The Vertical Tension Anode System: A Cost-Effective Option for Fixed Offshore Platform Cathodic Protection Life Extensions

Abstract

The Vertical Tension Anode System (VTA) is an Impressed Current Cathodic Protection (ICCP) system that can be installed without divers or ROV equipment. It is a cost-effective option for the life extension of brown field offshore structures whose original aluminum anodes are depleted. In June of 2013 four large offshore platforms in the Gulf of Mexico, all with low cathodic protection potentials due to depleted aluminum anodes, had VTA systems installed in a single, continuous construction schedule. These structures were in water depths between 68 and 80 meters (225 and 262 feet), with an average cathodic protection current requirement of 1000 amps. Total installation time was only twenty-three days, which included loading, mobilization to each structure, and offloading at the end of the job. Each platform required two VTAs, thus less than three days per VTA was required. A topside crew of 10 men, an inspector, and an experienced VTA installation technician made up the installation crew. The equipment included just a few air winches, a large air compressor, a welding machine, special VTA deployment spool racks, and miscellaneous hand tools. Since the entire system was installed from topside the client was provided great savings over sled type impressed current installations or aluminum anode type systems.