The DR-2 utilizes both zinc and silver / silver chloride reference electrodes for accuracy and longevity.
The Polatrak DR-2 is a rugged, dual-element reference electrode designed for permanent subsea attachment to provide cathodic-protection potential data. A standard DR-2 is designed to last 20 years. Both electrodes are housed in the machined Delrin body, giving the assembled DR-2 excellent impact resistance. Deepwater manufactures all components in-house to meet our rigorous QA/QC standards.
The sintered Ag/AgCl reference electrode provides very accurate potential data to monitor polarization of the structure; the heavy-duty zinc electrode element provides a long-term, ultra-reliable, low-resolution electrode. Remote-control monitoring systems are standard on new structures; Polatrak systems give you the option to tie into communication lines, providing remote cathodic-protection monitoring via existing infrastructure.
New offshore structures
For new offshore platform jackets and drill rigs, as well as SPAR, TLP, and FSU / FPSO structures, a pre-installed cathodic-protection monitoring system utilizing a DR-2 offers operators the reliability of a 20-year monitoring system. Reference electrodes can be welded at all critical areas and hardwired to the surface, integrating with existing electrical systems.
Existing offshore structures
For existing structures, the DR-2 must be attached by RetroClamp to critical areas where either a tubular member, riser or flange is present. The RetroClamp can be installed by diver or ROV, and the rugged conductor cable from the DR-2 can be routed to the surface with standard cable clamps. The splash zone will require an I-tube for protection unless the cable is routed through an existing J-tube.
New and existing subsea equipment
For subsea equipment without a nearby topside area to route cable to, the DR-2 must be connected to a SunStation readout monitor. The SunStation is powered by the lights from an ROV, and can be pre-installed topside or retrofitted via ROV. See the SmartStation for an example of how the DR-2 can be retrofitted and interrogated underwater with the SunStation readout.
Much like deep-water equipment, subsea pipelines often lack a suitable topside area for a monitoring panel to be installed (with the exception of risers and pipeline sections near shore). For pipelines, the DR-2 is installed by ROV using a RetroClamp and connected to a SunStation readout. Again, see the SmartStation for details.
Structures with permanent cathodic-protection monitoring systems can be inspected subsea much less frequently, since interval surveys can be performed with a simple voltmeter.
The rugged design allows the DR-2 to be welded reliably to the structure and wired to the surface at minimal cost prior to deployment.
The double steel-wire armored cable can be free-routed on offshore structures with simple bands or cable clamps, saving the cost of conduit or duct systems.
The dual elements combine the high accuracy +/- 0.005 V of the silver / silver chloride electrode with proven longevity of the zinc electrode, making the instrument the most valuable reference cell available.
The DR-2 CD combines the standard DR-2 with an integrated current-density monitor (a large metal fin). The reference electrodes and the current-density monitor allow the operator to calculate data about the polarization of the structure.