Vision Integrity Engineering Ltd Approach
Cathodic Protection is a key element to ensuring the safe operation of steel pipelines. It is a regulatory and code compliance requirement that pipelines have an external corrosion mitigation program in place. It is also a compliance requirement that cathodic protection systems are maintained and monitored.
Cathodic Protection Services
Initial Survey of New Piping Systems
Initial survey shall be performed as soon as practicable, but no more than 12 months after piping system installation.
Subsequent pipe-to-soil potential surveys, to verify cathodic protection, should be done as follows:
- As a minimum, once per calendar year.
- As an alternative to above, the frequency of pipe-to-soil potential surveys may be adjusted if it can be proven that the objective of corrosion prevention has been achieved.
Monitoring and Inspection
Cathodic protection facilities should be monitored and inspected in accordance with the following:
- All impressed current sources should be monitored at a frequency of once every 2 months. Longer or shorter intervals may be appropriate.
- Once per calendar year, all impressed current facilities should be inspected and maintained as part of a preventative maintenance program.
- Monitoring may be accomplished by onsite inspection or by evaluating corrosion survey data.
- The effectiveness of isolating devices, bonds and casing insulators should be checked during the pipe-to-soil potential survey.
Monitoring Techniques| Measurements
The following electrical measurements may be considered when conducting a periodic survey:
- Pipe-to-soil potential at test stations
- Close-interval pipe-to-soil potentials
- Pipe-to-soil potentials at compressor stations, meter stations, terminals and storage facilities
- Impressed current rectifier output
- Induced AC potential and current levels on pipelines
- Interference activity (e.g. Telluric, LRT, and other currents)
- Pipeline current
- Coating conductance surveys
- Electromagnetic field loss evaluation surveys