ABSTRACT
The construction of a port expansion project in Arabian Gulf for a major operator included the surface-based structures such as capping beams and reinforced concrete piles. In 2009, a criticality assessment study was conducted that established the requirement of an impressed current cathodic protection system for all piles included in offshore structure. The installed CP system was operational since August 2011 and was remotely monitored. The monitoring data showed that all the surface-based structures such as capping beams adhered to the requirements of BS EN 12696 with regards to polarization and depolarization. However, the reinforced concrete piles showed an initial negative polarization followed by steady state condition. Thereafter, the polarization project requirements were not achieved. Later in 2014, it was requested by the Operator and the Contractor to conduct a diagnostic investigation of the CP system and review the requirement for cathodic protection for the piles. This paper presents the review of impressed current cathodic protection system data, reports, adopted methodology, analysis, results interpretation and key findings.
INTRODUCTION
Background
The construction of a port expansion project in Arabian Gulf for a major operator included the provision of cathodic protection system for various offshore facilities. In addition, the impressed current cathodic protection (ICCP) system envisaged on the project included the reinforcement in two distinct types of structures:
Surface based structures such as capping beams; and,
Reinforced concrete piles.
A criticality assessment of the structures was carried out in 2009. Amongst other things the initial assessment recommended that all piles should be cathodically protected. The client asked to update the criticality assessment in 2014 based on as-built data; in particular the as-built data showed that all piles were encased in steel sleeves. The assessment was amended in 2014, however the methodology adopted in these revisions was not clear which required a clear explanation of the changes made as advised by the Operator.
The ICCP System was operational since August 2011 and was remotely monitored. Monitoring data showed that all surface based structures adhered to the requirements of BS EN ISO(1)12696 1 with regards to polarisation and depolarisation, however the reinforced concrete piles showed an initial negative polarisation followed by steady state condition thereafter and the polarisation project requirements had not been achieved.