Tank Internal Installation Works
Tank Internal ICCP System:
Storage tanks are protected by internal lining in accordance with Project Specification and impressed current cathodic protection (ICCP) with mixed metal oxide (MMO) coated titanium tubes.
All required installation works are completed before internal coating application. For ICCP system, generally suspended MMO tubular anodes are selected. Anode wires are suspended inside the tank by using stranded rope and tethering lugs are welded to tank bottom. MMO anode ropes are fastened tight through welded lugs to prevent short circuit between Anode/Cathode systems and to stabilize anodes against water movement inside of the tank.
Anode strings may be terminated in Anode Splice Boxes where they will be cabled to a Positive Junction box (PJB) or directly to TR Unit.
All cables are installed and clearly identified in the junction boxes before termination. The junction boxes are installed in such a manner that easy access to the junction boxes is maintained.
Tank Internal Galvanic System:
Main concept of cathodic protection system is to provide homogenous cathodic protection current distributed to cathode surface area. Within that scope, all necessary cathodic protection calculations are performed to ensure that amount of CP current and to ensure linear CP potentials everywhere, anodes are distributed to structure surface area homogenously. Location of the anodes and different anode types/sizes are checked in such a way that they are in accordance with project specifications.
To provide linear cathodic protection current, providing low resistance has significant role for easy ion transfer via electrolyte. Within that scope, anodes are fully welded, or bolted to a support on steel structure (cathode).
Installation on coated surfaces may require special precautions, such as:
– Anode cores and supports may need to be coated to the same standards as the structure coating.
– During installation of anodes on coated areas, coating damage by dragging or dropping anodes or by weld spatter, etc. need to be avoided.
– If coating operations are required after the installation of the anodes is completed, the anodes are protected from painting by wrapping them in paper or covering them with soft soap. The paper wrapping has to be removed after painting. Plastic wrapping is not recommended, and grease should never be used for the protection of anodes during painting.
