From the moment metal is worked, it is subject to flaws, deterioration, or other forms of loss. For any industrial asset, corrosion is a particularly significant threat, weakening the integrity of the entire structure, and, if not detected and monitored, creating irreparable damage. It can be introduced in many ways and at any point in an asset’s lifecycle, creating a constant need for monitoring and detection methods. In addition, corrosion does not discriminate. It flourishes in a variety of environments, including oil and gas pipelines. From general wall thinning/erosion to gouging to complex corrosion clusters, various measurement technologies make the location, size, and classification of any type of corrosion defect possible. The ROSEN Group operates the largest fleet of corrosion detection tools in the industry. Paired with a variety of integrity assessments, the following technologies, either individually or in combination, assist in managing the risk presented by this overwhelming threat:
The power house technology in terms of metal loss detection is based on the high-resolution Magnetic Flux Leakage (MFL) method. State-of-the-art permanent magnets are used to magnetize the pipe wall to saturation level in the axial direction (typically 10kA/m - 30 kA/m). Achieving a high magnetization level is essential to differentiate corrosion from other pipeline features like inclusions and surface defects.
Under normal conditions (no flaws present), the magnetic flux can travel through the pipeline undisturbed. In the presence of internal or external metal loss, the flux “leaks” out of the pipe wall and is recorded by hall-effect sensors. The hall sensors are oriented within the magnetic field and provide coverage of the entire circumference.
The character, amplitude, and various other measurements of the sensor signals are used to determine the depth, length, and width of the detected metal loss.
- Accurate and precise feature classification and sizing
- High magnetization for high quality of data
- Best accuracy in feature length measurement
- Reduced tool dimensions and better inspection reliability as sensors are integrated into a single sensor unit
- Safe negotiation of dual- and multi-diameter pipelines, 1.5D bends and ID reductions up to 15% ID
- Wide range of tools (sizes from 3" to 56" available)
- Applicable in both liquid and gas medium
ROSEN also offers the market leading MFL-A Ultra technology, which is able to detect even the smallest pinhole. In addition, the use of AutoData machine learning algorithms allows for a high level of automation, thereby reducing the “human factor” impact.
The measurement principle of MFL-C is in fact very similar to that of MFL-A, as it also applies magnetic flux leakage. However, it changes the direction of the magnetic field from axial to circumferential. Tools equipped with this measurement technology circumferentially magnetize the pipe and detect axial features. This makes it suitable for long seam defect detection and narrow corrosion, channeling, crack-like features, and preferential seam weld corrosion.
The principle behind Internal Eddy Current (IEC) measurements relies on the creation of eddy currents (ECs). Based on electromagnetic induction, EC testing involves placing a cylindrical coil, which is carrying an alternating current close to the pipeline. The current in the coil generates a changing magnetic field and thus produces eddy currents in the pipe wall. To collect and later assess data, the variations in the phase and magnitude of these currents are monitored by using a second coil or by marking changes in the current that flows in the primary coil.
The IEC technology accurately detects and sizes shallow internal corrosion features completely independent from the pipe wall thickness. A few key advantages of EC are:
- Can be applied in a liquid or gas environment as well as in cladded pipelines
- Suitable for extra-heavy-wall pipelines and not affected by heavy-wall segments or crossings
- Supports the identification of small diameter pitting and pinhole features
- Provides accurate mapping of internal surface for baseline surveys
- Allows for differentiation between mid-wall features and small internal pitting
- The flexible nature of this technology allows for unsurpassed passage capabilities versus all other corrosion inspection tech.
UTWM is the most obvious technology for corrosion detection in pipelines transporting liquids. Ultrasound as a measurement principle is well accepted in the industry as an established method for the quantitative wall thickness measurement and for the detection and sizing of metal loss features.
This technology applies an ultrasonic transducer to generate an acoustic wave directly in the sensor probe that propagates through the liquid medium and the pipe wall. This transducer is also able to record the reflections caused by the internal and external pipe wall. This allows for the thickness of the wall to be assessed and assists in distinguishing between internal and external metal loss.
Optimized to detect and accurately measure internal and external anomalies such as corrosion, lamination, gouging, pitting, narrow axial, preferential seam weld corrosion and other metal loss features, UTWM offers a series of key advantages:
- Accurate and precise feature classification and sizing, particularly regarding general thinning
- Absolute wall thickness river bottom profile assessment through high resolution quantitative wall thickness measurement
- Reliable differentiation between corrosion and lamination
Thanks to our extensive experience in pipeline cleaning, we also offer dedicated cleaning programs for liquid pipelines, allowing for the optimal application of UT and reliable detection of features.
From Detection to Management
Although gathering the data for the detection and identification of corrosion features is half the battle, the ROSEN Group’s integrity team is able to turn data into knowledge and offers a long list of assessments dedicated to corrosion management. These include:
- Corrosion risk assessments & corrosion management strategies
- Corrosion control, mitigation, & prevention
- Corrosion modelling, growth, and lifetime predictions
- Cathodic protection & coatings consultancy
- Corrosion Consultancy