MMO Ribbon Anode in Grid Configuration for Tank Bottoms Cathodic Protection

Apr 19, 2021

MMO Coated Ribbon Anode in Grid Configuration for Tank Bottoms Cathodic Protection

An impressed current cathodic protection (ICCP) is employed for tank bottoms corrosion since it  allow low profile used between the tank bottom and any secondary containment liner or existing tank bottom in the case of a double bottom tank.

The field-erected anode grid configuration is one of primary cathodic protection configurations  of MMO anodes for tank bottoms.

It adopts MMO ribbon anodes field cut into strips and laid out in parallel. It consisted of coated ribbon anodes placed on 1.5 m centers with conductor bars every 7.6 m . At every point of intersection, the anode ribbon was resistance welded to the conductor bar. The ribbon was 6 mm thick by 6.4 mm wide; and the conductor bar was 1 mm thick by 13 mmwide. Eight power feeds and six reference cells were installed as part of the system.The MMO ribbon and titanium conductor bars are field tack welded at the intersections. Separate power cables are then tack welded to the titanium conductor bars and the cables are fed back to a junction box.The tank is used for storage of surface water run-off from heavy rains and is therefore operated at ambient temperature. For this application, the anode grid was designed for a 50 year life at a current capacity of 1.1µA/cm2.

Cathodic protection with the MMO coated titanium ribbon in the grid configuration is easy to handle and install. It has even current distribution over the entire tank bottom, and no need  for calcined petroleum coke backfill, saving time during installation and eliminating the possibility of the coke creating a system short.