Pipeline Cathodic Protection

Application Notes

Application Background                                                                                                                                                                                          Printer Friendly Version
Pipeline cathodic protection has been known about and applied to metal structures since last century. The principle of cathodic protection is simple. Corrosion is reduced by two methods

unidata-pipeline-cathodic-monitoring

The first method is to connect the metal of the structure to a more easily corroded metal, called a sacrificial anode such that the sacrificial anode corrodes faster than the metal of the structure. Small vessels have these to protect propellers from corrosion and water heaters have these to minimise corrosion in water heater tanks.

Pipeline Cathodic Protection

The second method is to apply opposing current (this is called an impressed current system) forcing the local anodes to be polarized to the potential of the local cathodes therefore stifling corrosion cells.

Pipelines are generally protected by impressed current systems and there are many expert cathodic protection companies worldwide advising pipeline operators on cathodic protection.

Application Detail

Many oil and gas pipelines traverse very remote regions and there is a need to make sure the cathodic protection systems remain in operation to maintain pipeline integrity.
These systems typically have rectifier stations at various points along the pipeline which take primary alternating current power, perhaps from a local power supply of a local generator, and rectify it to provide a low voltage and high current to apply to an anode buried in the ground.

Pipeline Cathodic Protection

Through this method the pipeline is protected from corrosion, however there is a need to monitor the performance of these systems as follows

  • the rectifier station status needs to be monitored, to ensure the voltage and current applied is correct
  • the pipeline / structure needs to be monitored at many points to ensure the small potential is correct along the pipeline to the next rectifier station

The rectifier station may have a small RTU with a Modbus interface to allow it to be controlled and monitored by a central SCADA system, and this would be common in high population areas where there is plenty of power and communications structure. The rectifier station may also have a simpler system of analog and digital inputs on the rectifier status, perhaps also local power generator status and fuel status and other local parameters.

Oil and Gas Pipeline Measuring Equipment

For the rectifier station a Neon Remote Terminal or Module can monitor Modbus channels and / or individual analog and digital inputs and outputs. There may be a need to make adjustments to the applied voltage/ current and these can be enabled to be remotely managed.
This system would typically be housed in a metal structure, with termination strips and a solar panel and battery and a solar recharge system to the power supply is independent from the rectifier station power supply.
Telemetry would be needed to provide the rectifier station status and possible control from the pipeline operations centre. This could be cell phone based or satellite modem based, more likely satellite modem based as the pipeline is likely to traverse very remote areas.

Perhaps the rectifier station would need to communicate with the central Neon Server every 15 minutes to communicate readings to be displayed on a Central Neon Server and also report out status to a central pipeline SCADA or other management system.

Pipeline Cathodic Protection Equipment

The other measurement points along the pipeline also need to be measured, and this is a very simple occasional measurement of a very low voltage level of the pipeline structure when compared to earth.
For the measurement station points a very small Neon Remote module could be used, with a small lithium battery pack, or a very small solar panel strip supply for convenience, as the power requirements are low

pipeline cathodic monitoring

Telemetry would be needed to provide the occasional voltage readings from the measurement points, but quite infrequently, perhaps read the voltage hourly, store it locally, and then and transmit the data to the central neon server daily, to minimise the power consumption and satellite airtime charges.

Typical Configuration

Options for Neon Telemetry - NRT / RTU / Field UnitsUnidata Part NumberDescription
Cellular RTU 3G2013F-AB03Neon Metering Module 3G with Antenna and Li Battery
Cellular RTU 4G2013F-AB04Neon Metering Module 4G with Antenna and Li Battery
Cellular RTU 3G - Industrial2016F-AB03Neon Remote Terminal 3G with Antenna and Li Battery
Cellular RTU 4G - Industrial2016F-AB04Neon Remote Terminal 4G with Antenna and Li Battery
Low Earth Orbit Satellite Globalstar2015E-AB0Neon Remote Terminal - Satellite Globalstar Modem with Antenna and three Li Batteries
Ethernet2017E-0B0-1 or 3NRT Ethernet with single or triple Ethernet Ports
with three Li Batteries
Equatorial Orbit Satellite - Inmarsat2018E-AB0-1 or 3NRT Ethernet with single or triple Ethernet Ports
with three Li Batteries
LCD Display2500ENRT LCD Display
NRT Field Termination Strip2103F2015E,2016F,2017E, and 2018E NRT FTS
NRT Firmware Option2303A-8M8M Extended Memory Option
NRT Firmware Option2303A-8M-CAM8M Extended Memory & Serial Camera Option
NRT Firmware Option2303A-CAMSerial Camera Option
Options for Neon Application Software - Customer ServerUnidata Part NumberDescription
Neon Application Software2302ANeon Server Software Licence Incl 5 NAL
Neon Application Software2302A-10Additional 10 NRT Access Licences
Neon Application Software2302A-20Additional 20 NRT Access Licences
Neon Application Software2302A-50Additional 50 NRT Access Licences
Options for Neon Application Software - Unidata ServerUnidata Part NumberDescription
Neon Application Software2301ANeon Data Initial Subscription Setup Fee
Neon Hosting Service2301A-01Neon Data Service Fee for 1-50 NRTs
Neon Hosting Service2301A-02Neon Data Service Fee for 51-100 NRTs
Neon Hosting Service2301A-10Neon Data Service Fee Metering
Options for Conventional Dataloggers / Field UnitsUnidata Part NumberDescription
Standards Starlogger6004D-11Red Logger 512K with Alkaline Battery
Display Starlogger6004D-21Blue Logger 512K with LCD and Alkaline Battery
Prologger7001D-11Green Logger 1M with LCD and Alkaline Battery
Micrologger8010C-EURMicrologger 512K
Starlogger Field Termination Strip6103E6004D FTS
Prologger Field Termination Strip7100E7001D FTS
Starlog V4 Management Software6308A-AUEStarlog V4 Full Licence Key