings
- Classified hazardous area
- Facilities for isolation from other structures
- Power supply type and availability
- Existing CP Systems
Ships and Boats (Impressed Current Systems for Water Jets on Fast Ferries).
The material used for the hull of fast aluminium vessels withstands corrosion in seawater very well under normal operation conditions, due to the passivating oxide layer of the surface.
Sacrificial anodes made of Aluminium alloy are normally used for cathodic protection of the critical areas, but for waterjets and thruster tunnels with high water velocity, practical experience have shown, that the lifetime and capacity of sacrificial anodes are limited, and do not give sufficient protection.
BAC has solved the above mentioned problem by the design of an Impressed Current Cathodic Protection (ICCP) system. The "Award" systems, which have been installed in a number of vessels already, secures full protection and avoid the risk for overprotection, by means of strategically installed reference electrodes, used for control and monitoring.