MDS Pro’s SMFL and LFM uncover every pipeline threat in one run.
MDS™ Pro is a cutting-edge in-line inspection (ILI) tool that combines multiple advanced sensors to provide a comprehensive survey of pipelines in a single inspection run.
By collecting six data streams at once (geometry, ID/OD discrimination, low-field MFL, high-field axial MFL, SpirALL® MFL, and mapping), MDS Pro provides pipeline operators with a complete integrity assessment while eliminating the need for multiple individual tools.
This one-run approach reduces inspection times and costs. MDS Pro’s SpirALL Magnetic Flux Leakage (SMFL) and Low-Field Magnetic Flux Leakage (LFM) technologies deliver unique benefits: SMFL enhances detection of axial (longitudinal) defects, and LFM reveals ‘hidden’ material issues like hard spots.
SMFL: SpirALL MFL for axial anomaly detection
Traditional MFL tools magnetise the pipe axially, which best finds general metal loss and circumferential anomalies. SMFL, by contrast, induces a spiral magnetic field in the pipe wall. As a result, axial anomalies trigger a clear signal in the SMFL data.
The advantage of this is that SMFL detects axially oriented defects that axial MFL can struggle with. Examples include seam weld flaws (lack of fusion, hook cracks), selective seam weld corrosion (SSWC), or narrow axial metal loss features that run along the pipe axis. In an axial field these sorts of flaws might produce weak indications, since the magnetic field is parallel to the anomaly. The spiral field, however, cuts across them, creating a signal in the data. In essence, SMFL closes the detection gap for longitudinal seams and cracks. SMFL can reliably flag long-seam corrosion or crack-like anomalies that would be under-called by traditional MFL. This makes SMFL a key technology for assessing seam weld integrity – helping find seam crack-like or SSWC anomalies early, before they grow towards an increased threat to pipeline integrity. Additionally, by comparing SMFL and axial MFL signals together, analysts can distinguish defect geometry. If SMFL sees a strong indication but MFL doesn’t, it’s likely an axial planar flaw rather than corrosion. Using the combined datasets together thus improves the characterisation accuracy and helps in avoiding false calls.
“SMFL on MDS Pro revealed seam-weld anomalies that would have been missed with a conventional axial MFL tool,” said senior MDS Pro analyst Kevin Tyler, referring to seam crack indications that axial MFL alone did not highlight. “Combining SMFL and axial MFL in one run gave us confidence no seam threat slipped through.”
This feedback underlines SMFL’s value in pipeline operations: it provides a dedicated lens for longitudinal threats. By enhancing detection of fatigue-prone seam defects, SMFL helps operators mitigate risks due to cracking. In turn, this extends pipeline life by enabling proactive repairs on seams and axial flaws.
LFM: Low-field MFL for material property insight
Low-field MFL is an innovative technology included in MDS Pro system that magnetises the pipe at a lower field level than standard high-field MFL. High-field MFL saturates the steel, mainly revealing metal loss. LFM, by keeping the pipe below saturation, maintains the magnetic response sensitivity to the magnetic permeability. Permeability shifts occur due to material properties or increased levels of the pipe steel.
LFM excels at spotting variations in material or increased level of stress in the pipe, in addition to metal loss. For instance, hard spots – localised hardened areas from manufacturing or welding – show up as distinctive LFM signals. They often don’t have metal loss, so depending on the morphology of the hard spot, signals in axial MFL might be ignored.
Conversely, the altered microstructure causes a permeability change that’s detectable in LFM data. Hard spots matter because they can be brittle and crack under stress. With LFM, operators can find these hard spots and treat or remove them before they become crack initiation sites. LFM also highlights zones of cold work or strain, for example, the work-hardening at a dent’s shoulders. This means MDS Pro can help rank dents, extending beyond just dent depth, considering signal responses in all six MDS Pro technologies – something geometry tools alone cannot do. In short, LFM acts as a ‘detector’ for metallurgical and stress anomalies, mapping locations where the steel itself is unusual. LFM can also indicate areas of heightened stress. This allows MDS Pro to be used to identify circumferential stress corrosion cracking (CSCC) and help prioritise uncharacteristic girth welds.
In mid-2024, T.D. Williamson (TDW) conducted an MDS Pro inspection on a gas pipeline that was over 50 years old. The LFM response prompted an excavation, and the hard spot – which standard MFL had not highlighted strongly – was confirmed and removed. In multiple other cases, LFM helps pinpoint critical dents, sometime very shallow, that have associated gouging; these dents are proactively repaired and the threat to pipeline integrity mitigated. These cases show LFM’s unique contribution: finding the unseen threats (material embrittlement, residual stress, or even material differences in the steel) that other ILI methods miss. For operators preparing pipelines for new challenges, LFM’s ability to identify hard spots and other material issues provides invaluable insight.
One-run synergy and value proposition
By integrating SMFL and LFM with conventional sensors on one platform, MDS Pro offers the most comprehensive picture in a single inspection. The synergy between datasets yields several benefits:
Full coverage of defect types: Axial MFL finds general corrosion; SMFL finds axial/seam anomalies; LFM finds hard spots and stress zones. Together, virtually all structural threats are detectable.
Better characterisation: Data fusion means an anomaly can be cross compared across multiple ILI technologies. For instance, a dent with metal loss will appear in geometry, MFL, SMFL, and LFM data – giving a multi-dimensional understanding of its severity.
Operational efficiency: One tool run replaces what previously might require three separate runs (geometry, high-field MFL, and a seam tool). This saves time and reduces costs and the risk of disruptions.
“Our Australian operators manage vast, remote pipelines and can’t afford multiple inspection runs,” TDW APAC Regional Manager of Pipeline Integrity Matt Runchey said. “MDS Pro’s ability to catch every threat in one go is a game-changer. We’re excited to bring this technology to solve pipeline challenges here, helping customers boost safety and efficiency.”
By combining multiple innovative technologies in a single survey run, MDS Pro detects and accurately identifies every critical anomaly, ensuring nothing is missed. For operators navigating aging infrastructure and rising integrity demands, MDS Pro delivers fewer surprises, greater certainty, and stronger operational confidence. One run is all it takes to uncover hidden threats, confirm pipeline integrity, and empower smarter, faster decisions.
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