Originally developed in the 1970’s by Lockheed
- Originally designed to replace hanging and retractable ICCP Systems
- Can be used for Galvanic replacement / retrofit
- Quick Install (Typical 4 – 6 days)
- No diver or ROV requirement for install
- 20 Year proven system life
- Designed to withstand 100 year storms
Frequently Asked Questions
1) What is the Galvotec-Lockheed Vertical Tension Anode system? The Galvotec-Lockheed Vertical Tension Anode (VTA) system is a retrofit impressed current anode system that is installed within the perimeter of an offshore structure without the need for divers or ROV support.
2) On what type of structure is a VTA system best used? The VTA system is best used on fixed offshore platform structures with 3 or more legs in water depths between 30m and 125m. The candidate structure needs to have AC power onboard in order to operate the rectifier(s) that energize the VTA system anodes.
3) What is the life of a VTA anode system? 20 years is typical, but longer life systems are available. The system can also be removed and re-installed on a similar structure if decommissioning occurs before end of life.
4) What is the maximum current output of a single VTA string? The maximum current output of a single VTA string is 600 amps.
5) What are the platform power requirements for a VTA system? A small 350 amp system would only require 15 AC amp circuit at 480 volts, 3 phase, whereas a large 1200 amp system will require only 51 AC amp at 480 volts, 3 phase AC.
6) What deck space is required for a VTA system? Deck space would only be required for the installation of the rectifier(s) that power the VTA system anodes. A typical 450 amp rectifier has a 2m x .6m footprint. Large amperage systems consisting of two VTA strings may require a total of three rectifiers.
7) What is the fabrication time for a VTA system? The typical fabrication time for a VTA system is approximately 10 – 12 weeks since it is custom built for the structure on which it is to be installed.
8) How long will the installation of a VTA system take? Installation of a single string is typically one day once the crew is mobilized onsite and all rigging and tie down of installation equipment is completed. A two string installation generally requires just one additional day.
9) Are divers and dive boat required for the VTA installation? No divers or ROV are required for the typical VTA installation; it is considered a “diverless” installation – a great saving in total cost. A boat is usually needed only to transport the crew and equipment offshore and back unless the crew needs to be quartered on the boat.
10) How long will it take for me to see full protection on my structure once the VTA system is commissioned? The typical offshore structure generally requires about one month to polarize the structure’s potential from unprotected to a fully protected state.
11) What are the advantages of the Galvotec-Lockheed VTA system over other similar type systems?
A) The Galvotec-Lockheed VTA system is the only VTA system with a 40 year history of proven design life.
B) Each anode on the VTA system is individually powered with its own cable from the rectifier, so the output of each anode can be monitored and controlled. No other system has individual anode control.
C) The VTA system is designed so that each anode generates the same current regardless of position on a single string. No other offshore impressed current anode system can do this.
D) The VTA anode cables are protected within a multi-layered, armored bundle. The anode tension cables in other systems are not armored and are simply bundled and coated with heat shrink material.
E) The Galvotec-Lockheed VTA is the only system to utilize a platinum-niobium anode. The niobium substrate material will not break down until 90 volts, which far exceeds the system’s operating voltage (between 15-30 volts). Other systems utilize MMO anodes which have a titanium substrate; titanium can break down at only 12 volts, causing major operational failure if ever exposed.
F) The Galvotec-Lockheed VTA generates cp current at the depths on the jacket that require that current and as the current requirement increases with depth so do the number of anodes and current generating ability of the system therefore evenly applying current over the entire surface of the platform jacket. ICCP Systems that generate all their current at the bottom, remote from the structure, do not have the ability to evenly apply current to the entire jacket area at all water depths due to variations in water resistivity caused by the temperature changes associated with depth.
The Major Advantages Are:
- Even current distribution at all water depths
- Topside deployment (no divers)
- Most cost effective retrofit option for high current requirements
- Mature Technology
- Installed inside platform jacket
- With ROV assist has been installed on 1,700 ft. jacket (518 m)