Civil Engineering Reference
In-Depth Information
often requiring approval from the client's engineer who retains design
responsibility.
An impressed current cathodic protection system should be designed by
a competent person with correct training and experience. In Europe a new
standard BS EN 15257: 2006 'Cathodic protection - competence levels and
certification of cathodic protection personnel' is now being implemented
in the UK by courses run by the Institute of Corrosion and the Corrosion
Prevention Association for levels 1 and 2. Certificates are awarded by the
Institute of Corrosion with level 3 certificates awarded after assessment of
experience.
The design of a cathodic protection system is described in BS EN
12696:2000. It requires following steps:
• The selection of anode type or types (more than one may be needed)
• Anode layout and the breaking down of the structure into zones
• Determination of current requirements by selection of a suitable current
density on the steel and calculation of the steel surface area for the
concrete components of the structure
• Design of reinforcement connections
• Design the cable layout (numbers, sizes, junction boxes, conduits, cable
trays etc.)
• Location and number of embedded reference electrodes and other
monitoring probes
•
Power supply location, type, capacity, a.c. power provision and remote
monitoring telephone line or other telecoms options
•
Documentation - drawings, specifications, method statements, quality
plan, operations and maintenance manual.
Once a contractor is approved with necessary Heath & Safety, Quality
Plan and other necessary systems in place, the usual installation process is
as follows:
1 Conduct concrete repairs while checking electrical continuity of the
steel and making negative connections to the reinforcement.
2 Install reference electrodes and other monitoring probes.
3 Install the anode system or systems.
4 Install wiring system.
5 Install control and monitoring system and wire up the system.
6 Carry out pre-commissioning checks.
7 Energise the system.
8 Commission the system.
9 Provide operation and maintenance manual to client containing all
necessary drawings, documents and manuals.
