Abstract:

In this paper, the impressed current system (platinum cadmium) was investigated in terms of capability to polarize structures submerged in seawater at Qua Iboe field Nigeria. Data for potentials were generated by the drop cell method with Ag/AgCl reference electrode and digital multi-meter and analyzed. These structure potentials were measured at various elevations of platform tagged top, middle and bottom from the deck at five different measuring locations labeled south, east, west and center of platform. It was observed that measured structure potentials increased from top to the bottom of seawater because of higher corrosion rate at the surface due to environmental factors coupled with the effects of IR (Voltage) drop with sea depth. The potential values obtained in most cases fell within –0.956V and –1.99V. The recommended range of potential values is – 850mV to – 950mV. Hence, the facilities are overprotected, though this is uneconomical, and leads to hydrogen embrittlement.