FiGS® CP survey provides the possibility to measure current density on structures and current output from anodes. The accuracy and resolution enables the sensor to detect very small coating defects on critical structures and pipelines, including buried and rock dumped pipelines.
FiGS® CP survey measures the electric field gradient vector and can detect electric currents in seawater. The sensor design allows for highly accurate measurements with a resolution and detection level that surpasses all other field gradient sensors available on the market.
The technology has a wide area of application including, but not limited to:
- Measurement of current output from anodes
- Measurement of current density on pipelines and structures (bare steel, coated steel and concrete)
- Detection of coating holidays / defects on pipelines, including buried pipelines
- Measurement of current drain to buried structures such as piles and wells
FiGS® CP survey can be used to detect coating defects on pipelines that are exposed, partly buried, buried and rock-dumped. The sensors’ ability to detect very small FG values means that even smaller coating defects can be detected and measured accurately. An area of 10cm2 of seawater exposed steel gives an FG value of ~0.4μV/ cm, measured 30cm from the pipe. This is 4 times larger than the detection limit of the sensor. This type of coating defect cannot be detected by any other sensor today.
Its ability to measure the direction of the electric field ensures that the detected signal originates from the pipe in question, and not from debris or any other sources of electric noise. Typical cases may be critical 13 Cr pipelines and pipelines exposed to trawling.
This type of coating defect cannot be detected by any other sensor today
The sensor also allows for examination of buried or rockdumped pipelines. The signal strength gets weaker at longer distance from the pipe, but burial depths of 1m is tested and feasible. For inspection of buried anodes, measurements can be made for burial depths of 2m or more.
Pipelines with Direct Electrical Heating (DEH) will have a significant current flowing in the pipe wall and anodes act as discharge points for this current. If a coating damage occurs, this will act as a discharge point, resulting in severe metal loss. The FiGS is ideal for detecting such damages, thereby enabling the operators to take pre-emptive action.
FiGS® CP survey can be used to accurately measure current density on coated and uncoated steel, as well as concrete structures. This becomes relevant when the operator plans for lifetime extension, or if regular CP surveys show anomalies. Current density is the most important design factor in CP designs and, in certain cases, the actual values may deviate considerably from the design values. Today, there are no other means of accurately measuring the current density directly on the structure.
The sensor can also be used to measure the current output from galvanic anodes, both on structures and pipelines, which is important data when evaluating remaining lifetime of the anodes.
Ideal for planning and evaluating life extension
FiGS® CP survey is also suitable for measurement of current drain to buried structures such as piles and wells. By mapping the seabed around the buried structures, the FiGS data can be used to calculate the amount of current delivered into the seabed.