Sergey Zheleznyakov
Head of the corrosion diagnostics laboratory
Corrosion survey
Comprehensive corrosion survey of trunk pipelines
Coating defects found in time can be fixed before a failure and extend the life of the pipeline. More than 4,700 km surveyed.
KM 01
Three stages of every diagnostic job
- I
Organisational
We study design, as-built and technical documents and earlier survey materials. We settle the scope of electrometric work and confirm the asset is ready.
- II
Technical
Field electrometric measurements along the route and in control pits.
- III
Analytical
We process the data and write the report and recommendations.
KM 02
What the measurements show
Diagram: pipe-to-soil potential along the route. Where the curve rises above the protection criterion, the coating is damaged or protection is insufficient. An illustration, not data from a real asset.
KM 03
Field work
- Survey of cathodic protection units: operating modes, anode groundbed resistance, degree of redundancy.
- Pipe-to-soil potentials and transverse gradients with stations on and off, at a step of no more than 5 m.
- Coating resistance assessed from the attenuation of a low-frequency generator signal.
- Influence of stray currents and high-voltage lines.
- Protection of the pipeline along its length and over time.
- Pipe-to-casing contact at crossings and the condition of casings.
- Soil resistivity (step up to 100 m) and depth of cover (step up to 5 m).
- Satellite positioning of landmarks and measurement points.
- Control pits, with non-destructive testing where needed.
KM 04
Instruments and method
Coating quality and protection are checked by the intensive measurement method. To obtain an objective off-potential we fit synchronised current interrupters in the cathodic protection stations, so every unit that affects the measuring point switches off at the same moment.
We work with instruments by Weilekes Elektronik, Radiodetection, Seba KMT and Sonel.
KM 05
What the client receives
A technical report on the survey:
- Conclusions on corrosion protection and on the corrosion condition of the pipeline.
- Recommendations on cathodic protection and defect lists with a repair priority order.
- A corrosion map of the section showing zones of high and elevated corrosion hazard.
- Records of field electrometric measurements and a summary list of GPS coordinates.
- Reports on control pit work.
4,700+km
of trunk pipelines given a comprehensive corrosion survey
10
process sites (pumping stations) surveyed with equipotential curves
280+km
of newly built pipelines checked for coating quality
260+
underwater crossings given technical diagnostics
Figures as published by the company.
KM 07
Photos from site
Company photographs
KM 08
Questions and answers
What are intensive measurements?
Measurement of pipe-to-soil potentials and transverse gradients with the cathodic protection stations switched on and off, at a step of no more than 5 m.
Which documents are needed before work starts?
Design, as-built, handover and technical documents, plus earlier survey materials including in-line inspection and ultrasonic results.
Do you survey process sites as well as the line?
Yes. Ten process sites (pumping stations) have been surveyed, with equipotential curves plotted.
Describe your asset and we will scope the work
Diameter, length, product, commissioning year and earlier survey documents help us answer to the point.