Repair and improvement of an existing Cathodic Protection System for Crude Oil Tank Bashair Marine Terminal, Port Sudan
In March 2017, Tecnoseal Industry was awarded for the repair of the existing Cathodic Protection System of a large crude oil tank of the Bashair Marine Terminal, 25 km south of Port Sudan, the new Sudanese crude Oil exporting port to the world. The Terminal is designed to export 1˙200˙000 bop, and proposed to be increased to 2˙000˙000 bop.
The storage tank has a diameter of about 80 meters and height of 15 meters, designed for half a million barrels at a time. An Impressed Current Cathodic Protection System (ICCP) using Mixed Metal Oxide Titanium ribbon anodes was originally installed 18 years ago for the protection of the bottom plates.
The system was composed by No. 12 concentric loops of MMO Titanium ribbon spaced of abt. 3 meters and connected together by No.12 conductor bars of pure Titanium installed along the radii of the bottom and welded together at the center. Polarization potentials are measured by No. 9 Zinc reference electrodes installed in a later stage.
About 1 year ago, the original connections of the cables from the T/R unit to the anodes failed, and the system was shut down.
The storage tank was put out of service, emptied and de-sludged. Then, our job was divided in the following steps:
- Measure of natural potentials of bottom plates;
- Execution of a 40cm-wide cut on the tank bottom, to the external rim to the center;
- Improvement of original connection of Titanium conductor bars;
- Installation of a new Titanium conductor bar;
- Connection of Number 6 power feeding cables;
- Installation and connection of a new Positive Junction Box;
- Testing, startup and commissioning.
The repair works completely restored and improved the continuity of the positive circuit, allowing the C.P. system to be started-up again and commissioned. Renewed functionality was confirmed according the “100 mV residual polarization” criterion, measuring the Instant-off potentials after achievement of sufficient polarization.
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